WO2004077401A1 - Dip filter frequency characteristic decision method - Google Patents

Dip filter frequency characteristic decision method Download PDF

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Publication number
WO2004077401A1
WO2004077401A1 PCT/JP2004/002140 JP2004002140W WO2004077401A1 WO 2004077401 A1 WO2004077401 A1 WO 2004077401A1 JP 2004002140 W JP2004002140 W JP 2004002140W WO 2004077401 A1 WO2004077401 A1 WO 2004077401A1
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WO
WIPO (PCT)
Prior art keywords
frequency
dip
amplitude
frequency characteristic
curve
Prior art date
Application number
PCT/JP2004/002140
Other languages
French (fr)
Japanese (ja)
Inventor
Daisuke Higashihara
Original Assignee
Toa Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toa Corporation filed Critical Toa Corporation
Publication of WO2004077401A1 publication Critical patent/WO2004077401A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R29/00—Monitoring arrangements; Testing arrangements
    • H04R29/007—Monitoring arrangements; Testing arrangements for public address systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H13/00—Measuring resonant frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2227/00—Details of public address [PA] systems covered by H04R27/00 but not provided for in any of its subgroups
    • H04R2227/007—Electronic adaptation of audio signals to reverberation of the listening space for PA

Definitions

  • the invention according to the present application relates to a method for determining a frequency characteristic of a dip filter used for preventing resonance in a space where acoustic equipment is arranged.
  • the sound and loudspeakers from the loudspeakers are used due to the resonance frequency of this space (the loudspeaker space in which the sound equipment is arranged).
  • Voice may be difficult to hear. That is, if a loud sound from a speaker contains many components of the resonance frequency, resonance occurs at the frequency of this component in the loud sound space.
  • the resonance sounds like "Wong Won ⁇ ⁇ ⁇ " or "Fan fan ⁇ ⁇ ⁇ ". This resonance sound is not a sound that is supposed to radiate from the power, but makes it difficult to hear music and speech from speakers.
  • a dip filter that detects the resonance frequency in the loudspeaker space and removes the component of the resonance frequency in the sound equipment before the speaker may be provided. Then, resonance is less likely to occur in this loudspeaker space, and it is easier to hear music and speech from speed.
  • the frequency characteristics of the dip-filling must be determined so that the resonance frequency of this loudspeaker space is used as the removal frequency.
  • the present invention has been made in view of the above problems, and has as its object to provide a method for determining the frequency characteristics of a dip filter, which can appropriately determine the characteristics of the dip filter without requiring experience or skill.
  • a method of determining a frequency characteristic of a dip filter includes, among resonance frequencies detected in a resonance space, those below a predetermined frequency are excluded from the center frequency of the dip. Only a frequency exceeding a predetermined frequency is determined as a center frequency of the dip, a predetermined measurement signal is loudspeaked from a speaker arranged in the resonance space, and a measurement is obtained by receiving a sound by a microphone arranged in the resonance space.
  • a basic amplitude frequency characteristic is obtained based on the value, a target amplitude frequency characteristic having a greater smoothness on the frequency axis than the basic amplitude frequency characteristic is obtained based on the measured value, and the second area is approximately equal to the first area.
  • the attenuation level and sharpness of the dip are primarily determined so as to match, and the first area has a logarithmic axis representing an amplitude level as a vertical axis and an axis representing a frequency as a horizontal axis.
  • the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are represented on the amplitude frequency characteristic diagram, the basic amplitude frequency characteristic is obtained in the frequency range from the first frequency to the second frequency.
  • the first frequency is such that the curve of the basic amplitude frequency characteristic intersects with the curve of the target amplitude frequency characteristic;
  • Frequency lower than the center frequency of 0 of the wave numbers, the frequency closest to the center frequency of the dip, and the second frequency is such that the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect, and
  • the frequency closest to the center frequency of the dip among the frequencies higher than the center frequency, and the second area is an amplitude frequency having a logarithmic axis representing the amplitude level as a vertical axis and an axis representing the frequency as a horizontal axis. This is the area of the dip when the characteristics of the dip are represented on the characteristic diagram.
  • this method it is possible to objectively determine an appropriate characteristic to be set in the dip fill. Also, by setting the attenuation level and the sharpness of the dip determined primarily in this method to the dip fill, and using this dip fill in the sound system of the loudspeaker space, the amplitude frequency characteristic near the center frequency of the dip becomes The characteristic is very close to the target amplitude frequency characteristic. Therefore, resonance can be prevented without deteriorating sound quality. Also, of the resonance frequencies detected in the resonance space, those below a predetermined frequency are excluded from the center frequency of the dip, and only those exceeding the predetermined frequency are determined as the center frequency of the dip. The use of this dip-fill system in a system can prevent the volume of music and speech louder in the resonance space from becoming poor.
  • the predetermined frequency may be a frequency equal to or lower than 250 Hz.
  • frequencies below 250 Hz Let fa (H z) be the reference frequency, and those of the resonance frequencies detected in the resonance space that are lower than fa (H z) are calculated from the center frequency of the device. It may be excluded and only those exceeding fa (Hz) may be determined as the center frequency of the dip.
  • a method for determining a frequency characteristic of a dip filter determines a resonance frequency detected in a resonance space as a center frequency of the dip, and uses a speaker arranged in the resonance space to determine a resonance frequency.
  • a predetermined measurement signal is loudspeaked, and a fundamental amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space.
  • the target amplitude frequency characteristic with a large smoothness on the wavenumber axis is found, and the second area is The attenuation level and the sharpness of the dip are primarily determined so as to substantially match, and when the primarily determined attenuation level is less than a predetermined level, the attenuation level is secondarily determined to further increase the level.
  • the first area is obtained by dividing the basic amplitude frequency characteristic curve and the target amplitude frequency characteristic curve on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the vertical axis and the frequency axis as the horizontal axis.
  • the first frequency In the frequency range from the first frequency to the second frequency when expressed, it is the area of the area surrounded by the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic, and the first frequency is The curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect, and the frequency closest to the center frequency of the dip among the frequencies lower than the center frequency of the dip.
  • the second frequency is such that the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect, and which is closest to the center frequency of the dip among the frequencies higher than the center frequency of the dip
  • the second area is the frequency of the dip when the characteristic of the dip is represented on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the vertical axis and the axis representing the frequency as the horizontal axis. Area.
  • this method it is possible to objectively determine an appropriate characteristic to be set in the dip fill. Also, if the attenuation level and the sharpness of the dip determined first in this method are set to dip fill, and this dip filter is used in the sound system of the loudspeaker space, the amplitude frequency characteristic near the center frequency of the dip becomes the target The characteristic is very close to the amplitude frequency characteristic. Therefore, resonance can be prevented without deteriorating sound quality.
  • the primary determined attenuation level is equal to or lower than the predetermined level, the secondary determination determines the attenuation level so as to be higher. Therefore, when this dip filter is used for the acoustic system in the resonance space, it is possible to hear the sound if the resonance is prevented in the resonance space.
  • the secondary determination may include determining the attenuation level to be the predetermined level. For example, when the attenuation level determined by the primary determination is less than L h (dB), the attenuation level may be determined to be L h (dB) by the secondary determination.
  • a ditto having a frequency equal to or lower than a predetermined frequency as a center frequency Only at the second stage, a secondary decision may be made on the attenuation level.
  • the attenuation level of the dip for removing a component having a frequency higher than the predetermined frequency is not increased by the secondary determination. Since components at frequencies higher than a certain frequency have a large contribution to speech intelligibility, setting the dip characteristics determined by such a method to dip-filling will not reduce speech intelligibility.
  • a method for determining a frequency characteristic of a dip filter determines a resonance frequency detected in a resonance space as a center frequency of the dip, and a speaker arranged in the resonance space.
  • a predetermined measurement signal is loudspeaked, and a basic amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space.
  • a target amplitude frequency characteristic having a large degree of smoothness on the frequency axis is obtained, and an attenuation level and a sharpness of the dip are primarily determined so that the second area substantially matches the first area, and the primary determined sharpness is determined.
  • the sharpness is secondarily determined so as to further reduce the value
  • the first area is an axis representing a logarithmic axis representing the amplitude level and an axis representing the frequency.
  • the frequency that intersects and is higher than the center frequency of the dip is the frequency closest to the center frequency of the dip, and the second area has a logarithmic axis representing an amplitude level as a vertical axis and a frequency When representing the characteristics of the dip on the amplitude-frequency characteristic diagram of the shaft and the horizontal axis representing the is the area of the dip.
  • the attenuation level and the sharpness of the dip determined in this way are set in the dip filter, and applied to the sound system of the loudspeaker space.
  • the amplitude frequency characteristic near the center frequency of the dip is very close to the target amplitude frequency characteristic. Therefore, resonance can be prevented without deteriorating sound quality. If the sharpness is too high, you may feel uncomfortable when you set the characteristics of the dip filter. This is because the greater the sharpness, the greater the change in phase near the center frequency of the dip in the frequency characteristics of the dip fill. In other words, a sudden change in the phase on the frequency axis gives a sense of incongruity in hearing.
  • the secondary determination determines the sharpness so that the value is further reduced. Therefore, if this dip filter is used for the acoustic system in the resonance space, the sound quality in the resonance space will not be significantly impaired, and the listener will not feel uncomfortable.
  • the secondary determination may be made such that the sharpness is set to the predetermined value.
  • the target amplitude frequency characteristic may be smoothed by any method.
  • the target amplitude frequency characteristic is smoothed by moving and averaging the measured amplitude frequency characteristic on the frequency axis. May be.
  • an attenuation level of the dip is determined so as to substantially match an amplitude level difference between the basic amplitude frequency characteristic and the target amplitude frequency characteristic at a center frequency of the dip;
  • the sharpness may be determined such that the first area is substantially equal to the second area.
  • the dip characteristic determined by such a method When the dip characteristic determined by such a method is applied to the basic amplitude frequency characteristic, the characteristic becomes very close to the target amplitude frequency characteristic.
  • a second amplitude frequency of the plurality of resonance frequencies is determined as the center frequency of the dip, and the other resonance frequencies are determined so as not to be the center frequency of the dip.
  • An amplitude frequency characteristic obtained by loudspeaking a composite signal of the measurement signal and the output signal of the microphone from the speaker and receiving the sound by the microphone may be used.
  • the resonance frequency of the resonance space is detected based on a comparison between the first amplitude frequency characteristic and the second amplitude frequency characteristic, and the first amplitude frequency characteristic is determined based on the measured value.
  • the second amplitude frequency characteristic is obtained by loudspeaking a composite signal of the measurement signal and the output signal of the microphone from the speaker and receiving the sound by the microphone.
  • the amplitude frequency characteristic may be used.
  • the second amplitude frequency characteristic in such a method is an amplitude frequency characteristic of a system including a feedback loop in which the output signal of the microphone is input to the speaker. With this feedback loop, the resonance characteristics of the resonance space appear more emphasized in the second amplitude frequency characteristics than in the first amplitude frequency characteristics. Therefore, by comparing the first amplitude frequency characteristic and the second amplitude frequency characteristic, the resonance frequency of the resonance space can be accurately detected.
  • a peak having a larger amplitude in the second amplitude frequency characteristic than in the first amplitude frequency characteristic is obtained from a difference between the first amplitude frequency characteristic and the second amplitude frequency characteristic.
  • the frequency of the point may be detected as the resonance frequency of the resonance space.
  • a sine wave sweep signal is particularly effective as the measurement signal.
  • FIG. 1 is a schematic configuration diagram of an acoustic system installed in a loudspeaker space.
  • FIG. 2 is a schematic block diagram of a system for measuring amplitude frequency characteristics in a loudspeaker space.
  • FIG. 3 is a schematic block diagram of a system for measuring amplitude frequency characteristics in a loudspeaker space. .
  • Fig. 4 schematically shows the first amplitude frequency characteristic of the loudspeaker space measured by the system of Fig. 2 and the second amplitude frequency characteristic of the loudspeaker space measured by the system of Fig. 3 It is a characteristic diagram.
  • FIG. 5 is a frequency characteristic diagram showing an amplitude level difference between a first amplitude frequency characteristic of a curve C a in FIG. 4 and a second amplitude frequency characteristic of a curve C b.
  • FIG. 6 is a frequency characteristic diagram obtained by extracting only the curve Cb from the frequency characteristic diagram of FIG.
  • FIG. 7 is a frequency characteristic diagram showing a curve C a of the basic amplitude frequency characteristic and a curve C d of the target amplitude frequency characteristic.
  • FIG. 8 is a frequency characteristic diagram showing a case where three candidate frequencies exist in a frequency range from a frequency f61 to a frequency f62.
  • FIG. 9 is an amplitude frequency characteristic diagram of a dip whose center frequency is frequency f2.
  • FIG. 1 is a schematic configuration diagram of a sound system installed in a public space (for example, a concert hall or a gymnasium) 40.
  • This acoustic system includes a sound source device 2, a dip filter 4, an amplifier 12, and a speaker 13.
  • the sound source device 2 may be, for example, a playing device such as a CD player for reproducing music CD, or a microphone and a microphone.
  • the sound source device 2 is shown outside the sound space 40 in FIG. 1, the sound source device 2 may be installed in the sound space 40.
  • the sound source device 2 may be a microphone installed in the loudspeaker space 40.
  • the dip filter 4 is for removing a signal component of a specific frequency from the signal from the sound source device 2 and transmitting the signal component to the amplifier 12.
  • the signal from the dip filter 4 is amplified by the amplifier 12 and transmitted to the speaker 13, and is amplified from the speaker 13 in the sound space 40.
  • the frequency characteristic to be set in the dip filter 4 is determined. First, a method and an apparatus for detecting a resonance frequency in the resonance space 40 will be described with reference to FIGS. I do.
  • FIG. 2 is a schematic block diagram of a system A for measuring amplitude frequency characteristics in a public space (for example, a concert hall or a gymnasium) 40.
  • the system A includes a transmitter 11 as a sound source for generating a signal for measurement, an amplifier 12 for inputting a signal generated by the transmitter 11 and amplifying power, and a loudspeaker receiving an output signal of the amplifier 12 and inputting a signal.
  • the microphone 14 may be a sound level meter.
  • the speaker 13 and the microphone 14 are arranged in a sound space 40.
  • the microphone 14 is sufficiently far from the speaker 13 in the sound space 40.
  • the microphone 14 is arranged at a position where the reflected sound in the loudspeaker space 40 can be received at a sufficiently large level with respect to the direct sound from the speaker 13.
  • the transmitter 11 emits a sine wave signal whose frequency changes with time as a measurement signal. That is, the transmitter 11 transmits a sine wave sweep signal. In the sine wave sweep signal, the level of the sine wave is constant at each point in the frequency sweep.
  • the measuring device 15 has a bandpass filter whose center frequency changes with time. This band-pass filter temporally changes the center frequency in response to the temporal change of the frequency of the sine wave sweep signal transmitted by the transmitter 11. Therefore, measuring instrument 15 can measure the amplitude characteristic of the frequency at that time by detecting the level of the sound reception signal input from microphone 14 through this bandpass filter.
  • FIG. 3 is a schematic block diagram of a system B for measuring the amplitude frequency characteristic in the loudspeaker space 40.
  • This system B is obtained by adding a path for synthesizing a certain signal to the system A shown in FIG.
  • the system B shown in FIG. 3 is composed of a transmitter 11 serving as a sound source for emitting a signal for measurement, a mixing device 16, ⁇ An amplifier 12 which receives the output signal of the device 16 and amplifies the power of the signal, a speaker 13 which receives the output signal of the amplifier 12 and loudspeaks, and a microphone 14 which receives the loudspeaker radiated by the speaker 13. And a measuring device 15 for inputting a sound reception signal of the microphone 14.
  • the speaker 13 and the microphone 14 are arranged at the same position in the loudspeaker space 40 as in the system A in FIG.
  • the transmitter 11, the amplifier 12, the speed 13, the microphone 14, and the measuring instrument 15 in the system B in FIG. 3 are the same as those in the system A in FIG.
  • the difference between the system B in Fig. 3 and the system A in Fig. 2 is that in the system A in Fig. 2, the amplifier 12 inputs the signal from the transmitter 11, whereas the system B in Fig. 3 In B, the amplifier 12 receives a signal from the mixing device 16.
  • the mixing device 16 shown in FIG. 3 inputs the measurement signal (sine-wave sweep signal) from the transmitter 11 and the sound reception signal from the microphone 14, and synthesizes (mixes) these input signals. Outputs the composite signal (mixing signal).
  • the method of measuring the amplitude frequency characteristics of the loudspeaker space 40 by the system A in FIG. 2 and the method of measuring the amplitude frequency characteristics of the loudspeaker space 40 by the system B in FIG. 3 have been described above.
  • the amplitude frequency characteristic of the loudspeaker space 40 measured by the system A in FIG. 2 is called a first amplitude frequency characteristic
  • the amplitude frequency characteristic of the loudspeaker space 40 measured by the system B in FIG. It is called the amplitude frequency characteristic of 2.
  • FIG. 4 shows the first amplitude frequency characteristics of the loudspeaker space 40 measured by the system A in FIG. 2
  • FIG. 3 is a characteristic diagram schematically showing In FIG.
  • both the vertical and horizontal axes are logarithmic axes, the vertical axis represents the amplitude level, and the horizontal axis represents the frequency.
  • the “amplitude level” is the logarithm of the ratio of a certain amplitude value (magnitude of amplitude) to a reference value (magnitude of reference), and is usually expressed in units of “dB”.
  • the curve C a shown by a solid line in FIG. 4 is the first amplitude frequency characteristic by the system A in FIG. 2, and the curve C b shown by a broken line is the second amplitude frequency characteristic by the system B in FIG. is there.
  • Both system A in Fig. 2 and system B in Fig. 3 measure amplitude values at a number of frequency points.
  • Db octave ⁇ Measure the amplitude value at intervals (D b is a positive number sufficiently smaller than 1).
  • the measured values at these multiple points may be represented on the curves C a and C b as the first and second amplitude frequency characteristics of the loudspeaker space 40 without being smoothed on the frequency axis.
  • it may be smoothed on the frequency axis by some method and may be represented by curves C a and C b.
  • smoothing may be performed by a moving average.
  • a moving average of Nc points may be applied to a large number of measured values of frequency points on the frequency axis (Nc is a predetermined natural number).
  • Nc is a predetermined natural number.
  • a smoothed curve C a it is preferable to use a smoothed curve C b as well.
  • the curve Cb it is preferable to obtain the curve Cb by the same smoothing method as that for the curve Ca.
  • the curve C b is also preferably obtained by a moving average of N c points on the frequency axis.
  • the first amplitude frequency characteristic of the curve Ca in FIG. 4 includes not only the characteristic of the acoustic system including the amplifier 12, the speaker 13, and the microphone 14, but also the characteristic of the resonance of the loudspeaker space 40.
  • the second amplitude frequency characteristic of the curve Cb in FIG. 4 also includes not only the characteristic of the acoustic system by the amplifier 12, the speaker 13, and the microphone 14, but also the characteristic of the resonance of the loudspeaker space 40.
  • the resonance characteristic of the loudspeaker space 40 is lower than the first amplitude frequency characteristic of the curve Ca. It is greatly emphasized. Therefore, the resonance characteristics of the loudspeaker space 40 can be known from the difference between the two curves (the curves C a and C b).
  • the frequency characteristic curve C c shown in FIG. 5 is a characteristic obtained by subtracting the characteristic of the curve C a from the characteristic of the curve C b of FIG. 4, that is, the first amplitude frequency characteristic of the curve C a and the characteristic of the curve C b It shows the amplitude level difference from the amplitude frequency characteristic of No. 2.
  • the frequencies that show peaks in the positive direction in the curve Cc in FIG. 5 are the frequency f1, the frequency f2, and the frequency f3. It is highly probable that these frequencies are the resonance frequencies of the loudspeaker space 40.
  • the number of resonance frequencies in the loudspeaker space 40 is not limited to one, but is often plural. Therefore, only one of the frequencies fl, ⁇ 2, and f3 may be the resonance frequency, and more than one of them may be the resonance frequency. ⁇ ⁇ It is possible to objectively select the potential resonance frequency.
  • the curve Ca in FIG. 4 is a first amplitude frequency characteristic curve of the loudspeaker space 40 obtained by the system A in FIG. 2, and the resonance frequency is detected using the curve Ca as described above.
  • the characteristic of this curve C a is also used for determining the frequency characteristic of the dip filter 4 of the acoustic system of FIG. 1 described below.
  • the characteristic of the curve C a is referred to as “basic amplitude frequency characteristic”. Note that this “basic amplitude frequency characteristic” may be a value obtained by smoothing the measured values at a number of frequency points by the system A in FIG. 2 on the frequency axis or not. May be.
  • the frequency f1, the frequency ⁇ 2, and the frequency f3 were obtained from the frequency characteristic curve shown in FIG. 5 as the frequencies showing the peaks in the positive direction. It is highly possible that these frequencies are the resonance frequencies of the loudspeaker space 40.
  • any of these frequencies (frequency 1, frequency f2, frequency 3) is less than fd (Hz)
  • that frequency (frequencies less than fd (Hz)) will be Exclude from the candidates for the center frequency of the dip to be set as the rejection frequency
  • the frequency below fd (H z) is excluded from the candidates for the following reason. That is, frequency components below a certain frequency in music or speech have a large effect on the volume. If a frequency lower than a certain frequency is set as the center frequency of the dip in the dip fill 4, the volume of the music and voice loudspeaked in the loudspeaker space 40 becomes poor.
  • candidate frequencies are selected from these frequencies in order from the one with the largest amplitude level of the curve Cb in FIG.
  • FIG. 6 is a characteristic diagram obtained by extracting only the curve Cb from FIG.
  • both the vertical and horizontal axes are logarithmic axes, with the vertical axis representing amplitude level and the horizontal axis representing frequency.
  • the amplitude level at the frequency f2 is the highest
  • the amplitude level at the frequency f3 is the next highest
  • the amplitude level at the frequency f1 is the next highest.
  • the number of frequencies to be selected as candidates is “3”
  • all of the frequencies f 1, f 2 and f 3 are candidate frequencies.
  • the candidate frequencies (frequency 1, f2, f3) are ranked.
  • the order of the frequency characteristic curve Cc in FIG. Of the frequencies f 1, ⁇ 2, and f 3, the frequency f 3 has the largest amplitude level in the curve C c in FIG. 5, and the frequency level f 2 has the next largest amplitude level.
  • the next largest amplitude level is the frequency f1. Therefore, at this point, the frequency f3 is the frequency of the first candidate, the frequency f2 is the frequency of the second candidate, and the frequency f1 is the frequency of the third candidate.
  • the target amplitude frequency characteristic is obtained from the measured values measured at a number of frequency points by the system A in FIG.
  • the target amplitude frequency characteristic is obtained by smoothing the measured values measured by the system A in FIG. 2 at a number of frequency points on the frequency axis.
  • the smoothing method for example, a moving average on the frequency axis can be adopted.
  • the curve C a (basic amplitude frequency characteristic) in FIG. 4 shows that the system A in FIG. He stated that the measured value measured at the point may be smoothed on the frequency axis, or may not be smoothed.
  • the basic amplitude frequency characteristic may or may not be smoothed, but the target amplitude frequency characteristic is obtained by smoothing.
  • the target amplitude frequency characteristic is obtained by smoothing such that the smoothness on the frequency axis is larger than the basic amplitude frequency characteristic.
  • Fundamental amplitude frequency characteristic Force If it is obtained by, for example, moving average of Nc points on the frequency axis (Nc is a predetermined natural number), the target amplitude frequency characteristic is a window width exceeding Nc point ( For example, it may be obtained by a moving average of N f points (N f is a natural number exceeding N c). In this way, the target amplitude frequency characteristic can be obtained objectively without relying on experience.
  • the curve Ca is extracted from FIG. 4 and described.
  • both the vertical and horizontal axes are logarithmic axes, with the vertical axis representing amplitude level and the horizontal axis representing frequency.
  • the curve C a in FIG. 7 is the same as the curve C a in FIG.
  • the characteristic diagram in Fig. 7 shows a dashed curve C d (curve C d), which represents the amplitude values at a number of frequency points measured by system A in Fig. 2, It is a curve obtained by moving average on the axis. Since the window width for the moving average at this time is relatively large, the smoothness of the curve C d (target amplitude frequency characteristic) is considerably larger than that of the curve C a (basic amplitude frequency characteristic).
  • frequency f3 was selected as the first candidate frequency
  • frequency f2 was selected as the second candidate frequency
  • frequency f1 was selected as the third candidate frequency.
  • the target amplitude was selected.
  • Frequencies in which the amplitude level of the fundamental amplitude frequency characteristic (curve C a) is smaller than the amplitude level of the frequency characteristic (curve C d) are excluded from candidates.
  • the amplitude level of the basic amplitude frequency characteristic (curve C a) is smaller than the amplitude level of the target amplitude frequency characteristic (curve C d). Therefore, the frequency f1 is excluded from the candidate frequencies.
  • the candidate frequencies are only the frequency f2 and the frequency f3.
  • the frequency f3 remains as the first candidate frequency
  • the frequency f2 remains as the second candidate frequency.
  • a curve C a of the basic amplitude frequency characteristic from the curve C d of the target amplitude frequency characteristic is a frequency range in which the frequency of each candidate is included on the frequency axis. 1 c
  • the frequency of the first candidate is frequency f3, in FIG. 7, at frequency f3, the amplitude level of the basic amplitude frequency characteristic is higher than the target amplitude frequency characteristic.
  • the frequency ⁇ 31 and the frequency f 32 is detected.
  • the curve C a of the fundamental amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic intersect.
  • the frequency f31 is the frequency closest to the frequency f3 among the intersections of the curve C a of the fundamental amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic in a frequency region lower than the frequency f 3.
  • the frequency f32 is the frequency closest to the frequency f3 at the intersection between the curve C a of the basic amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic in a frequency region higher than the frequency f3. is there.
  • the candidate frequency f 3 is included, and the curve C a of the fundamental amplitude frequency characteristic is continuously shifted from the curve C d of the target amplitude frequency characteristic in the positive direction (upward) on the frequency axis.
  • the protruding frequency range the range from frequency f31 to frequency 32
  • the candidate frequency f2 the frequency range in which the frequency f2 is included, the frequency where the fundamental amplitude frequency characteristic (curve C a) from the target amplitude frequency characteristic (curve C d) continuously protrudes in the positive direction on the frequency axis.
  • a number range is first detected. As shown in Fig. 7, in the frequency range from frequency f21 to frequency f22, the fundamental amplitude frequency characteristic (curve C a) from the target amplitude frequency characteristic (curve C d) continuously appears on the frequency axis. It protrudes in the positive direction. Also, this The frequency range includes the frequency f2. Next, looking at whether this frequency range contains two or more candidate frequencies, there are no candidate frequencies other than frequency ⁇ 2 in this frequency range. Therefore, no frequencies are excluded from the candidate in this frequency range.
  • a curve Ce in the characteristic diagram of FIG. 8 is a curve showing the basic amplitude frequency characteristic
  • a curve C ⁇ is a curve showing the target amplitude frequency characteristic. Both curves intersect at frequency f61 and frequency f62, and three frequencies (frequency f51, frequency f52 and frequency f52) that fall into this frequency range (frequency range from frequency ⁇ 61 to frequency f62) Suppose that a frequency f53) exists.
  • the curve C n represents the second amplitude frequency characteristic, that is, the resonance signal 40 loudspeaks the composite signal of the measurement signal (sine wave sweep signal) and the output signal of the microphone 14 from the speaker 13. And amplitude frequency characteristics obtained by receiving sound with the microphone U.
  • the amplitude level of the second amplitude frequency characteristic (curve Cn) is the largest at the frequency f51. Therefore, only the frequency f51 is left as a candidate frequency, and the other frequencies (frequency f52 and frequency f53) are excluded from the candidates. This prevents more than necessary frequencies from remaining as candidate frequencies. As a result, it is possible to prevent more dips from being set in the dip fill 4 than necessary.
  • the candidate frequency (frequency f51, frequency f52, frequency f53) has a difference in amplitude level between the fundamental amplitude frequency characteristic (curve C e) and the second amplitude frequency characteristic (curve C n) below a predetermined level ( For example, if there is one that is less than I dB, the frequency should not be set as the center frequency of the dip in dip filter 4.
  • the frequency f 51 is excluded from the candidate frequencies, and the frequency f 52 having the second highest amplitude level of the amplitude frequency characteristic (curve C n) is selected as the candidate.
  • a predetermined level for example, less than ld B
  • the frequency f 51 is excluded from the candidate frequencies, and the frequency f 52 having the second highest amplitude level of the amplitude frequency characteristic (curve C n) is selected as the candidate.
  • Frequency is the candidate frequency Excluded from
  • Fig. 7 it is the frequency range that includes the candidate frequency, and the basic amplitude frequency characteristic (curve Ca) continuously protrudes in the positive direction from the target amplitude frequency characteristic (curve Cd) on the frequency axis.
  • Frequency range is detected first. Then, in each of the detected frequency ranges, no more than two candidate frequencies are included, so that the candidate frequencies f 2 and f 3 remain as candidates without being excluded. explained.
  • the remaining frequency candidates are rearranged in the candidate order.
  • the replacement is performed as follows. In other words, the order is changed so that the higher the amplitude level difference between the basic amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) at the candidate frequency, the higher the rank.
  • the amplitude level difference between the fundamental amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) at frequency ⁇ 2 is 2.5 dB
  • the fundamental amplitude frequency characteristic at frequency ⁇ 3 is
  • the amplitude level difference between the amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) is 1.8 dB. Therefore, the order of the candidates is changed, and the frequency f2 becomes the first candidate, and the frequency f3 becomes the second candidate.
  • the frequency f2 which is the first candidate, is set in the dip filter 4 as the center frequency (removal frequency) of the dip.
  • the procedure for determining the dip attenuation level (depth) and the sharpness (Q) at the removal frequency (frequency f 2) will be described.
  • the magnitude of the amplitude level difference between the target amplitude frequency characteristic (curve Cd) and the fundamental amplitude frequency characteristic (curve Ca) at the frequency f2 is detected, and this magnitude (the magnitude of the difference) is dip-filled.
  • the difference in amplitude level between the target amplitude frequency characteristic (curve Cd) and the basic amplitude frequency characteristic (curve Ca) is 2.5 dB, so the dip depth is assumed to be 2.5 dB first.
  • the sharpness (Q) of the dip is first assumed to be 40.
  • the dip area is determined from the dip shape (dip shape on the amplitude frequency characteristic diagram) obtained from the assumed dip depth and sharpness.
  • the amplitude frequency characteristic of the dip whose center frequency is the frequency f2 is represented by a curve Cg.
  • both the vertical and horizontal axes are logarithmic axes, and the vertical axis shows the amplitude level and the horizontal axis shows the frequency.
  • the area of the area S2 with many parallel diagonal lines is the dip area here.
  • the area of the dip obtained from the assumed dip depth and sharpness is defined as T2.
  • the area T1 and the area T2 are compared. If the area T2 is equal to or greater than the area T1, the attenuation level and the sharpness assumed at that time are primarily determined as the dip attenuation level and the sharpness at the dip filter 4 removal frequency. You.
  • the sharpness is reduced by 0.1 and the area T2 is calculated again. Then, the area T1 and the area T2 are compared again. If the area T2 is equal to or larger than the area T1, the attenuation level and the sharpness assumed at that time are primarily determined as the dip attenuation level and the sharpness at the rejection frequency of the dip filter 4. If the area T 2 is smaller than the area T 1, the sharpness is further reduced by 0.1 to determine the area T 2 again, and the area T 1 and the area T 2 are compared again. Similarly, the sharpness is reduced by 0.1 until the area T2 is equal to or greater than the area T1, and the attenuation level when the area T2 is equal to or greater than the area T1. And the sharpness are primarily determined as the dip attenuation level and the sharpness at the removal frequency of the dip filter 4.
  • the area T2 remains smaller than the area T1 even if the sharpness is reduced to a predetermined value (for example, 1.5), then the sharpness is not reduced and the attenuation level is reduced to the predetermined value (for example, 1.5). For example, 0.5 dB). Then, when the area T2 becomes equal to or larger than the area T1, the attenuation level and the sharpness are removed by dip fill 4 It is primarily determined as the dip attenuation level and sharpness at the frequency.
  • the attenuation level and the sharpness at that time are reduced by the rejection frequency of the dip filter 4. Is determined primarily as the dip attenuation level and sharpness at.
  • the first rejection frequency (center frequency of the dip) to be set in the dip filter 4 and the attenuation level and sharpness of the dip at that frequency can be primarily determined.
  • the secondary determination of the dip attenuation level and the sharpness is necessary.
  • the judgment of this secondary decision is made as follows. The specific method of the secondary determination depends on the center frequency of the dip.
  • the quadratic determination of the dip attenuation level is performed only when the center frequency of the dip is less than f g (H z). If the center frequency of the dip is less than fg (H z) and the attenuation level determined by the primary determination of the dip is less than L h (d B), the attenuation level of the dip is set to L h (d B) Make a secondary decision to make Then, the attenuation level determined by this secondary determination finally becomes the attenuation level of the dip to be set in the dip filter 4.
  • the center frequency of the dip is equal to or lower than fg (Hz)
  • the attenuation level determined by the primary determination of the dip is equal to or higher than Lh (dB)
  • the attenuation level determined by the primary determination is two times. The next decision is not made, and the attenuation level determined by the primary decision finally becomes the dip attenuation level to be set in the dip filter 4.
  • the attenuation level determined by the primary determination is The next decision is not made, and the attenuation level determined by the primary decision is the dip attenuation level to be finally set in dip field 4.
  • the quadratic determination of dip sharpness (Q) depends on the center frequency of the dip different.
  • the sharpness of the dip make a secondary decision to change the degree to j. Then, the sharpness determined by this secondary determination finally becomes the sharpness of the dip to be set in the dip fill 4. Even if the center frequency of the dip is less than fi (Hz), if the sharpness determined by the primary determination of the dip is J or less, no secondary determination is made for the primary determined sharpness, The sharpness determined by the primary determination finally becomes the sharpness of the dip to be set in the dip filter 4.
  • the sharpness determined by the primary determination of the dip is less than K, the secondary determination will not be performed on the primary determined sharpness.
  • the sharpness determined by the primary determination is the sharpness of the dip to be finally set in the dip filter 4.
  • the quadratic is changed to change the sharpness of the dip to L Make a decision. Then, the sharpness determined by the secondary determination finally becomes the sharpness of the dip to be set in the dip filter 4.
  • the frequency 2 is a frequency not less than fi (Hz) and not more than fg (Hz). Then, it is assumed that the attenuation level determined by the primary determination of the dip with the frequency f2 as the center frequency is less than Lh (dB). Then, the dip attenuation level is secondarily determined to Lh (d B). The dip attenuation level finally determined in this way ⁇ Is the dip characteristic to be set in the dip filter 4.
  • the secondary determination of the sharpness for the frequency f2 is determined. If the sharpness determined primarily at this frequency ⁇ 2 exceeds ⁇ , a secondary decision is made to change the sharpness of the dip to ⁇ . If the sharpness determined by the primary determination is less than or equal to ⁇ , no secondary determination is made for the primary determined sharpness.
  • the secondary determination of the attenuation level has the meaning of fine adjustment in order to make the effect of the dip filter 4 effective on hearing.
  • the dip for performing the secondary determination of the attenuation level is limited to those having a frequency equal to or lower than ⁇ g (Hz) because the sound radiated from the speaker 13 in the loudspeaker space 40 (see FIG. 1) This is to prevent the degree from decreasing.
  • the frequency component higher than the predetermined frequency for example, higher than fg (Hz) in this embodiment greatly contributes to the intelligibility of the voice. This is because clarity may be reduced.
  • the sharpness of the first-determined dip is too large, that is, if the width of the dip is too narrow, setting this sharpness as it is in the dip filter 4 will greatly impair the sound quality and make the listener feel uncomfortable. There is. In order to avoid such a situation, in the secondary decision, the sharpness was further reduced in order to increase the dip width. This avoids a sudden change in the phase near the center frequency of the dip in the frequency characteristics of the dip filter 4, and does not significantly impair the sound quality in the resonance space, and gives a sense of discomfort to the listener. Will not be. In other words, the secondary determination of the sharpness has the meaning of fine adjustment of the characteristics of the dip filter 4.
  • the frequency f3 which is the second candidate frequency, is determined as the second removal frequency (center frequency of the dip) to be set in the dip filter 4, and the attenuation level and the sharpness of the dip at that frequency are determined. Is first determined.
  • the frequency f 3 is higher than f g (H z). Then, even if the attenuation level determined by the primary determination of the dip is lower than L h (dB) or higher than L h (dB), the attenuation level determined by the primary determination is On the other hand, the secondary decision is not made, and the attenuation level by the primary decision finally becomes the dip attenuation level to be set in the dip filter 4.
  • the secondary determination of the sharpness for the frequency f3 is determined. Since the frequency f 3 is higher than fg (H z), if the sharpness determined at this frequency f 3 exceeds L, the secondary is changed so that the sharpness of the dip is changed to L. Make a decision. If the sharpness determined by the primary determination is less than L, no secondary determination is made for the primary determined sharpness.
  • the frequency f1 Since the frequency f1 has already been excluded from the candidate frequencies, in the present embodiment, only the frequency f2 and the frequency f3 are the removal frequencies (the center frequencies of the dips) to be set in the dipfiller 4.
  • the frequencies f 2 and f 3 to be set as the removal frequencies in the dip filter 4 and the attenuation level (depth) and sharpness (Q) of the dip at that frequency are determined. Then, these characteristics are compared with the dip
  • the characteristics of the filter 4 as c above the resonance can be prevented in the loud sound space 40, and dip attenuation level set in the dip filter 4 and acuity, primary determined attenuation level and quality factor If it remains as it is, the area of the dip is approximately equal to the area where the fundamental amplitude frequency characteristic protrudes from the target amplitude frequency characteristic, and in principle, the fundamental amplitude frequency at the resonance frequency (center frequency of the dip)
  • the amplitude level difference between the characteristic and the target amplitude frequency characteristic is set as the dip attenuation level of the dip filter 4.
  • the characteristics of the dip filter 4 when the characteristics of the dip filter 4 are applied to the basic amplitude frequency characteristics, the characteristics become very close to the target amplitude frequency characteristics, and the sound system of FIG. 1 including the dip filter 4 set to such characteristics impairs sound quality. It is set to an appropriate characteristic that can prevent resonance.
  • the attenuation level of the dip set in the dip filter 4 is a secondary-determined attenuation level, if resonance is prevented in the resonance space 40, the user can feel it audibly. Further, if the sharpness of the dip set in the dip fill 4 is the secondarily determined sharpness, sound quality that does not cause a sense of discomfort in the resonance space 40 can be obtained.
  • the secondary determination of the dip attenuation level is performed only on the frequency equal to or lower than the predetermined frequency (fg (Hz)).
  • a restriction frequency restriction
  • the secondary decision may be made to further increase the attenuation level if the attenuation level of the dip is equal to or lower than a predetermined level.
  • a frequency less than fi (Hz) is based on the sharpness of J, and a frequency less than fi (Hz) and fg (Hz) is less than fi (Hz).
  • the sharpness of K was used as a reference.
  • different values of sharpness are provided as a reference depending on the frequency.
  • a fixed value of the sharpness may be used as a reference regardless of the frequency.
  • the case where the number of candidate frequencies to be set for the dip-fill 4 is relatively small is shown.
  • the dip-fill 4 The same procedure can be used to determine as many rejection frequencies as possible (for example, 12 rejection frequencies), and the attenuation level and sharpness at those frequencies.
  • the remaining candidate frequencies are not set as the removal frequencies in the dip filter 4.
  • the characteristic of the dip filter can be appropriately determined without the need for experience or skill, which is useful in the technical field of audio equipment.

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Abstract

Resonance frequencies f2, f3 detected in a resonance space are decided to be dip center frequencies. According to the measurement values obtained in a loudspeaker and a microphone in the resonance space, a basic amplitude frequency characteristic Ca and a target amplitude frequency characteristic Cd are obtained. The target amplitude frequency characteristic Cd has a greater smoothness than the basic amplitude frequency characteristic Ca on the frequency axis. The dip attenuation level and sharpness are decided according to the difference between the basic amplitude frequency characteristic Ca and the target amplitude frequency characteristic Cd at the dip center frequencies f2, f3 and in the vicinity thereof. However, no frequency below a predetermined frequency is made a dip center frequency.

Description

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明 細 書 ディップフィル夕の周波数特性決定方法 Description How to determine the frequency characteristics of dip fill
[技術分野] [Technical field]
この出願に係る発明は、 音響設備が配置された空間において共鳴を防止するた めに用いられるディップフィル夕の周波数特性を決定する方法に関する。  The invention according to the present application relates to a method for determining a frequency characteristic of a dip filter used for preventing resonance in a space where acoustic equipment is arranged.
[背景技術] [Background technology]
例えば、 ホールや体育館等にスピーカ等の音響設備を設置し、 スピーカから拡 声音を放射するとき、 この空間 （音響設備が配された拡声空間） の共鳴周波数の ために、 スピーカからの音楽や話声が聞き取りにくくなることがある。 つまり、 スピーカからの拡声音に共鳴周波数の成分が多く含まれると、 該拡声空間におい てこの成分の周波数で共鳴が起こるのである。 共鳴音は 「ウォンウォン · · ·」 とか 「ファンファン · · ·」 というように聞こえる。 この共鳴音は、 本来、 スピ —力から放射しょうとする音ではなく、 スピーカからの音楽や話声を聞き取りに くくする。  For example, when sound equipment such as speakers is installed in a hall or gymnasium, and loudspeakers are radiated from the loudspeakers, the sound and loudspeakers from the loudspeakers are used due to the resonance frequency of this space (the loudspeaker space in which the sound equipment is arranged). Voice may be difficult to hear. That is, if a loud sound from a speaker contains many components of the resonance frequency, resonance occurs at the frequency of this component in the loud sound space. The resonance sounds like "Wong Won · · ·" or "Fan fan · · ·". This resonance sound is not a sound that is supposed to radiate from the power, but makes it difficult to hear music and speech from speakers.
このことを防止するには、 拡声空間における共鳴周波数を検出し、 音響設備に おいてスピーカよりも前段に、 この共鳴周波数の成分を除去するようなディップ フィルタを設けるとよい。 するとこの拡声空間において共鳴が起こりにくくなり、 スピー力からの音楽や話声が聞きやすくなる。  To prevent this, a dip filter that detects the resonance frequency in the loudspeaker space and removes the component of the resonance frequency in the sound equipment before the speaker may be provided. Then, resonance is less likely to occur in this loudspeaker space, and it is easier to hear music and speech from speed.
ディップフィル夕によってかかる効果を得るためには、 この拡声空間の共鳴周 波数を除去周波数とするようにディップフィル夕の周波数特性を決定しなければ ならない。  In order to obtain such an effect by dip-filling, the frequency characteristics of the dip-filling must be determined so that the resonance frequency of this loudspeaker space is used as the removal frequency.
従来は、 音響設備のオペレータや測定者が自らの聴覚に頼ってスピーカの拡声 音や共鳴音を聞き分けて共鳴周波数を判断し、 この共鳴周波数を除去周波数とし てディップフィルタに設定していた。 そして、 共鳴が生じない程度にディップの 減衰レベル （深さ） やその尖鋭度 （Q) を設定していた。 ^ このような聞き分けによって共鳴周波数を知ることが出来たとしても、 ディッ プフィル夕の周波数特性を設定するのは容易ではない。 特に、 ディップの減衰レ ベル （深さ） や尖鋭度 （Q) を適切に設定することは容易ではない。 これらを適 切に設定しないと、 音響装置の音質を損ねたり、 スピーカからの音楽や話声が聞 きとりにくくなつたりする。 Conventionally, acoustic equipment operators and measurers have relied on their own hearing to distinguish the loudspeakers and resonances of the loudspeakers, determine the resonance frequency, and set this resonance frequency as a removal frequency in the dip filter. Then, the attenuation level (depth) of the dip and its sharpness (Q) were set so that resonance did not occur. ^ Even if you can know the resonance frequency by such a distinction, it is not easy to set the frequency characteristics of the dip fill. In particular, it is not easy to properly set the dip attenuation level (depth) and sharpness (Q). If these are not set properly, the sound quality of the audio device will be impaired, and it will be difficult to hear music and speech from the speakers.
このようなことが生じないように適切にディップの減衰レベルや尖鋭度を設定 するには、 ある程度の熟練、 経験を要する。 また、 このような熟練、 経験に頼る 設定であれば、 必ずしもこれらのファクタ一 （ディップの減衰レベルや尖鋭度） を適切に設定することはできない。 さらにこのことが、 拡声空間等に設置される 音響設備の自動測定 ·自動調整のための障害にもなつていた。  It takes some skill and experience to properly set the dip attenuation level and sharpness so that this does not occur. Also, if the setting relies on such skill and experience, it is not always possible to properly set one of these factors (dip attenuation level and sharpness). This also hindered the automatic measurement and adjustment of sound equipment installed in loudspeaker spaces.
[発明の開示] [Disclosure of the Invention]
本願発明は上記問題点に鑑み、 経験や熟練を必要とすることなく、 ディップフ ィル夕の特性を適切に決定することができるような、 ディップフィル夕の周波数 特性決定方法を提供することを目的とする。  The present invention has been made in view of the above problems, and has as its object to provide a method for determining the frequency characteristics of a dip filter, which can appropriately determine the characteristics of the dip filter without requiring experience or skill. And
上記課題を解決するために、 この出願に係るディップフィル夕の周波数特性決 定方法は、 共鳴空間で検出された共鳴周波数のうちの、 所定周波数以下のものは ディップの中心周波数から除外し、 該所定周波数を超えるもののみをディップの 中心周波数として決定し、 該共鳴空間に配置されたスピーカから所定の測定用信 号を拡声させ、 該共鳴空間に配置されたマイクロホンによって受音して得られる 測定値に基づき、 基礎振幅周波数特性を求め、 該測定値に基づき、 該基礎振幅周 波数特性よりも周波数軸上での平滑度が大きい目標振幅周波数特性を求め、 第 1 面積に第 2面積が略一致するように該ディップの減衰レベル および尖鋭度を一 次決定し、 該第 1面積は、 振幅レベルを表す対数軸を縦軸とし周波数を表す軸を 横軸とした振幅周波数特性図上に該基礎振幅周波数特性の曲線と該目標振幅周波 数特性の曲線とを表したときの、 第 1周波数から第 2周波数までの周波数範囲に おいて、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線とに囲まれ るエリアの面積であり、 該第 1周波数は、 該基礎振幅周波数特性の曲線と該目標 振幅周波数特性の曲線とが交差し、 かつ、 該ディップの中心周波数よりも低い周 0 波数のうちの、 該ディップの中心周波数に最も近い周波数であり、 該第 2周波数 は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線とが交差し、 か つ、 該ディップの中心周波数よりも高い周波数のうちの、 該ディップの中心周波 数に最も近い周波数であり、 該第 2面積は、 振幅レベルを表す対数軸を縦軸とし 周波数を表す軸を横軸とした振幅周波数特性図上に該ディップの特性を表したと きの、 該ディップの面積である。 In order to solve the above-mentioned problem, a method of determining a frequency characteristic of a dip filter according to the present application includes, among resonance frequencies detected in a resonance space, those below a predetermined frequency are excluded from the center frequency of the dip. Only a frequency exceeding a predetermined frequency is determined as a center frequency of the dip, a predetermined measurement signal is loudspeaked from a speaker arranged in the resonance space, and a measurement is obtained by receiving a sound by a microphone arranged in the resonance space. A basic amplitude frequency characteristic is obtained based on the value, a target amplitude frequency characteristic having a greater smoothness on the frequency axis than the basic amplitude frequency characteristic is obtained based on the measured value, and the second area is approximately equal to the first area. The attenuation level and sharpness of the dip are primarily determined so as to match, and the first area has a logarithmic axis representing an amplitude level as a vertical axis and an axis representing a frequency as a horizontal axis. When the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are represented on the amplitude frequency characteristic diagram, the basic amplitude frequency characteristic is obtained in the frequency range from the first frequency to the second frequency. An area surrounded by the curve and the curve of the target amplitude frequency characteristic, wherein the first frequency is such that the curve of the basic amplitude frequency characteristic intersects with the curve of the target amplitude frequency characteristic; Frequency lower than the center frequency of 0 of the wave numbers, the frequency closest to the center frequency of the dip, and the second frequency is such that the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect, and The frequency closest to the center frequency of the dip among the frequencies higher than the center frequency, and the second area is an amplitude frequency having a logarithmic axis representing the amplitude level as a vertical axis and an axis representing the frequency as a horizontal axis. This is the area of the dip when the characteristics of the dip are represented on the characteristic diagram.
かかる方法によれば、 ディップフィル夕に設定すべき適切な特性を、 客観的に 決定することができる。 また、 この方法において一次決定されたディップの減衰 レベル および尖鋭度をディップフィル夕に設定し、 拡声空間の音響システムに このディップフィル夕を用いると、 そのディップの中心周波数近傍の振幅周波数 特性は、 目標振幅周波数特性に極めて近い特性となる。 よって、 音質を損なうこ となく共鳴を防止することができる。 また、 共鳴空間で検出された共鳴周波数の うちの、 所定周波数以下のものはディップの中心周波数から除外し 該所定周波 数を超えるもののみをディップの中心周波数として決定するので、 共鳴空間の音 響システムにこのディップフィル夕を用いると、 共鳴空間において拡声される音 楽や話声が量感の乏しいものとなることを防止できる。  According to this method, it is possible to objectively determine an appropriate characteristic to be set in the dip fill. Also, by setting the attenuation level and the sharpness of the dip determined primarily in this method to the dip fill, and using this dip fill in the sound system of the loudspeaker space, the amplitude frequency characteristic near the center frequency of the dip becomes The characteristic is very close to the target amplitude frequency characteristic. Therefore, resonance can be prevented without deteriorating sound quality. Also, of the resonance frequencies detected in the resonance space, those below a predetermined frequency are excluded from the center frequency of the dip, and only those exceeding the predetermined frequency are determined as the center frequency of the dip. The use of this dip-fill system in a system can prevent the volume of music and speech louder in the resonance space from becoming poor.
上記方法において、 該所定周波数を、 2 5 0 H z以下の周波数としてもよい。 音楽や話声の量感に影響を与えやすい 2 5 0 H z以下の周波数成分を対象とする ことにより、 共鳴空間において拡声される音楽や話声が量感の乏しいものとなる ことを防止できる。 例えば、 2 5 0 H z以下の周波数である： f a (H z )を基準周 波数とし、 共鳴空間で検出された共鳴周波数のうちの f a (H z )以下のものはデ イッブの中心周波数から除外し、 ： f a (H z )を超えるもののみをディップの中心 周波数として決定するようにしてもよい。  In the above method, the predetermined frequency may be a frequency equal to or lower than 250 Hz. By targeting the frequency components of 250 Hz or less that easily affect the volume of music and voice, it is possible to prevent the volume of music and voice louder in the resonance space from becoming poor. For example, frequencies below 250 Hz: Let fa (H z) be the reference frequency, and those of the resonance frequencies detected in the resonance space that are lower than fa (H z) are calculated from the center frequency of the device. It may be excluded and only those exceeding fa (Hz) may be determined as the center frequency of the dip.
また、 上記課題を解決するために、 この出願に係るディップフィルタの周波数 特性決定方法は、 共鳴空間で検出された共鳴周波数をディップの中心周波数とし て決定し、 該共鳴空間に配置されたスピーカから所定の測定用信号を拡声させ、 該共鳴空間に配置されたマイクロホンによって受音して得られる測定値に基づき、 基礎振幅周波数特性を求め、 該測定値に基づき、 該基礎振幅周波数特性よりも周 波数軸上での平滑度が大きい目標振幅周波数特性を求め、 第 1面積に第 2面積が 略一致するように該ディップの減衰レベル および尖鋭度を一次決定し、 該一次 決定された該減衰レベルが所定レベル未満であるとき、 レベルをさらに大きくす るように該減衰レベルを二次決定し、 該第 1面積は、 振幅レベルを表す対数軸を 縦軸とし周波数を表す軸を横軸とした振幅周波数特性図上に該基礎振幅周波数特 性の曲線と該目標振幅周波数特性の曲線とを表したときの、 第 1周波数から第 2 周波数までの周波数範囲において、 該基礎振幅周波数特性の曲線と該目標振幅周 波数特性の曲線とに囲まれるエリアの面積であり、 該第 1周波数は、 該基礎振幅 周波数特性の曲線と該目標振幅周波数特性の曲線とが交差し、 かつ、 該ディップ の中心周波数よりも低い周波数のうちの、 該ディップの中心周波数に最も近い周 波数であり、 該第 2周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数 特性の曲線とが交差し、 かつ、 該ディップの中心周波数よりも高い周波数のうち の、 該ディップの中心周波数に最も近い周波数であり、 該第 2面積は、 振幅レべ ルを表す対数軸を縦軸とし周波数を表す軸を横軸とした振幅周波数特性図上に該 ディップの特性を表したときの、 該ディップの面積である。 Further, in order to solve the above-mentioned problems, a method for determining a frequency characteristic of a dip filter according to the present application determines a resonance frequency detected in a resonance space as a center frequency of the dip, and uses a speaker arranged in the resonance space to determine a resonance frequency. A predetermined measurement signal is loudspeaked, and a fundamental amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space. The target amplitude frequency characteristic with a large smoothness on the wavenumber axis is found, and the second area is The attenuation level and the sharpness of the dip are primarily determined so as to substantially match, and when the primarily determined attenuation level is less than a predetermined level, the attenuation level is secondarily determined to further increase the level. The first area is obtained by dividing the basic amplitude frequency characteristic curve and the target amplitude frequency characteristic curve on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the vertical axis and the frequency axis as the horizontal axis. In the frequency range from the first frequency to the second frequency when expressed, it is the area of the area surrounded by the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic, and the first frequency is The curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect, and the frequency closest to the center frequency of the dip among the frequencies lower than the center frequency of the dip. The second frequency is such that the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect, and which is closest to the center frequency of the dip among the frequencies higher than the center frequency of the dip The second area is the frequency of the dip when the characteristic of the dip is represented on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the vertical axis and the axis representing the frequency as the horizontal axis. Area.
かかる方法によれば、 ディップフィル夕に設定すべき適切な特性を、 客観的に 決定することができる。 また、 この方法において一次決定されたディップの減衰 レベル および尖鋭度をディップフィル夕に設定し、 拡声空間の音響システムに このディップフィルタを用いると、 そのディップの中心周波数近傍の振幅周波数 特性は、 目標振幅周波数特性に極めて近い特性となる。 よって、 音質を損なうこ となく共鳴を防止することができる。 また、 一次決定された減衰レベルが所定レ ベル以下であるときには、 二次決定によってさらに大きなレベルとなるように減 衰レベルが決定される。 よって、 共鳴空間の音響システムにこのディップフィル 夕を用いると、 共鳴空間において共鳴が防止されていると、 聴感上、 感ずること ができる。  According to this method, it is possible to objectively determine an appropriate characteristic to be set in the dip fill. Also, if the attenuation level and the sharpness of the dip determined first in this method are set to dip fill, and this dip filter is used in the sound system of the loudspeaker space, the amplitude frequency characteristic near the center frequency of the dip becomes the target The characteristic is very close to the amplitude frequency characteristic. Therefore, resonance can be prevented without deteriorating sound quality. When the primary determined attenuation level is equal to or lower than the predetermined level, the secondary determination determines the attenuation level so as to be higher. Therefore, when this dip filter is used for the acoustic system in the resonance space, it is possible to hear the sound if the resonance is prevented in the resonance space.
上記方法において、 一次決定された減衰レベルが所定レベル未満であるとき、 該二次決定において、 該減衰レベルを該所定レベルにするように決定してもよい。 例えば、 一次決定による減衰レベルが L h (d B)未満であるとき二次決定によつ てこの減衰レベルを L h (d B)とするように決定してもよい。  In the above method, when the primary determined attenuation level is less than a predetermined level, the secondary determination may include determining the attenuation level to be the predetermined level. For example, when the attenuation level determined by the primary determination is less than L h (dB), the attenuation level may be determined to be L h (dB) by the secondary determination.
また、 上記方法において、 所定周波数以下の周波数を中心周波数とするディッ プにおいてのみ、 減衰レベルに対して二次決定を行うようにしてもよい。 Further, in the above method, a ditto having a frequency equal to or lower than a predetermined frequency as a center frequency. Only at the second stage, a secondary decision may be made on the attenuation level.
かかる方法によれば、 所定周波数よりも高い周波数の成分を除去するディップ の減衰レベルは、 二次決定によって大きくされることがなくなる。 ある周波数よ りも高い周波数の成分は音声の明瞭度に対する寄与が大きいので、 かかる方法で 決定されたディップ特性をディップフィル夕に設定すると、 音声の明瞭度が低下 することはなくなる。  According to such a method, the attenuation level of the dip for removing a component having a frequency higher than the predetermined frequency is not increased by the secondary determination. Since components at frequencies higher than a certain frequency have a large contribution to speech intelligibility, setting the dip characteristics determined by such a method to dip-filling will not reduce speech intelligibility.
また、 上記課題を解決するために、 この出願に係るディップフィル夕の周波数 特性決定方法は、 共鳴空間で検出された共鳴周波数をディップの中心周波数とし て決定し、 該共鳴空間に配置されたスピーカから所定の測定用信号を拡声させ、 該共鳴空間に配置されたマイクロホンによって受音して得られる測定値に基づき、 基礎振幅周波数特性を求め、 該測定値に基づき、 該基礎振幅周波数特性よりも周 波数軸上での平滑度が大きい目標振幅周波数特性を求め、 第 1面積に第 2面積が 略一致するように該ディップの減衰レベル および尖鋭度を一次決定し、 該一次 決定された該尖鋭度が所定値を超えるとき、 その値をさらに小さくするように該 尖鋭度を二次決定し、 該第 1面積は、 振幅レベルを表す対数軸を縦軸とし周波数 を表す軸を横軸とした振幅周波数特性図上に該基礎振幅周波数特性の曲線と該目 標振幅周波数特性の曲線とを表したときの、 第 1周波数から第 2周波数までの周 波数範囲において、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とに囲まれるエリアの面積であり、 該第 1周波数は、 該基礎振幅周波数特性の曲 線と該目標振幅周波数特性の曲線とが交差し、 かつ、 該ディップの中心周波数よ りも低い周波数のうちの、 該ディップの中心周波数に最も近い周波数であり、 該 第 2周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線とが 交差し、 かつ、 該ディップの中心周波数よりも高い周波数のうちの、 該ディップ の中心周波数に最も近い周波数であり、 該第 2面積は、 振幅レベルを表す対数軸 を縦軸とし周波数を表す軸を横軸とした振幅周波数特性図上に該ディップの特性 を表したときの、 該ディップの面積である。  Further, in order to solve the above-mentioned problem, a method for determining a frequency characteristic of a dip filter according to the present application determines a resonance frequency detected in a resonance space as a center frequency of the dip, and a speaker arranged in the resonance space. , A predetermined measurement signal is loudspeaked, and a basic amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space. A target amplitude frequency characteristic having a large degree of smoothness on the frequency axis is obtained, and an attenuation level and a sharpness of the dip are primarily determined so that the second area substantially matches the first area, and the primary determined sharpness is determined. When the degree exceeds a predetermined value, the sharpness is secondarily determined so as to further reduce the value, and the first area is an axis representing a logarithmic axis representing the amplitude level and an axis representing the frequency. When the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are shown on the amplitude frequency characteristic diagram on the horizontal axis, the basic amplitude is shown in the frequency range from the first frequency to the second frequency. An area surrounded by the curve of the frequency characteristic and the curve of the target amplitude frequency characteristic, wherein the first frequency is such that the curve of the basic amplitude frequency characteristic intersects with the curve of the target amplitude frequency characteristic, and The frequency closest to the center frequency of the dip among the frequencies lower than the center frequency of the dip, and the second frequency has a curve of the basic amplitude frequency characteristic and a curve of the target amplitude frequency characteristic. The frequency that intersects and is higher than the center frequency of the dip is the frequency closest to the center frequency of the dip, and the second area has a logarithmic axis representing an amplitude level as a vertical axis and a frequency When representing the characteristics of the dip on the amplitude-frequency characteristic diagram of the shaft and the horizontal axis representing the is the area of the dip.
かかる方法によれば、 ディップフィル夕に設定すべき適切な特性を、 客観的に 決定することができる。 また、 この方法において一次決定されたディップの減衰 レベル および尖鋭度をディップフィルタに設定し、 拡声空間の音響システムに このディップフィルタを用いると、 そのディップの中心周波数近傍の振幅周波数 特性は、 目標振幅周波数特性に極めて近い特性となる。 よって、 音質を損なうこ となく共鳴を防止することができる。 ここで、 尖鋭度が大きすぎると、 ディップ フィルタにその特性を設定したとき、 聴感上で違和感を感ずることがある。 尖鋭 度が大きいほど、 ディップフィル夕の周波数特性におけるディップの中心周波数 近傍での位相の変化が大きくなるからである。 つまり、 周波数軸上における位相 の急激な変化が、 聴感上の違和感を与えるのである。 従って、 一次決定された尖 鋭度が所定値を超えるときには、 二次決定によってその値がさらに小さくなるよ うに該尖鋭度が決定される。 よって、 共鳴空間の音響システムにこのディップフ ' ィルタを用いると、 共鳴空間において音質が大きく損なわれることはなく、 聴感 上で違和感を感ずることはなくなる。 According to this method, it is possible to objectively determine an appropriate characteristic to be set in the dip fill. In addition, the attenuation level and the sharpness of the dip determined in this way are set in the dip filter, and applied to the sound system of the loudspeaker space. When this dip filter is used, the amplitude frequency characteristic near the center frequency of the dip is very close to the target amplitude frequency characteristic. Therefore, resonance can be prevented without deteriorating sound quality. If the sharpness is too high, you may feel uncomfortable when you set the characteristics of the dip filter. This is because the greater the sharpness, the greater the change in phase near the center frequency of the dip in the frequency characteristics of the dip fill. In other words, a sudden change in the phase on the frequency axis gives a sense of incongruity in hearing. Therefore, when the primary determined sharpness exceeds a predetermined value, the secondary determination determines the sharpness so that the value is further reduced. Therefore, if this dip filter is used for the acoustic system in the resonance space, the sound quality in the resonance space will not be significantly impaired, and the listener will not feel uncomfortable.
上記方法において、 一次決定された尖鋭度が所定値を超えるときには、 尖鋭度 をその所定値にするように二次決定してもよい。  In the above method, when the primary determined sharpness exceeds a predetermined value, the secondary determination may be made such that the sharpness is set to the predetermined value.
また、 上記方法において、 目標振幅周波数特性はいかなる方法によって平滑化 されたものであってもよいが、 測定された振幅周波数特性を周波数軸上で移動平 均することによって平滑化されたものであってもよい。  In the above method, the target amplitude frequency characteristic may be smoothed by any method. However, the target amplitude frequency characteristic is smoothed by moving and averaging the measured amplitude frequency characteristic on the frequency axis. May be.
また上記方法において、 該一次決定において、 該ディップの減衰レベルを、 該 ディップの中心周波数における該基礎振幅周波数特性と該目標振幅周波数特性の 振幅レベル差に略一致するように決定し、 該ディップの尖鋭度を、 該第 1面積に 該第 2面積が略一致するように決定してもよい。  In the above method, in the primary determination, an attenuation level of the dip is determined so as to substantially match an amplitude level difference between the basic amplitude frequency characteristic and the target amplitude frequency characteristic at a center frequency of the dip; The sharpness may be determined such that the first area is substantially equal to the second area.
基礎振幅周波数特性に、 かかる方法で決定されたディップ特性を作用させると、 目標振幅周波数特性に極めて近い特性となる。  When the dip characteristic determined by such a method is applied to the basic amplitude frequency characteristic, the characteristic becomes very close to the target amplitude frequency characteristic.
また上記方法において、 該第 1周波数から該第 2周波数までの周波数範囲に、 該共鳴空間で検出された複数の共鳴周波数が含まれるとき、 該複数の共鳴周波数 の内の、 第 2の振幅周波数特性の振幅レベルが最も大きな共鳴周波数を、 該ディ ップの中心周波数として決定し、 それ以外の共鳴周波数を該ディップの中心周波 数とはしないように決定し、 該第 2の振幅周波数特性は、 該スピーカから該測定 用信号と該マイクロホンの出力信号との合成信号を拡声させて、 該マイクロホン によって受音して得られる振幅周波数特性であってもよい。 飞 かかる方法によれば、 ディップフィル夕に必要以上の数のディップが設定され ることを回避できる。 Further, in the above method, when the frequency range from the first frequency to the second frequency includes a plurality of resonance frequencies detected in the resonance space, a second amplitude frequency of the plurality of resonance frequencies The resonance frequency having the largest amplitude level of the characteristic is determined as the center frequency of the dip, and the other resonance frequencies are determined so as not to be the center frequency of the dip. An amplitude frequency characteristic obtained by loudspeaking a composite signal of the measurement signal and the output signal of the microphone from the speaker and receiving the sound by the microphone may be used. 飞 According to this method, it is possible to avoid setting an excessive number of dips in the dip fill.
また上記方法において、 第 1の振幅周波数特性と第 2の振幅周波数特性との比 較に基づいて、 該共鳴空間の共鳴周波数を検出し、 該第 1の振幅周波数特性は、 該測定値に基づいて得られる振幅周波数特性であり、 該第 2の振幅周波数特性は、 該スピーカから該測定用信号と該マイクロホンの出力信号との合成信号を拡声さ せて、 該マイクロホンによって受音して得られる振幅周波数特性であるようにし てもよい。  In the above method, the resonance frequency of the resonance space is detected based on a comparison between the first amplitude frequency characteristic and the second amplitude frequency characteristic, and the first amplitude frequency characteristic is determined based on the measured value. The second amplitude frequency characteristic is obtained by loudspeaking a composite signal of the measurement signal and the output signal of the microphone from the speaker and receiving the sound by the microphone. The amplitude frequency characteristic may be used.
かかる方法における第 2の振幅周波数特性は、 マイクロホンの出力信号がスピ 一力へ入力されるというフィードバックループを含む系の振幅周波数特性である。 このフィードパックループにより、 第 2の振幅周波数特性では、 第 1の振幅周波 数特性に比べ、 共鳴空間の共鳴の特性がより大きく強調されて表れる。 よって、 第 1の振幅周波数特性と第 2の振幅周波数特性とを比較することにより、 共鳴空 間の共鳴周波数を正確に検出することができる。  The second amplitude frequency characteristic in such a method is an amplitude frequency characteristic of a system including a feedback loop in which the output signal of the microphone is input to the speaker. With this feedback loop, the resonance characteristics of the resonance space appear more emphasized in the second amplitude frequency characteristics than in the first amplitude frequency characteristics. Therefore, by comparing the first amplitude frequency characteristic and the second amplitude frequency characteristic, the resonance frequency of the resonance space can be accurately detected.
また上記方法において、 該第 1の振幅周波数特性と該第 2の振幅周波数特性と の差分から、 該第 1の振幅周波数特性に比べて該第 2の振幅周波数特性の方が振 幅が大きいピーク点の周波数を該共鳴空間の共鳴周波数として検出するようにし てもよい。  Further, in the above method, a peak having a larger amplitude in the second amplitude frequency characteristic than in the first amplitude frequency characteristic is obtained from a difference between the first amplitude frequency characteristic and the second amplitude frequency characteristic. The frequency of the point may be detected as the resonance frequency of the resonance space.
また上記方法において、 該測定用信号としては正弦波スイープ信号が特に有効 である。  In the above method, a sine wave sweep signal is particularly effective as the measurement signal.
本発明の上記目的、 他の目的、 特徴、 及び利点は、 添付図面参照の下、 以下の 好適な実施態様の詳細な説明から明らかにされる。  The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.
[図面の簡単な説明] [Brief description of drawings]
第 1図は、 拡声空間に設置された音響システムの概略構成図である。  FIG. 1 is a schematic configuration diagram of an acoustic system installed in a loudspeaker space.
第 2図は、 拡声空間において振幅周波数特性を測定するためのシステムの概略 ブロック図である。  FIG. 2 is a schematic block diagram of a system for measuring amplitude frequency characteristics in a loudspeaker space.
第 3図は、 拡声空間において振幅周波数特性を測定するためのシステムの概略 ブロック図である。 。 FIG. 3 is a schematic block diagram of a system for measuring amplitude frequency characteristics in a loudspeaker space. .
o 第 4図は、 第 2図のシステムによって測定された拡声空間の第 1の振幅周波数 特性と、 第 3図のシステムによって測定された拡声空間の第 2の振幅周波数特性 とを模式的に示す特性図である。  o Fig. 4 schematically shows the first amplitude frequency characteristic of the loudspeaker space measured by the system of Fig. 2 and the second amplitude frequency characteristic of the loudspeaker space measured by the system of Fig. 3 It is a characteristic diagram.
第 5図は、 第 4図の曲線 C aの第 1の振幅周波数特性と曲線 C bの第 2の振幅周 波数特性との振幅レベル差を示す周波数特性図である。  FIG. 5 is a frequency characteristic diagram showing an amplitude level difference between a first amplitude frequency characteristic of a curve C a in FIG. 4 and a second amplitude frequency characteristic of a curve C b.
第 6図は、 第 4図の周波数特性図から曲線 C bのみを取り出した周波数特性図 である。  FIG. 6 is a frequency characteristic diagram obtained by extracting only the curve Cb from the frequency characteristic diagram of FIG.
第 7図は、 基礎振幅周波数特性の曲線 C aと目標振幅周波数特性の曲線 C dと を示す周波数特性図である。  FIG. 7 is a frequency characteristic diagram showing a curve C a of the basic amplitude frequency characteristic and a curve C d of the target amplitude frequency characteristic.
第 8図は、 周波数 f 61から周波数 f 62までの周波数範囲に候補となる 3つの周 波数が存在する場合を示す周波数特性図である。  FIG. 8 is a frequency characteristic diagram showing a case where three candidate frequencies exist in a frequency range from a frequency f61 to a frequency f62.
第 9図は、 中心周波数が周波数 f 2であるディップの振幅周波数特性図である。  FIG. 9 is an amplitude frequency characteristic diagram of a dip whose center frequency is frequency f2.
[発明を実施するための最良の形態] [Best Mode for Carrying Out the Invention]
本願発明の一実施形態たるディップフィルタの周波数特性決定方法を、 以下に 図面を参照しつつ説明する。  A method for determining a frequency characteristic of a dip filter according to an embodiment of the present invention will be described below with reference to the drawings.
第 1図は、 拡声空間 （例えば、 コンサートホールや体育館） 40に設置された音 響システムの概略構成図である。 この音響システムは、 音源装置 2と、 ディップフ ィル夕 4と、 アンプ 12と、 スピーカ 13とを備えている。 音源装置 2は、 例えば音楽 C Dを再生するための C Dプレーヤのような演奏器機であってもよいし、 マイク 口ホンであってもよい。 第 1図では音源装置 2を拡声空間 40の外側に表しているが、 音源装置 2は拡声空間 40内に設置されていてもよい。 例えば、 音源装置 2は、 拡声 空間 40内に設置されたマイクロホンであってもよい。 ディップフィル夕 4は、 音源 装置 2からの信号から特定の周波数の信号成分を除去してアンプ 12に送出するため のものである。 ディップフィルタ 4からの信号はアンプ 12で増幅されてスピーカ 1 3に送出され、 拡声空間 40においてスピーカ 13から拡声される。  FIG. 1 is a schematic configuration diagram of a sound system installed in a public space (for example, a concert hall or a gymnasium) 40. This acoustic system includes a sound source device 2, a dip filter 4, an amplifier 12, and a speaker 13. The sound source device 2 may be, for example, a playing device such as a CD player for reproducing music CD, or a microphone and a microphone. Although the sound source device 2 is shown outside the sound space 40 in FIG. 1, the sound source device 2 may be installed in the sound space 40. For example, the sound source device 2 may be a microphone installed in the loudspeaker space 40. The dip filter 4 is for removing a signal component of a specific frequency from the signal from the sound source device 2 and transmitting the signal component to the amplifier 12. The signal from the dip filter 4 is amplified by the amplifier 12 and transmitted to the speaker 13, and is amplified from the speaker 13 in the sound space 40.
この拡声空間 40が共鳴周波数を有するとき、 スピ一力 13からの拡声音に共鳴周 波数の成分が多く含まれると、 拡声空間 40において共鳴が起こり、 スピーカ 13か らの音楽や話声が聞き取りにくくなる。 しかし、 この音響システムにおいて、 デ g ィップフィル夕 4に適切な周波数特性を設定すると、 スピーカ 13からの拡声音の音 質を損なうことなく、 拡声空間 40における共鳴を防止することができる。 When the loudspeaker space 40 has a resonance frequency, if the loudspeaker sound from the speed 13 contains many components of the resonance frequency, resonance occurs in the loudspeaker space 40, and the music and speech from the speaker 13 are heard. It becomes difficult. However, in this acoustic system, By setting an appropriate frequency characteristic for the g- fill filter 4, resonance in the loudspeaker space 40 can be prevented without deteriorating the sound quality of the loudspeaker sound from the speaker 13.
本実施形態では、 ディップフィルタ 4に設定すべき周波数特性を決定するのであ るが、 まず最初に第 2〜 5図を参照しつつ、 共鳴空間 40において共鳴周波数を検 出する方法 ·装置を説明する。  In the present embodiment, the frequency characteristic to be set in the dip filter 4 is determined. First, a method and an apparatus for detecting a resonance frequency in the resonance space 40 will be described with reference to FIGS. I do.
第 2図は、 拡声空間 （例えば、 コンサートホールや体育館） 40において振幅周 波数特性を測定するためのシステム Aの概略ブロック図である。 このシステム A は、 測定用信号を発する音源手段たる発信器 1 1と、 この発信器 1 1が発する信号を 入力して電力増幅するアンプ 1 2と、 このアンプ 12の出力信号を入力して拡声する スピーカ 13と、 スピーカ 13が放射する拡声音を受音するマイクロホン 14と、 マイ クロホン 14の受音信号を入力する測定器 15とを備える。 マイクロホン 14は騒音計 であってもよい。  FIG. 2 is a schematic block diagram of a system A for measuring amplitude frequency characteristics in a public space (for example, a concert hall or a gymnasium) 40. The system A includes a transmitter 11 as a sound source for generating a signal for measurement, an amplifier 12 for inputting a signal generated by the transmitter 11 and amplifying power, and a loudspeaker receiving an output signal of the amplifier 12 and inputting a signal. A speaker 13, a microphone 14 for receiving a loud sound radiated by the speaker 13, and a measuring device 15 for inputting a sound reception signal of the microphone 14. The microphone 14 may be a sound level meter.
スピーカ 13とマイクロホン 14とは、 拡声空間 40内に配置されている。 マイクロ ホン 14は拡声空間 40内において、 スピーカ 13から充分に距離を置いている。 マイ クロホン 14は、 スピーカ 13からの直接音に対して、 拡声空間 40内における反射音 を充分大きなレベルで受音できる位置に配置されている。  The speaker 13 and the microphone 14 are arranged in a sound space 40. The microphone 14 is sufficiently far from the speaker 13 in the sound space 40. The microphone 14 is arranged at a position where the reflected sound in the loudspeaker space 40 can be received at a sufficiently large level with respect to the direct sound from the speaker 13.
発信器 1 1は測定用信号として、 周波数が時間的に変化するような正弦波信号を 発する。 つまり発信器 11は、 正弦波スイープ信号を発信する。 この正弦波スィー プ信号では、 周波数スイープ中の各時点において正弦波のレベルは一定である。 測定器 15は、 時間的に中心周波数が変化するようなバンドパスフィル夕を有し ている。 このバンドパスフィルタは、 発信器 1 1が発信する正弦波スイープ信号の 周波数の時間的変化に対応して、 中心周波数を時間的に変化させる。 よって測定 器 1 5は、 マイクロホン 14から入力する受音信号のレベルをこのバンドパスフィル 夕を介して検出することにより、 その時点における周波数の振幅特性を測定する ことができる。  The transmitter 11 emits a sine wave signal whose frequency changes with time as a measurement signal. That is, the transmitter 11 transmits a sine wave sweep signal. In the sine wave sweep signal, the level of the sine wave is constant at each point in the frequency sweep. The measuring device 15 has a bandpass filter whose center frequency changes with time. This band-pass filter temporally changes the center frequency in response to the temporal change of the frequency of the sine wave sweep signal transmitted by the transmitter 11. Therefore, measuring instrument 15 can measure the amplitude characteristic of the frequency at that time by detecting the level of the sound reception signal input from microphone 14 through this bandpass filter.
第 3図は、 拡声空間 40において振幅周波数特性を測定するためのシステム Bの 概略ブロック図である。 このシステム Bは、 第 2図のシステム Aに、 ある信号の 合成のための経路を付加しただけのものである。 つまり第 3図のシステム Bは、 測定用信号を発する音源手段たる発信器 1 1と、 ミキシング装置 16と、 ミキシング ^ 装置 16の出力信号を入力してこの信号を電力増幅するアンプ 12と、 このアンプ 12 の出力信号を入力して拡声するスピーカ 13と、 スピーカ 13が放射する拡声音を受 音するマイクロホン 14と、 マイクロホン 14の受音信号を入力する測定器 15とを備 える。 FIG. 3 is a schematic block diagram of a system B for measuring the amplitude frequency characteristic in the loudspeaker space 40. This system B is obtained by adding a path for synthesizing a certain signal to the system A shown in FIG. In other words, the system B shown in FIG. 3 is composed of a transmitter 11 serving as a sound source for emitting a signal for measurement, a mixing device 16, ^ An amplifier 12 which receives the output signal of the device 16 and amplifies the power of the signal, a speaker 13 which receives the output signal of the amplifier 12 and loudspeaks, and a microphone 14 which receives the loudspeaker radiated by the speaker 13. And a measuring device 15 for inputting a sound reception signal of the microphone 14.
スピーカ 13とマイクロホン 14とは、 拡声空間 40内において、 第 2図のシステム Aにおけると同一の位置に配置されている。 第 3図のシステム Bにおける、 発信 器 11、 アンプ 12、 スピ一力 13、 マイクロホン 14、 測定器 15は、 第 2図のシステム Aにおけるこれら器機と同一のものである。  The speaker 13 and the microphone 14 are arranged at the same position in the loudspeaker space 40 as in the system A in FIG. The transmitter 11, the amplifier 12, the speed 13, the microphone 14, and the measuring instrument 15 in the system B in FIG. 3 are the same as those in the system A in FIG.
第 3図のシステム Bが第 2図のシステム Aと相違する点は、 第 2図のシステム Aでは、 アンプ 12が発信器 11から信号を入力していたのに対し、 第 3図のシステ ム Bでは、 アンプ 12がミキシング装置 16から信号を入力している点である。 第 3 図のミキシング装置 16は、 発信器 11からの測定用信号 （正弦波スイープ信号） と、 マイクロホン 14からの受音信号とを入力し、 これら入力した信号を合成 （ミキシ ング） し、 この合成信号 （ミキシング信号） を出力する。  The difference between the system B in Fig. 3 and the system A in Fig. 2 is that in the system A in Fig. 2, the amplifier 12 inputs the signal from the transmitter 11, whereas the system B in Fig. 3 In B, the amplifier 12 receives a signal from the mixing device 16. The mixing device 16 shown in FIG. 3 inputs the measurement signal (sine-wave sweep signal) from the transmitter 11 and the sound reception signal from the microphone 14, and synthesizes (mixes) these input signals. Outputs the composite signal (mixing signal).
以上、 第 2図のシステム Aによって拡声空間 40の振幅周波数特性を測定する方 法、 および、 第 3図のシステム Bによって拡声空間 40の振幅周波数特性を測定す る方法を説明したが、 以下では、 第 2図のシステム Aによって測定された拡声空 間 40の振幅周波数特性を第 1の振幅周波数特性と言い、 第 3図のシステム Bによ つて測定された拡声空間 40の振幅周波数特性を第 2の振幅周波数特性と言う。 第 4図は、 第 2図のシステム Aによって測定された拡声空間 40の第 1の振幅周 波数特性と、 第 3図のシステム Bによって測定された拡声空間 40の第 2の振幅周 波数特性とを模式的に示す特性図である。 第 4図においては縦軸、 横軸とも対数 軸であり、 縦軸は振幅レベルを横軸は周波数を示す。 なお、 「振幅レベル」 とは、 ある振幅値 （振幅の大きさ） の基準値 （基準の大きさ） に対する比の対数であり、 通常は 「d B」 を単位として表記する。 第 4図において実線で示す曲線 C aが、 第 2図のシステム Aによる第 1の振幅周波数特性であり、 破線で示す曲線 C bが、 第 3図のシステム Bによる第 2の振幅周波数特性である。  The method of measuring the amplitude frequency characteristics of the loudspeaker space 40 by the system A in FIG. 2 and the method of measuring the amplitude frequency characteristics of the loudspeaker space 40 by the system B in FIG. 3 have been described above. The amplitude frequency characteristic of the loudspeaker space 40 measured by the system A in FIG. 2 is called a first amplitude frequency characteristic, and the amplitude frequency characteristic of the loudspeaker space 40 measured by the system B in FIG. It is called the amplitude frequency characteristic of 2. FIG. 4 shows the first amplitude frequency characteristics of the loudspeaker space 40 measured by the system A in FIG. 2 and the second amplitude frequency characteristics of the loudspeaker space 40 measured by the system B in FIG. FIG. 3 is a characteristic diagram schematically showing In FIG. 4, both the vertical and horizontal axes are logarithmic axes, the vertical axis represents the amplitude level, and the horizontal axis represents the frequency. The “amplitude level” is the logarithm of the ratio of a certain amplitude value (magnitude of amplitude) to a reference value (magnitude of reference), and is usually expressed in units of “dB”. The curve C a shown by a solid line in FIG. 4 is the first amplitude frequency characteristic by the system A in FIG. 2, and the curve C b shown by a broken line is the second amplitude frequency characteristic by the system B in FIG. is there.
第 2図のシステム Aも第 3図のシステム Bも、 多数の周波数ボイントにおける 振幅値を測定する。 例えば測定対象となる周波数範囲において、 D bオクターブ ^ 間隔で振幅値を測定する（D bは 1よりも充分小さな正数）。 この多点 （多数の周 波数ポイント） での測定値を周波数軸上で平滑化せずに、 拡声空間 40の第 1，第 2 の振幅周波数特性として曲線 C a , C bに表しても良いし、 何らかの方法によって 周波数軸上で平滑化して、 曲線 C a , C bに表しても良い。 このときの平滑化の方 法には種々あるが、 例えば移動平均によって平滑化してもよい。 例えば、 多数の 周波数ボイントの測定値に対して周波数軸上で N cボイントの移動平均を施して もよい（N cは所定の自然数）。 なお、 曲線 C aとして平滑化されたものを用いる 場合は、 曲線 C bについても平滑化されたものを用いるのが好ましい。 この場合 にはさらに、 曲線 C aに関する平滑化の方法と同一の平滑化の方法によって曲線 C bを得ることが好ましい。 例えば曲線 C aを、 周波数軸上での N cポイントの 移動平均により得るのであれば、 曲線 C bも、 周波数軸上での N cポイントの移 動平均により得るのが好ましい。 Both system A in Fig. 2 and system B in Fig. 3 measure amplitude values at a number of frequency points. For example, in the frequency range to be measured, Db octave ^ Measure the amplitude value at intervals (D b is a positive number sufficiently smaller than 1). The measured values at these multiple points (many frequency points) may be represented on the curves C a and C b as the first and second amplitude frequency characteristics of the loudspeaker space 40 without being smoothed on the frequency axis. However, it may be smoothed on the frequency axis by some method and may be represented by curves C a and C b. There are various methods of smoothing at this time. For example, smoothing may be performed by a moving average. For example, a moving average of Nc points may be applied to a large number of measured values of frequency points on the frequency axis (Nc is a predetermined natural number). When using a smoothed curve C a, it is preferable to use a smoothed curve C b as well. In this case, it is preferable to obtain the curve Cb by the same smoothing method as that for the curve Ca. For example, if the curve C a is obtained by a moving average of N c points on the frequency axis, the curve C b is also preferably obtained by a moving average of N c points on the frequency axis.
第 4図の曲線 C aの第 1の振幅周波数特性は、 アンプ 12とスピーカ 13とマイクロ ホン 14とによる音響系の特性のみならず、 拡声空間 40の共鳴の特性をも包含する ものである。 第 4図の曲線 C bの第 2の振幅周波数特性も、 アンプ 12とスピーカ 1 3とマイクロホン 14とによる音響系の特性のみならず、 拡声空間 40の共鳴の特性を も包含するものであるが、 マイクロホン 14の出力信号がアンプ 12に入力されてス ピ一力 13から出力されるというフィ一ドバックル一プにより、 拡声空間 40の共鳴 の特性が曲線 C aの第 1の振幅周波数特性よりも大きく強調されて表れている。 よ つて、 両曲線 （曲線 C aと曲線 C b) との差から、 拡声空間 40の共鳴の特性を知る ことができる。  The first amplitude frequency characteristic of the curve Ca in FIG. 4 includes not only the characteristic of the acoustic system including the amplifier 12, the speaker 13, and the microphone 14, but also the characteristic of the resonance of the loudspeaker space 40. The second amplitude frequency characteristic of the curve Cb in FIG. 4 also includes not only the characteristic of the acoustic system by the amplifier 12, the speaker 13, and the microphone 14, but also the characteristic of the resonance of the loudspeaker space 40. However, due to the feedback buckle in which the output signal of the microphone 14 is input to the amplifier 12 and output from the speed 13, the resonance characteristic of the loudspeaker space 40 is lower than the first amplitude frequency characteristic of the curve Ca. It is greatly emphasized. Therefore, the resonance characteristics of the loudspeaker space 40 can be known from the difference between the two curves (the curves C a and C b).
第 5図に示す周波数特性曲線 C cは、 第 4図の曲線 Cbの特性から曲線 C aの特 性を差し引いた特性、 つまり、 曲線 C aの第 1の振幅周波数特性と曲線 C bの第 2 の振幅周波数特性との振幅レベル差を示すものである。 第 5図の曲線 C cにおい て正の方向にピークを示す周波数は、 周波数 f 1、 周波数 f 2 および 周波数 f 3である。 これら周波数が、 拡声空間 40の共鳴周波数である可能性が高い。 拡 声空間 40における共鳴周波数の数は一のみとは限らず、 複数である場合も多い。 よって、 周波数 f l、 ί 2、 f 3のうちの一のみが共鳴周波数である可能性もあ るし、 そのうちの複数が共鳴周波数である可能性もあるが、 第 5図の特性から、 ^ ^ 共鳴周波数たる可能性のある周波数を客観的に選び出すことができる。 The frequency characteristic curve C c shown in FIG. 5 is a characteristic obtained by subtracting the characteristic of the curve C a from the characteristic of the curve C b of FIG. 4, that is, the first amplitude frequency characteristic of the curve C a and the characteristic of the curve C b It shows the amplitude level difference from the amplitude frequency characteristic of No. 2. The frequencies that show peaks in the positive direction in the curve Cc in FIG. 5 are the frequency f1, the frequency f2, and the frequency f3. It is highly probable that these frequencies are the resonance frequencies of the loudspeaker space 40. The number of resonance frequencies in the loudspeaker space 40 is not limited to one, but is often plural. Therefore, only one of the frequencies fl, ί2, and f3 may be the resonance frequency, and more than one of them may be the resonance frequency. ^ ^ It is possible to objectively select the potential resonance frequency.
以上、 第 2〜 5図を参照しつつ、 共鳴空間 40において共鳴周波数を検出する方 法 ·装置を説明した。  The method and apparatus for detecting the resonance frequency in the resonance space 40 have been described above with reference to FIGS.
次に、 このようにして検出された共鳴周波数 （周波数 1 , f 2 , f 3 ) に基づ いて、 いかにして第 1図の音響システムのディップフィルタ 4の周波数特性を決定 するかを説明する。  Next, how to determine the frequency characteristics of the dip filter 4 of the acoustic system in FIG. 1 based on the resonance frequencies (frequency 1, f 2, f 3) thus detected will be described. .
第 4図の曲線 C aは、 第 2図のシステム Aによって得た拡声空間 40の第 1の振 幅周波数特性曲線であり、 上述のようにこの曲線 C aを用いて共鳴周波数を検出 した。 この曲線 C aの特性は、 以下で説明する第 1図の音響システムのディップ フィルタ 4の周波数特性決定のためにも用いる。 以下、 この曲線 C aの特性を 「基 礎振幅周波数特性」 という。 なお、 この 「基礎振幅周波数特性」 は、 第 2図のシ ステム Aによる多数の周波数ポイントでの測定値を周波数軸上で平滑化したもの であってもよいし、 平滑化していないものであってもよい。  The curve Ca in FIG. 4 is a first amplitude frequency characteristic curve of the loudspeaker space 40 obtained by the system A in FIG. 2, and the resonance frequency is detected using the curve Ca as described above. The characteristic of this curve C a is also used for determining the frequency characteristic of the dip filter 4 of the acoustic system of FIG. 1 described below. Hereinafter, the characteristic of the curve C a is referred to as “basic amplitude frequency characteristic”. Note that this “basic amplitude frequency characteristic” may be a value obtained by smoothing the measured values at a number of frequency points by the system A in FIG. 2 on the frequency axis or not. May be.
先に、 第 5図に示す周波数特性曲線じじから、 正の方向にピークを示す周波数 として、 周波数 f 1、 周波数 ί 2 および 周波数 f 3を得た。 これら周波数が 拡声空間 40の共鳴周波数である可能性が高い。  First, the frequency f1, the frequency ί2, and the frequency f3 were obtained from the frequency characteristic curve shown in FIG. 5 as the frequencies showing the peaks in the positive direction. It is highly possible that these frequencies are the resonance frequencies of the loudspeaker space 40.
しかし、 この周波数 （周波数 1、 周波数 f 2、 周波数 3 ) の中に; f d (H z )以下の周波数があれば、 その周波数 （f d (H z )以下の周波数） は、 ディップフ ィル夕 4に除去周波数として設定すべきディップの中心周波数の候補から除外する このように f d (H z )以下の周波数を候補から除外するのは次の理由による。 す なわち、 音楽や話声においてある周波数以下の周波数成分は、 その量感に与える 影響が大きいからである。 仮にある周波数以下の周波数をディップフィル夕 4にデ ィップの中心周波数として設定すると、 拡声空間 40において拡声される音楽や話 声が量感の乏しいものとなる。  However, if any of these frequencies (frequency 1, frequency f2, frequency 3) is less than fd (Hz), then that frequency (frequencies less than fd (Hz)) will be Exclude from the candidates for the center frequency of the dip to be set as the rejection frequency The frequency below fd (H z) is excluded from the candidates for the following reason. That is, frequency components below a certain frequency in music or speech have a large effect on the volume. If a frequency lower than a certain frequency is set as the center frequency of the dip in the dip fill 4, the volume of the music and voice loudspeaked in the loudspeaker space 40 becomes poor.
このような理由により、 f d (H z )以下の周波数を候補から除外するのである が、 第 5図において、 周波数 i l、 周波数' f 2、 周波数: f 3のいずれもが f d (H z )を超える周波数であるとすれば、 この段階ではいずれの周波数も、 ディップフ ィルタ 4に除去周波数として設定すべきディップの中心周波数の候補からは除外さ れない。 そしてこの中からさらに所定数の周波数のみを、 ディップフィルタ 4に除 去周波数として設定すべきディップの中心周波数の候補として選ぶ。 For this reason, frequencies below fd (Hz) are excluded from the candidates.In Fig. 5, all of frequency il, frequency 'f2, and frequency: f3 are fd (Hz). If so, at this stage, none of the frequencies is excluded from candidates for the center frequency of the dip to be set as the removal frequency in the dip filter 4. Then, only a predetermined number of frequencies are further filtered out by the dip filter 4. It is selected as a candidate for the center frequency of the dip to be set as the leaving frequency.
具体的には、 これら周波数の内から、 第 4図における曲線 C bの振幅レベルが 大きなものから順番に、 候補の周波数を選ぶ。  Specifically, candidate frequencies are selected from these frequencies in order from the one with the largest amplitude level of the curve Cb in FIG.
第 6図は、 第 4図から曲線 C bのみを取り出した特性図である。 第 6図におい ては縦軸、 横軸とも対数軸であり、 縦軸は振幅レベルを横軸は周波数を示す。 第 6図の曲線 C bでは、 周波数 f 2における振幅レベルが最も大きく、 f 3におけ る振幅レベルがその次に大きく、 f 1における振幅レベルがその次に大きい。 こ こで、 候補として選ぶ周波数の数を 「3」 とすると、 周波数 f 1、 周波数 f 2、 周波数 f 3のすべてが、 候補の周波数となる。  FIG. 6 is a characteristic diagram obtained by extracting only the curve Cb from FIG. In FIG. 6, both the vertical and horizontal axes are logarithmic axes, with the vertical axis representing amplitude level and the horizontal axis representing frequency. In the curve Cb in FIG. 6, the amplitude level at the frequency f2 is the highest, the amplitude level at the frequency f3 is the next highest, and the amplitude level at the frequency f1 is the next highest. Here, assuming that the number of frequencies to be selected as candidates is “3”, all of the frequencies f 1, f 2 and f 3 are candidate frequencies.
なお、 検出された共鳴周波数が多数ある場合には、 その全ての周波数をデイツ プフィル夕 4に除去周波数として設定すべきディップの中心周波数の候補として残 すのではなく、 所定数の周波数のみを候補として残すようにしてもよい。 例えば、 検出された共鳴周波数が多数 （例えば 2 0 0個以上） ある場合に、 N e個の周波 数のみを候補として残し、 残りの周波数は候補から除外するようにしてもよい（N eは 2 0 0より小さい所定の自然数）。 このとき、 いかなる周波数を候補として残 すかは、 例えば第 6図の曲線 C bにおいて、 振幅レベルの大きなものから優先的 に残すようにすればよい。  When there are a large number of detected resonance frequencies, all the frequencies are not left as candidates for the center frequency of the dip to be set as the removal frequency in the dip filter 4, but only a predetermined number of frequencies are candidate. You may leave as. For example, if there are a large number of detected resonance frequencies (for example, 200 or more), only N e frequencies may be left as candidates, and the remaining frequencies may be excluded from the candidates (N e is A predetermined natural number smaller than 200). At this time, what frequency should be left as a candidate may be preferentially left, for example, in the curve Cb in FIG.
次に、 これら候補の周波数 （周波数 1 , f 2 , f 3 ) に候補の順位を付ける。 順位は、 第 5図の周波数特性曲線 C cにおける振幅レベルが大きいものから高く 付けるようにする。 周波数 f 1 , ί 2 , f 3のうち、 第 5図の曲線 C cにおける振 幅レベルが最も大きいのは周波数 f 3であり、 その次に振幅レベルが大きいのは 周波数 f 2であり、 その次に振幅レベルが大きいのは周波数 f 1である。 よって、 この時点では、 周波数 f 3が第 1候補の周波数となり、 周波数 f 2が第 2候補の 周波数となり、 周波数 f 1が第 3候補の周波数となる。  Next, the candidate frequencies (frequency 1, f2, f3) are ranked. The order of the frequency characteristic curve Cc in FIG. Of the frequencies f 1, ί 2, and f 3, the frequency f 3 has the largest amplitude level in the curve C c in FIG. 5, and the frequency level f 2 has the next largest amplitude level. The next largest amplitude level is the frequency f1. Therefore, at this point, the frequency f3 is the frequency of the first candidate, the frequency f2 is the frequency of the second candidate, and the frequency f1 is the frequency of the third candidate.
次に、 第 2図のシステム Aが多数の周波数ポイントで測定した測定値から、 目 標振幅周波数特性を求める。 目標振幅周波数特性は、 第 2図のシステム Aが多数 の周波数ボイントで測定した測定値を周波数軸上で平滑化して得る。 平滑化の方 法としては、 例えば周波数軸上での移動平均を採用することができる。 先に、 第 4図の曲線 C a (基礎振幅周波数特性） は、 第 2図のシステム Aが多数の周波数 ポイントで測定した測定値を周波数軸上で平滑化したものであってもよいし、 平 滑化していないものであってもよいことを述べた。 基礎振幅周波数特性は、 平滑 化したものであっても平滑化したのものでなくてもよいが、 目標振幅周波数特性 は平滑化により求める。 目標振幅周波数特性は、 基礎振幅周波数特性よりも周波 数軸上での平滑度が大きくなるような平滑化により求める。 基礎振幅周波数特性 力 周波数軸上の例えば N cボイン卜の移動平均によって得たものであるとすれ ば (N cは所定の自然数)、 目標振幅周波数特性は、 N cポイントを超えるウィン ドウ幅 （例えば N fポイント（N f は N cを超える自然数）） の移動平均によって 得るようにすればよい。 このようにして目標振幅周波数特性は、 経験に頼ること なく、 客観的に得ることができる。 Next, the target amplitude frequency characteristic is obtained from the measured values measured at a number of frequency points by the system A in FIG. The target amplitude frequency characteristic is obtained by smoothing the measured values measured by the system A in FIG. 2 at a number of frequency points on the frequency axis. As the smoothing method, for example, a moving average on the frequency axis can be adopted. First, the curve C a (basic amplitude frequency characteristic) in FIG. 4 shows that the system A in FIG. He stated that the measured value measured at the point may be smoothed on the frequency axis, or may not be smoothed. The basic amplitude frequency characteristic may or may not be smoothed, but the target amplitude frequency characteristic is obtained by smoothing. The target amplitude frequency characteristic is obtained by smoothing such that the smoothness on the frequency axis is larger than the basic amplitude frequency characteristic. Fundamental amplitude frequency characteristic Force If it is obtained by, for example, moving average of Nc points on the frequency axis (Nc is a predetermined natural number), the target amplitude frequency characteristic is a window width exceeding Nc point ( For example, it may be obtained by a moving average of N f points (N f is a natural number exceeding N c). In this way, the target amplitude frequency characteristic can be obtained objectively without relying on experience.
第 7図の特性図では、 第 4図から曲線 C aを取り出して記載している。 第 7図 においては縦軸、 横軸とも対数軸であり、 縦軸は振幅レベルを横軸は周波数を示 す。 第 7図の曲線 C aは第 4図の曲線 C aと同一のものである。 第 7図の特性図 には、 破線による曲線 C dが記載されているが、 これ （曲線 C d ) は、 第 2図の システム Aで測定された多数の周波数ポイントでの振幅値を、 周波数軸上で移動 平均して得た曲線である。 このときの移動平均のためのウィンドウ幅は比較的大 きいので、 曲線 C d (目標振幅周波数特性） は曲線 C a (基礎振幅周波数特性） に比べてかなり平滑度が大きい。  In the characteristic diagram of FIG. 7, the curve Ca is extracted from FIG. 4 and described. In FIG. 7, both the vertical and horizontal axes are logarithmic axes, with the vertical axis representing amplitude level and the horizontal axis representing frequency. The curve C a in FIG. 7 is the same as the curve C a in FIG. The characteristic diagram in Fig. 7 shows a dashed curve C d (curve C d), which represents the amplitude values at a number of frequency points measured by system A in Fig. 2, It is a curve obtained by moving average on the axis. Since the window width for the moving average at this time is relatively large, the smoothness of the curve C d (target amplitude frequency characteristic) is considerably larger than that of the curve C a (basic amplitude frequency characteristic).
先に、 周波数 f 3を第 1候補の周波数として、 周波数 f 2を第 2候補の周波数 として、 周波数 f 1を第 3候補の周波数として選んだが、 次に、 これら候補の周 波数から、 目標振幅周波数特性 （曲線 C d ) の振幅レベルよりも基礎振幅周波数 特性 （曲線 C a ) の振幅レベルの方が小さいような周波数を候補から除外する。 第 7図から理解されるように、 周波数 f lにおいては、 目標振幅周波数特性 （曲 線 C d ) の振幅レベルよりも、 基礎振幅周波数特性 （曲線 C a ) の振幅レベルの 方が小さい。 よって、 周波数 f 1は候補の周波数から除外する。 その結果、 候補 の周波数は周波数 f 2と周波数 f 3のみとなる。 周波数 f 3が第 1候補の周波数 として、 周波数 f 2が第 2候補の周波数として残る。  Earlier, frequency f3 was selected as the first candidate frequency, frequency f2 was selected as the second candidate frequency, and frequency f1 was selected as the third candidate frequency.Next, from these candidate frequencies, the target amplitude was selected. Frequencies in which the amplitude level of the fundamental amplitude frequency characteristic (curve C a) is smaller than the amplitude level of the frequency characteristic (curve C d) are excluded from candidates. As can be understood from FIG. 7, at the frequency f l, the amplitude level of the basic amplitude frequency characteristic (curve C a) is smaller than the amplitude level of the target amplitude frequency characteristic (curve C d). Therefore, the frequency f1 is excluded from the candidate frequencies. As a result, the candidate frequencies are only the frequency f2 and the frequency f3. The frequency f3 remains as the first candidate frequency, and the frequency f2 remains as the second candidate frequency.
次に、 第 7図に基づき、 各候補の周波数が含まれる周波数範囲であって、 目標 振幅周波数特性の曲線 C dからの基礎振幅周波数特性の曲線 C aが周波数軸上で 1 c Next, based on FIG. 7, a curve C a of the basic amplitude frequency characteristic from the curve C d of the target amplitude frequency characteristic is a frequency range in which the frequency of each candidate is included on the frequency axis. 1 c
1 o 連続して正の方向にはみ出している周波数範囲を検出する。 第 1候補の周波数は 周波数 f 3であるが、 第 7図において、 周波数 f 3では目標振幅周波数特性より も基礎振幅周波数特性の振幅レベルの方が大きい。 第 7図の特性図の周波数軸上、 周波数 f 3の前後において、 基礎振幅周波数特性の曲線 C aと目標振幅周波数特 性の曲線 C dとが交差する点を検出すると、 周波数 ί 31と周波数 f 32とが検出さ れる。 周波数 ί 31および周波数 f 32において、 基礎振幅周波数特性の曲線 C aと 目標振幅周波数特性の曲線 C dとが交差している。 周波数 f 31は、 周波数 f 3よ りも低い周波数領域における基礎振幅周波数特性の曲線 C aと目標振幅周波数特 性の曲線 C dとの交差点のうちで、 周波数 f 3に最も近い周波数である。 また、 周波数 f 32は、 周波数： f 3よりも高い周波数領域における基礎振幅周波数特性の 曲線 C aと目標振幅周波数特性の曲線 C dとの交差点のうちで、 周波数 f 3に最 も近い周波数である。  1 o Detects the frequency range that continuously runs in the positive direction. Although the frequency of the first candidate is frequency f3, in FIG. 7, at frequency f3, the amplitude level of the basic amplitude frequency characteristic is higher than the target amplitude frequency characteristic. When a point where the curve C a of the basic amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic intersect on the frequency axis of the characteristic diagram of FIG. 7 around the frequency f 3 is detected, the frequency ί 31 and the frequency f 32 is detected. At frequency ί31 and frequency f32, the curve C a of the fundamental amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic intersect. The frequency f31 is the frequency closest to the frequency f3 among the intersections of the curve C a of the fundamental amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic in a frequency region lower than the frequency f 3. The frequency f32 is the frequency closest to the frequency f3 at the intersection between the curve C a of the basic amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic in a frequency region higher than the frequency f3. is there.
このようにして、 候補の周波数 f 3が含まれ、 かつ、 目標振幅周波数特性の曲 線 C dから基礎振幅周波数特性の曲線 C aが周波数軸上で連続して正の方向に （ 上方に） はみ出している周波数範囲 （周波数 f 31から周波数 32までの範囲） を検 出したら、 次に、 この周波数範囲に、 候補となる周波数が 2以上含まれていない か否かを調べる。 仮に、 2以上含まれている場合には、 その内の 1の周波数のみ を候補として残し、 他の周波数を候補から除外する。 いかなる周波数を候補とし て残すかは、 第 6図に示す特性 （第 2の振幅周波数特性 （曲線 C b ) ) の振幅レ ベルの大きさに基づいて決定する。 つまり、 第 2の振幅周波数特性 （曲線 C b ) の振幅レベルが最も大きな周波数のみを候補として残すのである。 第 7図におい て、 周波数 f 31から周波数: f 32までの周波数範囲には、 候補となる周波数は周波 数 f 3が含まれるのみであるから、 候補から除外される周波数はない。  In this way, the candidate frequency f 3 is included, and the curve C a of the fundamental amplitude frequency characteristic is continuously shifted from the curve C d of the target amplitude frequency characteristic in the positive direction (upward) on the frequency axis. After detecting the protruding frequency range (the range from frequency f31 to frequency 32), it is next checked whether this frequency range does not include two or more candidate frequencies. If two or more frequencies are included, only one of the frequencies is left as a candidate, and the other frequencies are excluded from the candidates. Which frequency is left as a candidate is determined based on the magnitude of the amplitude level of the characteristic (second amplitude frequency characteristic (curve Cb)) shown in FIG. In other words, only the frequency having the highest amplitude level of the second amplitude frequency characteristic (curve C b) is left as a candidate. In FIG. 7, in the frequency range from the frequency f31 to the frequency: f32, only the frequency f3 is included as a candidate frequency, and no frequency is excluded from the candidate.
同様のことを、 候補である周波数 f 2についても行う。 つまり、 周波数 f 2が 含まれる周波数範囲であって、 目標振幅周波数特性 （曲線 C d ) からの基礎振幅 周波数特性 （曲線 C a ) が周波数軸上で連続して正の方向にはみ出している周波 数範囲をまず検出する。 第 7図に示されるように、 周波数 f 21から周波数 f 22の 周波数範囲において、 目標振幅周波数特性 （曲線 C d ) からの基礎振幅周波数特 性 （曲線 C a ) が周波数軸上で連続して正の方向にはみ出している。 また、 この 周波数範囲には周波数 f 2が含まれる。 次に、 この周波数範囲に、 候補となる周 波数が 2以上含まれていないかを見ると、 この周波数範囲には周波数 ί 2以外に 候補となる周波数はない。 よって、 この周波数範囲には候補から除外される周波 数はない。 The same is performed for the candidate frequency f2. In other words, the frequency range in which the frequency f2 is included, the frequency where the fundamental amplitude frequency characteristic (curve C a) from the target amplitude frequency characteristic (curve C d) continuously protrudes in the positive direction on the frequency axis. A number range is first detected. As shown in Fig. 7, in the frequency range from frequency f21 to frequency f22, the fundamental amplitude frequency characteristic (curve C a) from the target amplitude frequency characteristic (curve C d) continuously appears on the frequency axis. It protrudes in the positive direction. Also, this The frequency range includes the frequency f2. Next, looking at whether this frequency range contains two or more candidate frequencies, there are no candidate frequencies other than frequency ί2 in this frequency range. Therefore, no frequencies are excluded from the candidate in this frequency range.
なお、 このような周波数範囲に候補となる周波数が複数存在する場合を、 第 8 図を参照して説明する。 第 8図の特性図における曲線 C eが基礎振幅周波数特性 を示す曲線であり、 曲線 C ίが目標振幅周波数特性を示す曲線であるとする。 両 曲線は周波数 f 61と周波数 f 62とで交差しており、 この周波数範囲 （周波数 ί 61 から周波数 f 62までの周波数範囲） に候補となる 3つの周波数 （周波数 f 51、 周 波数 f 52 および周波数 f 53) が存在するとする。  The case where there are a plurality of candidate frequencies in such a frequency range will be described with reference to FIG. It is assumed that a curve Ce in the characteristic diagram of FIG. 8 is a curve showing the basic amplitude frequency characteristic, and a curve Cί is a curve showing the target amplitude frequency characteristic. Both curves intersect at frequency f61 and frequency f62, and three frequencies (frequency f51, frequency f52 and frequency f52) that fall into this frequency range (frequency range from frequency ί61 to frequency f62) Suppose that a frequency f53) exists.
一方、 第 8図において、 曲線 C nは第 2の振幅周波数特性、 つまり、 共鳴空間 40において、 スピーカ 13から測定用信号 （正弦波スイープ信号） とマイクロホン 14の出力信号との合成信号を拡声させて、 マイクロホン Uによって受音して得ら れる振幅周波数特性である。 周波数 f 51、 周波数 f 52 および周波数： f 53の中で は、 第 2の振幅周波数特性 （曲線 C n ) の振幅レベルは、 周波数 f 51におけるも のが最も大きい。 よって、 周波数 f 51のみを候補の周波数として残し、 他の周波 数 （周波数 f 52と周波数 f 53) を候補から除外するのである。 これにより、 必要 以上の数の周波数が候補の周波数として残ることが防止される。 ひいては、 必要 以上の数のディップがディップフィル夕 4に設定されることが防止される。  On the other hand, in FIG. 8, the curve C n represents the second amplitude frequency characteristic, that is, the resonance signal 40 loudspeaks the composite signal of the measurement signal (sine wave sweep signal) and the output signal of the microphone 14 from the speaker 13. And amplitude frequency characteristics obtained by receiving sound with the microphone U. Among the frequencies f51, f52 and f53, the amplitude level of the second amplitude frequency characteristic (curve Cn) is the largest at the frequency f51. Therefore, only the frequency f51 is left as a candidate frequency, and the other frequencies (frequency f52 and frequency f53) are excluded from the candidates. This prevents more than necessary frequencies from remaining as candidate frequencies. As a result, it is possible to prevent more dips from being set in the dip fill 4 than necessary.
なお、 もしも候補の周波数 （周波数 f 51、 周波数 f 52、 周波数 f53) に、 基礎振幅 周波数特性 （曲線 C e ) と第 2の振幅周波数特性 （曲線 C n ) の振幅レベル差が 所定レベル以下 （例えば I d B以下） のものがあれば、 その周波数はディップフ ィル夕 4のディップの中心周波数として設定されないようにする。 よって、 周波数 f 5K 周波数 f 52 および周波数 ί 53の中では、 周波数 f51における第 2の振幅周 波数特性 （曲線 C n ) の振幅レベルが最も大きくても、 周波数 f51における基礎振 幅周波数特性 （曲線 C e ) と第 2の振幅周波数特性 （曲線 C n ) の振  If the candidate frequency (frequency f51, frequency f52, frequency f53) has a difference in amplitude level between the fundamental amplitude frequency characteristic (curve C e) and the second amplitude frequency characteristic (curve C n) below a predetermined level ( For example, if there is one that is less than I dB, the frequency should not be set as the center frequency of the dip in dip filter 4. Therefore, in the frequency f5K frequency f52 and the frequency ί53, even if the amplitude level of the second amplitude frequency characteristic (curve C n) at the frequency f51 is the largest, the fundamental amplitude frequency characteristic (curve C51) at the frequency f51 C e) and the amplitude of the second amplitude frequency characteristic (curve C n)
が所定レベル以下 （例えば l d B以下） であれば、 周波数 f 51を候補の周波数から 除外し、 第 2の振幅周波数特性 （曲線 C n ) の振幅レベルがその次に大きな周波 数 f 52を候補の周波数として残すようにする。 もちろん周波数 f 53は候補の周波数 から除外される。 Is less than a predetermined level (for example, less than ld B), the frequency f 51 is excluded from the candidate frequencies, and the frequency f 52 having the second highest amplitude level of the amplitude frequency characteristic (curve C n) is selected as the candidate. Frequency. Of course, frequency f 53 is the candidate frequency Excluded from
以上、 ある周波数範囲に候補となる 3つの周波数が存在する場合を、 第 8図を 参照して説明した。  As described above, the case where there are three candidate frequencies in a certain frequency range has been described with reference to FIG.
第 7図に基づき、 候補となる周波数が含まれる周波数範囲であって、 目標振幅 周波数特性 （曲線 Cd) から基礎振幅周波数特性 （曲線 Ca) が周波数軸上で連 続して正の方向にはみ出している周波数範囲をまず検出した。 そして、 検出され た各周波数範囲には、 候補となる周波数は 2以上は含まれておらず、 よって、 候 補の周波数 f 2と周波数 f 3は、 いずれも除外されずに候補として残ることを説 明した。  Based on Fig. 7, it is the frequency range that includes the candidate frequency, and the basic amplitude frequency characteristic (curve Ca) continuously protrudes in the positive direction from the target amplitude frequency characteristic (curve Cd) on the frequency axis. Frequency range is detected first. Then, in each of the detected frequency ranges, no more than two candidate frequencies are included, so that the candidate frequencies f 2 and f 3 remain as candidates without being excluded. explained.
次に、 このようにして残った周波数の候補に対して、 候補順位の付け替えを行 う。 付け替えは次のようにして行う。 つまり、 候補の周波数における基礎振幅周 波数特性 （曲線 Ca) と目標振幅周波数特性 （曲線 Cd) の振幅レベル差が大き いものほど高い順位となるように、 順位を付け替えるのである。 第 7図から理解 されるように、 周波数 ί 2における基礎振幅周波数特性 （曲線 Ca) と目標振幅 周波数特性 （曲線 Cd) の振幅レベル差は 2. 5 dBであり、 周波数 ί 3におけ る基礎振幅周波数特性 （曲線 Ca) と目標振幅周波数特性 （曲線 Cd) の振幅レ ベル差は 1. 8 dBである。 よって、 候補の順位が付け替えられ、 周波数 f 2が 第 1の候補となり、 周波数 f 3が第 2の候補となる。  Next, the remaining frequency candidates are rearranged in the candidate order. The replacement is performed as follows. In other words, the order is changed so that the higher the amplitude level difference between the basic amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) at the candidate frequency, the higher the rank. As can be understood from Fig. 7, the amplitude level difference between the fundamental amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) at frequency ί2 is 2.5 dB, and the fundamental amplitude frequency characteristic at frequency ί3 is The amplitude level difference between the amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) is 1.8 dB. Therefore, the order of the candidates is changed, and the frequency f2 becomes the first candidate, and the frequency f3 becomes the second candidate.
第 1の候補である周波数 f 2はディップフィルタ 4にディップの中心周波数 （除 去周波数） として設定されることが決定された。 次に、 この除去周波数 （周波数 f 2) におけるディップの減衰レベル （深さ） と尖鋭度 （Q) とを決定する手順 を説明する。  It has been determined that the frequency f2, which is the first candidate, is set in the dip filter 4 as the center frequency (removal frequency) of the dip. Next, the procedure for determining the dip attenuation level (depth) and the sharpness (Q) at the removal frequency (frequency f 2) will be described.
まず、 第 7図の特性図上で、 周波数 f 21から周波数 f 22までの周波数範囲にお いて基礎振幅周波数特性の曲線 C aと目標振幅周波数特性の曲線 C dとで囲まれ るエリア S 1の面積を検出する。 第 7図においてエリア S 1には斜線が施されて いるが、 検出されたエリア S 1の面積をここで T 1とする。  First, in the characteristic diagram of FIG. 7, in the frequency range from frequency f21 to frequency f22, an area S 1 surrounded by a curve C a of the basic amplitude frequency characteristic and a curve C d of the target amplitude frequency characteristic. The area of is detected. In FIG. 7, although the area S1 is hatched, the area of the detected area S1 is defined as T1 here.
次に、 周波数 f 2での目標振幅周波数特性 （曲線 Cd) と基礎振幅周波数特性 (曲線 Ca) の振幅レベル差の大きさを検出して、 この大きさ （差の大きさ） を ディップフィル夕 4のディップの減衰レベル （深さ） として想定する。 周波数 f 2 においては、 目標振幅周波数特性 （曲線 Cd) と基礎振幅周波数特性 （曲線 Ca ) の振幅レベル差は 2. 5 dBであるので、 ディップの深さはまず 2. 5 dBに 想定される。 Next, the magnitude of the amplitude level difference between the target amplitude frequency characteristic (curve Cd) and the fundamental amplitude frequency characteristic (curve Ca) at the frequency f2 is detected, and this magnitude (the magnitude of the difference) is dip-filled. Assume the attenuation level (depth) of the dip of 4. Frequency f 2 In, the difference in amplitude level between the target amplitude frequency characteristic (curve Cd) and the basic amplitude frequency characteristic (curve Ca) is 2.5 dB, so the dip depth is assumed to be 2.5 dB first.
次に、 ディップの尖鋭度 （Q) をまず 40と想定する。 そしてこの想定された ディップの深さと尖鋭度によって得られるディップの形状 （振幅周波数特性図上 でのディップの形状） からディップの面積を求める。  Next, the sharpness (Q) of the dip is first assumed to be 40. The dip area is determined from the dip shape (dip shape on the amplitude frequency characteristic diagram) obtained from the assumed dip depth and sharpness.
第 9図の特性図では、 中心周波数が周波数 f 2であるディップの振幅周波数特 性を曲線 Cgで表している。 第 9図においては縦軸、 横軸とも対数軸であり、 縦 軸は振幅レベルを横軸は周波数を示す。 この図において多数の平行する斜線が施 されたエリア S 2の面積が、 ここでいうディップの面積である。 ここで、 想定さ れたディップの深さと尖鋭度から求められるディップの面積を T 2とする。 そし て、 面積 T1と面積 T 2とを比較する。 面積 T 2が面積 T 1に等しいかそれ以上 である場合は、 そのときに想定されている減衰レベルと尖鋭度とをディップフィ ル夕 4の除去周波数におけるディップの減衰レベルおよび尖鋭度として一次決定す る。  In the characteristic diagram of FIG. 9, the amplitude frequency characteristic of the dip whose center frequency is the frequency f2 is represented by a curve Cg. In FIG. 9, both the vertical and horizontal axes are logarithmic axes, and the vertical axis shows the amplitude level and the horizontal axis shows the frequency. In this figure, the area of the area S2 with many parallel diagonal lines is the dip area here. Here, the area of the dip obtained from the assumed dip depth and sharpness is defined as T2. Then, the area T1 and the area T2 are compared. If the area T2 is equal to or greater than the area T1, the attenuation level and the sharpness assumed at that time are primarily determined as the dip attenuation level and the sharpness at the dip filter 4 removal frequency. You.
面積 T 2が面積 T 1よりも小さい場合は、 尖鋭度を 0. 1だけ小さくして改め て面積 T 2を求める。 そして再度、 面積 T1と面積 T 2とを比較する。 面積 T2 が面積 T 1に等しいかそれ以上である場合は、 そのときに想定されている減衰レ ベルと尖鋭度とをディップフィルタ 4の除去周波数におけるディップの減衰レベル および尖鋭度として一次決定するが、 面積 T 2が面積 T1よりも小さい場合は、 尖鋭度をさらに 0. 1だけ小さくして改めて面積 T 2を求め、 再度、 面積 T 1と 面積 T 2とを比較する。 以降同様に、 面積 T 2が面積 T1に等しいかそれ以上に なるまで、 尖鋭度を 0. 1づっ減少させてゆき、 面積 T 2が面積 T 1に等しいか それ以上になったときの減衰レベルと尖鋭度をディップフィルタ 4の除去周波数に おけるディップの減衰レベルおよび尖鋭度として一次決定する。  When the area T2 is smaller than the area T1, the sharpness is reduced by 0.1 and the area T2 is calculated again. Then, the area T1 and the area T2 are compared again. If the area T2 is equal to or larger than the area T1, the attenuation level and the sharpness assumed at that time are primarily determined as the dip attenuation level and the sharpness at the rejection frequency of the dip filter 4. If the area T 2 is smaller than the area T 1, the sharpness is further reduced by 0.1 to determine the area T 2 again, and the area T 1 and the area T 2 are compared again. Similarly, the sharpness is reduced by 0.1 until the area T2 is equal to or greater than the area T1, and the attenuation level when the area T2 is equal to or greater than the area T1. And the sharpness are primarily determined as the dip attenuation level and the sharpness at the removal frequency of the dip filter 4.
なお、 尖鋭度を所定値 （例えば 1. 5) まで減少させても面積 T 2が面積 T 1 よりも小さいままであれば、 以降は尖鋭度は減少させずに、 減衰レベルを所定値 づっ （例えば 0. 5 dBづっ） 増加させてゆく。 そして、 面積 T2が面積 T 1に 等しいかそれ以上になったときの減衰レベルと尖鋭度をディップフィル夕 4の除去 周波数におけるディップの減衰レベルおよび尖鋭度として一次決定する。 Note that if the area T2 remains smaller than the area T1 even if the sharpness is reduced to a predetermined value (for example, 1.5), then the sharpness is not reduced and the attenuation level is reduced to the predetermined value (for example, 1.5). For example, 0.5 dB). Then, when the area T2 becomes equal to or larger than the area T1, the attenuation level and the sharpness are removed by dip fill 4 It is primarily determined as the dip attenuation level and sharpness at the frequency.
さらに、 減衰レベルを所定値 （例えば 1 2 d B ) まで増加させても面積 T 2が 面積 T 1よりも小さいままであれば、 そのときの減衰レベルと尖鋭度をディップ フィル夕 4の除去周波数におけるディップの減衰レベルおよび尖鋭度として一次決 定する。  Furthermore, if the area T 2 remains smaller than the area T 1 even if the attenuation level is increased to a predetermined value (for example, 12 dB), the attenuation level and the sharpness at that time are reduced by the rejection frequency of the dip filter 4. Is determined primarily as the dip attenuation level and sharpness at.
このようにして、 第 1候補の周波数である周波数 f 2に基づき、 ディップフィ ル夕 4に設定すべき第 1番目の除去周波数 （ディップの中心周波数） とその周波数 におけるディップの減衰レベルと尖鋭度とを一次決定することができる。  Thus, based on the frequency f2, which is the first candidate frequency, the first rejection frequency (center frequency of the dip) to be set in the dip filter 4 and the attenuation level and sharpness of the dip at that frequency Can be primarily determined.
このようにしてディップの減衰レベルと尖鋭度とがー次決定されると、 次に、 ディップの減衰レベルや尖鋭度の二次決定が必要であるか否かを判断する。 この 二次決定の判断は次のようにして行う。 二次決定の具体的な方法は、 ディップの 中心周波数がいかなる周波数であるかによって異なる。  After the dip attenuation level and the sharpness are determined in this way, it is next determined whether or not the secondary determination of the dip attenuation level and the sharpness is necessary. The judgment of this secondary decision is made as follows. The specific method of the secondary determination depends on the center frequency of the dip.
まず、 ディップの減衰レベルの二次決定の具体的な方法を説明する。  First, a specific method of the secondary determination of the dip attenuation level will be described.
ディップの減衰レベルの二次決定は、 ディップの中心周波数が f g (H z )以下 である場合のみ行う。 そして、 ディップの中心周波数が f g (H z )以下であり、 かつ、 ディップの一次決定による減衰レベルが L h ( d B)未満である場合には、 ディップの減衰レベルを L h (d B)にするように二次決定を行う。 そして、 この 二次決定による減衰レベルが最終的にディップフィルタ 4に設定すべきディップの 減衰レベルとなる。  The quadratic determination of the dip attenuation level is performed only when the center frequency of the dip is less than f g (H z). If the center frequency of the dip is less than fg (H z) and the attenuation level determined by the primary determination of the dip is less than L h (d B), the attenuation level of the dip is set to L h (d B) Make a secondary decision to make Then, the attenuation level determined by this secondary determination finally becomes the attenuation level of the dip to be set in the dip filter 4.
ディップの中心周波数が f g (H z )以下であっても、 ディップの一次決定によ る減衰レベルが L h ( d B)以上である場合には、 一次決定された減衰レベルに対 して二次決定はなされず、 一次決定による減衰レベルが最終的にディップフィル タ 4に設定すべきディップの減衰レベルとなる。  Even if the center frequency of the dip is equal to or lower than fg (Hz), if the attenuation level determined by the primary determination of the dip is equal to or higher than Lh (dB), the attenuation level determined by the primary determination is two times. The next decision is not made, and the attenuation level determined by the primary decision finally becomes the dip attenuation level to be set in the dip filter 4.
また、 ディップの中心周波数が f g (H z )を超える場合には、 一次決定による 減衰レベルが L h (d B)未満であるか否かによらず、 一次決定された減衰レベル に対して二次決定はなされず、 一次決定による減衰レベルが最終的にディップフ ィル夕 4に設定すべきディップの減衰レベルとなる。  Also, when the center frequency of the dip exceeds fg (Hz), regardless of whether the attenuation level determined by the primary determination is less than Lh (dB), the attenuation level determined by the primary determination is The next decision is not made, and the attenuation level determined by the primary decision is the dip attenuation level to be finally set in dip field 4.
次に、 ディップの尖鋭度 （Q) の二次決定の具体的な方法を説明する。  Next, a specific method for the secondary determination of the dip sharpness (Q) will be described.
ディップの尖鋭度 （Q) の二次決定の方法は、 ディップの中心周波数によって 異なる。 The quadratic determination of dip sharpness (Q) depends on the center frequency of the dip different.
ディップの中心周波数が f i (Hz)未満であり（f iは： f gより小さな正数）、 かつ、 ディップの一次決定による尖鋭度が Jを超える場合には （Jは正数） 、 デ イッブの尖鋭度を jに変更するように二次決定を行う。 そして、 この二次決定に よる尖鋭度が最終的にディップフィル夕 4に設定すべきディップの尖鋭度となる。 ディップの中心周波数が f i (Hz)未満であっても、 ディップの一次決定によ る尖鋭度が J以下である場合には、 一次決定された尖鋭度に対して二次決定はな されず、 一次決定による尖鋭度が最終的にディップフィルタ 4に設定すべきディッ プの尖鋭度となる。  If the center frequency of the dip is less than fi (Hz) (fi is a positive number smaller than fg) and the sharpness determined by the primary determination of the dip exceeds J (J is a positive number), the sharpness of the dip Make a secondary decision to change the degree to j. Then, the sharpness determined by this secondary determination finally becomes the sharpness of the dip to be set in the dip fill 4. Even if the center frequency of the dip is less than fi (Hz), if the sharpness determined by the primary determination of the dip is J or less, no secondary determination is made for the primary determined sharpness, The sharpness determined by the primary determination finally becomes the sharpness of the dip to be set in the dip filter 4.
ディップの中心周波数が f i (Hz)以上 f g(Hz)以下であり、 かつ、 デイツ プの一次決定による尖鋭度が Kを超える場合には （Kは正数） 、 ディップの尖鋭 度を Kに変更するように二次決定を行う。 そして、 この二次決定による尖鋭度が 最終的にディップフィルタ 4に設定すべきディップの尖鋭度となる。  If the center frequency of the dip is not less than fi (Hz) and not more than fg (Hz), and the sharpness determined by the primary determination of the dip exceeds K (K is a positive number), change the sharpness of the dip to K Make a secondary decision to make Then, the sharpness determined by the secondary determination finally becomes the sharpness of the dip to be set in the dip filter 4.
ディップの中心周波数が ί i (Hz)以上 f g(Hz)以下であっても、 ディップ の一次決定による尖鋭度が K以下である場合には、 一次決定された尖鋭度に対し て二次決定はなされず、 一次決定による尖鋭度が最終的にディップフィルタ 4に設 定すべきディップの尖鋭度となる。  Even if the center frequency of the dip is not less than ίi (Hz) and not more than fg (Hz), if the sharpness determined by the primary determination of the dip is less than K, the secondary determination will not be performed on the primary determined sharpness. However, the sharpness determined by the primary determination is the sharpness of the dip to be finally set in the dip filter 4.
ディップの中心周波数が： f g (H z )を超え、 かつ、 ディップの一次決定による 尖鋭度が Lを超える場合には (Lは正数) 、 ディップの尖鋭度を Lに変更するよ うに二次決定を行う。 そして、 この二次決定による尖鋭度が最終的にディップフ ィルタ 4に設定すべきディップの尖鋭度となる。  If the center frequency of the dip exceeds: fg (H z) and the sharpness determined by the primary determination of the dip exceeds L (L is a positive number), the quadratic is changed to change the sharpness of the dip to L Make a decision. Then, the sharpness determined by the secondary determination finally becomes the sharpness of the dip to be set in the dip filter 4.
ディップの中心周波数が f g (Hz)を超えていても、 ディップの一次決定によ る尖鋭度が L以下である場合には、 一次決定された尖鋭度に対して二次決定はな されず、 一次決定による尖鋭度が最終的にディップフィルタ 4に設定すべきディッ プの尖鋭度となる。  Even if the center frequency of the dip exceeds fg (Hz), if the sharpness determined by the primary determination of the dip is equal to or less than L, no secondary determination is made for the primary determined sharpness, The sharpness determined by the primary determination finally becomes the sharpness of the dip to be set in the dip filter 4.
ここで仮に、 周波数 2が f i (Hz)以上 f g(Hz)以下の周波数であるとす る。 そして、 周波数 f 2を中心周波数とするディップの一次決定による減衰レべ ルが Lh(dB)未満であるとする。 そうすると、 ディップの減衰レベルは Lh(d B)に二次決定される。 このようにして最終的に決定されたディップの減衰レベル ^ が、 ディップフィルタ 4に設定すべきディップの特性となる。 Here, it is assumed that the frequency 2 is a frequency not less than fi (Hz) and not more than fg (Hz). Then, it is assumed that the attenuation level determined by the primary determination of the dip with the frequency f2 as the center frequency is less than Lh (dB). Then, the dip attenuation level is secondarily determined to Lh (d B). The dip attenuation level finally determined in this way ^ Is the dip characteristic to be set in the dip filter 4.
周波数 f 2についての減衰レベルが二次決定されたので、 次に、 この周波数 f 2についての尖鋭度の二次決定について判断する。 もしもこの周波数 ί 2におい て一次決定された尖鋭度が Κを超える場合には、 ディップの尖鋭度を Κに変更す るように二次決定を行う。 また、 もしも一次決定による尖鋭度が Κ以下である場 合には、 一次決定された尖鋭度に対して二次決定はなされない。  Since the attenuation level for the frequency f2 has been secondarily determined, next, the secondary determination of the sharpness for the frequency f2 is determined. If the sharpness determined primarily at this frequency ί2 exceeds Κ, a secondary decision is made to change the sharpness of the dip to Κ. If the sharpness determined by the primary determination is less than or equal to Κ, no secondary determination is made for the primary determined sharpness.
このように、 エリア S 1 (第 7図参照） とエリア S 2 (第 9図参照） との面積 が等しくなるようにして一次決定された減衰レベルに対して、 さらに二次決定を なすのは、 一次決定されたディップの減衰レベルをそのままディップフィルタ 4に 設定しても、 聴感上の変化が感じられない場合があるからである。 つまり、 一次 決定されたディップの減衰レベルが小さすぎる場合には、 この減衰レベルをその ままディップフィルタ 4に設定しても、 共鳴空間において共鳴が防止されていない と聴感上感ずることがあるのである。 このような事態を回避するために、 二次決 定において、 減衰レベルをさらに大きくするようにしたのである。 これにより、 共鳴空間において共鳴が防止されていると、 聴感上、 感ずることができるように なる。 つまり、 減衰レベルの二次決定は、 ディップフィルタ 4の効果を聴感上で有 効たらしめるための、 微調整の意味合いを持つ。  As described above, it is necessary to make a second-order decision with respect to the attenuation level determined so that the area of the area S 1 (see FIG. 7) is equal to the area of the area S 2 (see FIG. 9). This is because, even if the primary determined dip attenuation level is set in the dip filter 4 as it is, no change in the audibility may be felt. In other words, if the attenuation level of the primary determined dip is too low, even if this attenuation level is set to the dip filter 4 as it is, it may be perceived that resonance is not prevented in the resonance space. . In order to avoid such a situation, the attenuation was further increased in the secondary decision. As a result, if resonance is prevented in the resonance space, it becomes possible to feel the hearing. In other words, the secondary determination of the attenuation level has the meaning of fine adjustment in order to make the effect of the dip filter 4 effective on hearing.
なお、 減衰レベルの二次決定を施すディップを、 ί g (H z )以下の周波数のデ イッブに限ったのは、 拡声空間 40 (第 1図参照） においてスピーカ 13から放射さ れる音声の明瞭度が低下することを防止するためである。 つまり、 所定周波数 （ 例えば本実施形態では f g (H z )よりも高い周波数の成分は、 音声の明瞭度に対 する寄与が大きいため、 ディップの減衰レベルをあまり大きくしてしまうと、 音 声の明瞭度が低下する恐れがあるからである。  In addition, the dip for performing the secondary determination of the attenuation level is limited to those having a frequency equal to or lower than ίg (Hz) because the sound radiated from the speaker 13 in the loudspeaker space 40 (see FIG. 1) This is to prevent the degree from decreasing. In other words, the frequency component higher than the predetermined frequency (for example, higher than fg (Hz) in this embodiment) greatly contributes to the intelligibility of the voice. This is because clarity may be reduced.
また、 一次決定された尖鋭度に対して、 さらに二次決定をなすのは、 一次決定 されたディップの尖鋭度をそのままディップフィルタ 4に設定すると、 聴感上で違 和感が感じられる場合があるからである。 つまり、 尖鋭度が大きすぎるディップ 特性をディップフィルタ 4に設定すると、 聴感上で違和感を感ずることがあるので ある。 一般に、 尖鋭度が大きいほど、 ディップフィルタの周波数特性におけるデ ィップの中心周波数近傍での位相の変化が大きくなることが知られているが、 こ の、 周波数軸上における位相の急激な変化が、 聴感上の違和感を与えるのである。 従って、 一次決定されたディップの尖鋭度が大きすぎる場合、 つまりディップの 幅が狭すぎる場合には、 この尖鋭度をそのままディップフィルタ 4に設定すると、 音質を大きく損ない、 聴感上で違和感を感ずることがあるのである。 このような 事態を回避するために、 二次決定において、 ディップの幅を拡げるべく尖鋭度を さらに小さくするようにしたのである。 これにより、 ディップフィルタ 4の周波数 特性におけるディップの中心周波数近傍での位相の急激な変化が生ずることが回 避され、 共鳴空間において音質が大きく損なわれることはなくなり、 聴感上で違 和感を感ずることはなくなる。 つまり、 尖鋭度の二次決定は、 ディップフィルタ 4の特性の微調整の意味合いを持つ。 In addition, when making a secondary decision with respect to the primary determined sharpness, if the primary determined sharpness of the dip is set as it is in the dip filter 4, a sense of incongruity may be felt in the auditory sense Because. In other words, if a dip characteristic having too high a sharpness is set in the dip filter 4, a sense of incongruity may be felt in the sense of hearing. In general, it is known that the greater the sharpness, the greater the change in phase near the center frequency of the dip in the frequency characteristics of the dip filter. The sudden change in phase on the frequency axis gives a sense of incongruity. Therefore, if the sharpness of the first-determined dip is too large, that is, if the width of the dip is too narrow, setting this sharpness as it is in the dip filter 4 will greatly impair the sound quality and make the listener feel uncomfortable. There is. In order to avoid such a situation, in the secondary decision, the sharpness was further reduced in order to increase the dip width. This avoids a sudden change in the phase near the center frequency of the dip in the frequency characteristics of the dip filter 4, and does not significantly impair the sound quality in the resonance space, and gives a sense of discomfort to the listener. Will not be. In other words, the secondary determination of the sharpness has the meaning of fine adjustment of the characteristics of the dip filter 4.
次は、 第 2候補の周波数である周波数 f 3を、 ディップフィルタ 4に設定すべき 第 2番目の除去周波数 （ディップの中心周波数） として決定し、 その周波数にお けるディップの減衰レベルと尖鋭度とをまず一次決定する。  Next, the frequency f3, which is the second candidate frequency, is determined as the second removal frequency (center frequency of the dip) to be set in the dip filter 4, and the attenuation level and the sharpness of the dip at that frequency are determined. Is first determined.
ここで仮に、 周波数 f 3が f g (H z )よりも大きな周波数であるとする。 そう すると、 ディップの一次決定による減衰レベルが L h ( d B)未満であったとして も、 また、 L h ( d B)以上のレベルであったとしても、 一次決定された減衰レべ ルに対して二次決定はなされず、 一次決定による減衰レベルが最終的にディップ フィルタ 4に設定すべきディップの減衰レベルとなる。  Here, it is assumed that the frequency f 3 is higher than f g (H z). Then, even if the attenuation level determined by the primary determination of the dip is lower than L h (dB) or higher than L h (dB), the attenuation level determined by the primary determination is On the other hand, the secondary decision is not made, and the attenuation level by the primary decision finally becomes the dip attenuation level to be set in the dip filter 4.
次に、 この周波数 f 3についての尖鋭度の二次決定について判断する。 周波数 f 3は f g (H z )を超える周波数であるので、 もしもこの周波数 f 3において一 次決定された尖鋭度が Lを超える場合には、 ディップの尖鋭度を Lに変更するよ うに二次決定を行う。 また、 もしも一次決定による尖鋭度が L以下である場合に は、 一次決定された尖鋭度に対して二次決定はなされない。  Next, the secondary determination of the sharpness for the frequency f3 is determined. Since the frequency f 3 is higher than fg (H z), if the sharpness determined at this frequency f 3 exceeds L, the secondary is changed so that the sharpness of the dip is changed to L. Make a decision. If the sharpness determined by the primary determination is less than L, no secondary determination is made for the primary determined sharpness.
すでに周波数 f 1が候補の周波数からは除外されているので、 本実施形態では ディップフィル夕 4に設定すべき除去周波数 （ディップの中心周波数） は、 周波数 f 2と周波数 f 3のみである。  Since the frequency f1 has already been excluded from the candidate frequencies, in the present embodiment, only the frequency f2 and the frequency f3 are the removal frequencies (the center frequencies of the dips) to be set in the dipfiller 4.
このようにして、 ディップフィルタ 4に除去周波数として設定すべき周波数 f 2 ， f 3と、 その周波数におけるディップの減衰レベル （深さ） および尖鋭度 （Q) が決定される。 そしてこれらの特性を第 1図の音響システムにおけるディップフ ィルタ 4の特性として設定することにより、 拡声空間 40において共鳴が防止される c 上述の通り、 ディップフィルタ 4に設定されたディップの減衰レベルと尖鋭度と が、 一次決定された減衰レベルと尖鋭度のままであれば、 そのディップの面積は、 基礎振幅周波数特性が目標振幅周波数特性から上方にはみ出した面積と略一致し ており、 さらに原則として共鳴周波数 （ディップの中心周波数） における基礎振 幅周波数特性と目標振幅周波数特性の振幅レベル差がディップフィルタ 4のディッ プの減衰レベルとして設定されている。 よって、 基礎振幅周波数特性にディップ フィルタ 4の特性を作用させると、 目標振幅周波数特性に極めて近い特性となり、 かかる特性に設定されたディップフィルタ 4を含む第 1図の音響システムは、 音質 を損なうことなく共鳴を防止することができるような適切な特性に設定される。 また、 ディップフィルタ 4に設定されたディップの減衰レベルが、 二次決定され た減衰レベルであれば、 共鳴空間 40において共鳴が防止されていると、 聴感上、 感ずることができる。 また、 ディップフィル夕 4に設定されたディップの尖鋭度が、 二次決定された尖鋭度であれば、 共鳴空間 40において聴感上違和感のない音質が 得られる。 In this way, the frequencies f 2 and f 3 to be set as the removal frequencies in the dip filter 4 and the attenuation level (depth) and sharpness (Q) of the dip at that frequency are determined. Then, these characteristics are compared with the dip By setting the characteristics of the filter 4, as c above the resonance can be prevented in the loud sound space 40, and dip attenuation level set in the dip filter 4 and acuity, primary determined attenuation level and quality factor If it remains as it is, the area of the dip is approximately equal to the area where the fundamental amplitude frequency characteristic protrudes from the target amplitude frequency characteristic, and in principle, the fundamental amplitude frequency at the resonance frequency (center frequency of the dip) The amplitude level difference between the characteristic and the target amplitude frequency characteristic is set as the dip attenuation level of the dip filter 4. Therefore, when the characteristics of the dip filter 4 are applied to the basic amplitude frequency characteristics, the characteristics become very close to the target amplitude frequency characteristics, and the sound system of FIG. 1 including the dip filter 4 set to such characteristics impairs sound quality. It is set to an appropriate characteristic that can prevent resonance. In addition, if the attenuation level of the dip set in the dip filter 4 is a secondary-determined attenuation level, if resonance is prevented in the resonance space 40, the user can feel it audibly. Further, if the sharpness of the dip set in the dip fill 4 is the secondarily determined sharpness, sound quality that does not cause a sense of discomfort in the resonance space 40 can be obtained.
以上、 第 1〜9図を参照しつつ、 本願発明の一実施形態たるディップフィル夕 の周波数特性決定方法を説明した。  The method of determining the frequency characteristic of the dip filter according to an embodiment of the present invention has been described above with reference to FIGS.
上記実施形態では、 ディップの減衰レベルの二次決定は、 所定周波数 （f g (H z ) ) 以下の周波数に限って行うようにしたが、 かかる制限 （周波数の制限） を設 けないようにしてもよい。 つまり、 ディップの中心周波数が何 H zであろうと、 ディップの減衰レベルが所定レベル以下であれば減衰レベルをさらに大きくする ように二次決定を行うようにしてもよい。  In the above-described embodiment, the secondary determination of the dip attenuation level is performed only on the frequency equal to or lower than the predetermined frequency (fg (Hz)). However, such a restriction (frequency restriction) should not be set. Is also good. That is, no matter what the center frequency of the dip is, the secondary decision may be made to further increase the attenuation level if the attenuation level of the dip is equal to or lower than a predetermined level.
また上記実施形態では、 ディップの尖鋭度の二次決定において、 f i (H z )未 満の周波数では Jの尖鋭度を基準とし、 f i (H z )以上 f g (H z )以下の周波数 では、 Kの尖鋭度を基準とし、 f g (H z )を超える周波数では、 Lの尖鋭度を基 準とした。 つまり、 周波数に応じて異なる値の尖鋭度を基準として設けるように した。 しかし、 周波数によらず一定の値の尖鋭度を基準としてもよい。  Further, in the above embodiment, in the secondary determination of the dip sharpness, a frequency less than fi (Hz) is based on the sharpness of J, and a frequency less than fi (Hz) and fg (Hz) is less than fi (Hz). Based on the sharpness of K, at frequencies above fg (Hz), the sharpness of L was used as a reference. In other words, different values of sharpness are provided as a reference depending on the frequency. However, a fixed value of the sharpness may be used as a reference regardless of the frequency.
また、 上記実施形態では、 ディップフィル夕 4に設定すべき候補の周波数が比較 的少ない場合を示したが、 候補の周波数が多数ある場合は、 ディップフィル夕 4に 設定できるだけの数の除去周波数 （例えば 1 2個の除去周波数） と、 その周波数 における減衰レベル、 尖鋭度を、 同様の手順によって決定すればよい。 なお、 残 りの候補の周波数 （ディップフィルタ 4の除去周波数として決定された 1 2個以外 の候補の周波数） は、 ディップフィル夕 4に除去周波数として設定はされない。 上記説明から、 当業者にとっては、 本発明の多くの改良や他の実施形態が明ら かである。 従って、 上記説明は、 例示としてのみ解釈されるべきであり、 本発明 を実行する最良の態様を当業者に教示する目的で提供されたものである。 本発明 の精神を逸脱することなく、 その構造及び/又は機能の詳細を実質的に変更でき る。 In the above embodiment, the case where the number of candidate frequencies to be set for the dip-fill 4 is relatively small is shown. However, when there are many candidate frequencies, the dip-fill 4 The same procedure can be used to determine as many rejection frequencies as possible (for example, 12 rejection frequencies), and the attenuation level and sharpness at those frequencies. Note that the remaining candidate frequencies (the frequencies of the candidates other than the 12 candidates determined as the removal frequency of the dip filter 4) are not set as the removal frequencies in the dip filter 4. From the above description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the above description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.
[産業上の利用の可能性] [Possibility of industrial use]
本発明のディップフィルタの周波数特性決定方法によれば、 経験や熟練を必要 とせず、 ディップフィル夕の特性を適切に決定することができるので、 音響装置 の技術分野において有益である。  ADVANTAGE OF THE INVENTION According to the frequency characteristic determination method of the dip filter of the present invention, the characteristic of the dip filter can be appropriately determined without the need for experience or skill, which is useful in the technical field of audio equipment.

Claims

請 求 の 範 囲 The scope of the claims
1 . 共鳴空間で検出された共鳴周波数のうちの、 所定周波数以下 のものはディップの中心周波数から除外し、 該所定周波数を超えるもののみをデ ィップの中心周波数として決定し、 1. Of the resonance frequencies detected in the resonance space, those below a predetermined frequency are excluded from the center frequency of the dip, and only those above the predetermined frequency are determined as the center frequency of the dip.
該共鳴空間に配置されたスピーカから所定の測定用信号を拡声させ、 該共鳴空 間に配置されたマイクロホンによって受音して得られる測定値に基づき、 基礎振 幅周波数特性を求め、  A predetermined measurement signal is loudspeaked from a speaker arranged in the resonance space, and a fundamental amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space,
該測定値に基づき、 該基礎振幅周波数特性よりも周波数軸上での平滑度が大き い目標振幅周波数特性を求め、  Based on the measured value, a target amplitude frequency characteristic having a greater smoothness on the frequency axis than the basic amplitude frequency characteristic is obtained,
第 1面積に第 2面積が略一致するように該ディップの減衰レベル および尖鋭 度を一次決定し、  The attenuation level and sharpness of the dip are primarily determined so that the second area substantially matches the first area,
該第 1面積は、 振幅レベルを表す対数軸を縦軸とし周波数を表す軸を横軸とし た振幅周波数特性図上に該基礎振幅周波数特性の曲線と該目標振幅周波数特性の 曲線とを表したときの、 第 1周波数から第 2周波数までの周波数範囲において、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線とに囲まれるエリア の面積であり、  For the first area, the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are shown on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the ordinate and the axis representing the frequency as the abscissa. In the frequency range from the first frequency to the second frequency, the area of the area surrounded by the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic,
該第 1周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とが交差し、 かつ、 該ディップの中心周波数よりも低い周波数のうちの、 該ディ ップの中心周波数に最も近い周波数であり、  The first frequency is located at the center frequency of the dip among the frequencies at which the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect and are lower than the center frequency of the dip. Close frequency,
該第 2周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とが交差し、 かつ、 該ディップの中心周波数よりも高い周波数のうちの、 該ディ ップの中心周波数に最も近い周波数であり、  The second frequency intersects the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic, and has the highest frequency among the frequencies higher than the center frequency of the dip. Close frequency,
該第 2面積は、 振幅レベルを表す対数軸を縦軸とし周波数を表す軸を横軸とし た振幅周波数特性図上に該ディップの特性を表したときの、 該ディップの面積で ある、 ディップフィル夕の周波数特性決定方法。  The second area is an area of the dip when the characteristics of the dip are represented on an amplitude frequency characteristic diagram in which the logarithmic axis representing the amplitude level is the vertical axis and the axis representing the frequency is the horizontal axis. Evening frequency characteristic determination method.
2 . 該所定周波数が、 2 5 0 H z以下の周波数である、 請求項 1 記載のディップフィル夕の周波数特性決定方法。 2. The predetermined frequency is a frequency of 250 Hz or less. A method for determining the frequency characteristics of the described dip-fill.
3 . 共鳴空間で検出された共鳴周波数をディップの中心周波数と して決定し、 3. Determine the resonance frequency detected in the resonance space as the center frequency of the dip,
該共鳴空間に配置されたスピーカから所定の測定用信号を拡声させ、 該共鳴空 間に配置されたマイクロホンによって受音して得られる測定値に基づき、 基礎振 幅周波数特性を求め、  A predetermined measurement signal is loudspeaked from a speaker arranged in the resonance space, and a fundamental amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space,
該測定値に基づき、 該基礎振幅周波数特性よりも周波数軸上での平滑度が大き い目標振幅周波数特性を求め、  Based on the measured value, a target amplitude frequency characteristic having a greater smoothness on the frequency axis than the basic amplitude frequency characteristic is obtained,
第 1面積に第 2面積が略一致するように該ディップの減衰レベル および尖鋭 度を一次決定し、  The attenuation level and sharpness of the dip are primarily determined so that the second area substantially matches the first area,
該一次決定された該減衰レベルが所定レベル未満であるとき、 レベルをさらに 大きくするように該減衰レベルを二次決定し、  When the primary determined attenuation level is less than a predetermined level, the attenuation level is secondary determined so as to further increase the level;
該第 1面積は、 振幅レベルを表す対数軸を縦軸とし周波数を表す軸を横軸とし た振幅周波数特性図上に該基礎振幅周波数特性の曲線と該目標振幅周波数特性の 曲線とを表したときの、 第 1周波数から第 2周波数までの周波数範囲において、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線とに囲まれるエリア の面積であり、  For the first area, the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are shown on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the ordinate and the axis representing the frequency as the abscissa. In the frequency range from the first frequency to the second frequency, the area of the area surrounded by the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic,
該第 1周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とが交差し、 かつ、 該ディップの中心周波数よりも低い周波数のうちの、 該ディ ップの中心周波数に最も近い周波数であり、  The first frequency is located at the center frequency of the dip among the frequencies at which the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect and are lower than the center frequency of the dip. Close frequency,
該第 2周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とが交差し、 かつ、 該ディップの中心周波数よりも高い周波数のうちの、 該ディ ップの中心周波数に最も近い周波数であり、  The second frequency intersects the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic, and has the highest frequency among the frequencies higher than the center frequency of the dip. Close frequency,
該第 2面積は、 振幅レベルを表す対数軸を縦 とし周波数を表す軸を横軸とし た振幅周波数特性図上に該ディップの特性を表したときの、 該ディップの面積で ある、 ディップフィル夕の周波数特性決定方法。  The second area is the dip area when the characteristics of the dip are represented on an amplitude frequency characteristic diagram in which the logarithmic axis representing the amplitude level is vertical and the axis representing the frequency is the horizontal axis. Frequency characteristic determination method.
4 . 該一次決定された該減衰レベルが所定レベル未満であるとき、 該二次決定において、 該減衰レベルを該所定レベルにするように決定する、 請求 項 3記載のディップフィル夕の周波数特性決定方法。 4. When the primary determined attenuation level is less than a predetermined level, The method for determining a frequency characteristic of a dip filter according to claim 3, wherein in the secondary determination, the attenuation level is determined to be the predetermined level.
5 . 所定周波数以下の周波数を中心周波数とするディップにおい てのみ、 減衰レベルに対して二次決定を行う、 請求項 3又は 4記載のディップフ ィルタの周波数特性決定方法。 5. The method for determining a frequency characteristic of a dip filter according to claim 3, wherein a quadratic determination is performed on an attenuation level only in a dip having a frequency equal to or lower than a predetermined frequency as a center frequency.
6 . 共鳴空間で検出された共鳴周波数をディップの中心周波数と して決定し、 6. Determine the resonance frequency detected in the resonance space as the center frequency of the dip,
該共鳴空間に配置されたスピーカから所定の測定用信号を拡声させ、 該共鳴空 間に配置されたマイクロホンによって受音して得られる測定値に基づき、 基礎振 幅周波数特性を求め、  A predetermined measurement signal is loudspeaked from a speaker arranged in the resonance space, and a fundamental amplitude frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space,
該測定値に基づき、 該基礎振幅周波数特性よりも周波数軸上での平滑度が大き い目標振幅周波数特性を求め、  Based on the measured value, a target amplitude frequency characteristic having a greater smoothness on the frequency axis than the basic amplitude frequency characteristic is obtained,
第 1面積に第 2面積が略一致するように該ディップの減衰レベル および尖鋭 度を一次決定し、  The attenuation level and sharpness of the dip are primarily determined so that the second area substantially matches the first area,
該一次決定された該尖鋭度が所定値を超えるとき、 その値をさらに小さくする ように該尖鋭度を二次決定し、  When the primary determined sharpness exceeds a predetermined value, the sharpness is secondarily determined so as to further reduce the value,
該第 1面積は、 振幅レベルを表す対数軸を縦軸とし周波数を表す軸を横軸とし た振幅周波数特性図上に該基礎振幅周波数特性の曲線と該目標振幅周波数特性の 曲線とを表したときの、 第 1周波数から第 2周波数までの周波数範囲において、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線とに囲まれるエリア の面積であり、  For the first area, the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are shown on an amplitude frequency characteristic diagram with the logarithmic axis representing the amplitude level as the ordinate and the axis representing the frequency as the abscissa. In the frequency range from the first frequency to the second frequency, the area of the area surrounded by the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic,
該第 1周波数は、 該基礎振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とが交差し、 かつ、 該ディップの中心周波数よりも低い周波数のうちの、 該ディ ップの中心周波数に最も近い周波数であり、  The first frequency is located at the center frequency of the dip among the frequencies at which the curve of the fundamental amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect and are lower than the center frequency of the dip. Close frequency,
該第 2周波数は、 該基^振幅周波数特性の曲線と該目標振幅周波数特性の曲線 とが交差し、 かつ、 該ディップの中心周波数よりも高い周波数のうちの、 該ディ ップの中心周波数に最も近い周波数であり、 該第 2面積は、 振幅レベルを表す対数軸を縦軸とし周波数を表す軸を横軸とし た振幅周波数特性図上に該ディップの特性を表したときの、 該ディップの面積で ある、 ディップフィル夕の周波数特性決定方法。 The second frequency is defined as the center frequency of the dip among the frequencies at which the curve of the base amplitude frequency characteristic and the curve of the target amplitude frequency characteristic intersect and which are higher than the center frequency of the dip. The closest frequency, The second area is an area of the dip when the characteristics of the dip are represented on an amplitude frequency characteristic diagram in which the logarithmic axis representing the amplitude level is the vertical axis and the axis representing the frequency is the horizontal axis. Evening frequency characteristic determination method.
7 . 該一次決定された該尖鋭度が所定値を超えるとき、 該二次決 定において該尖鋭度を該所定値にする、 請求項 6記載のディップフィル夕の周波 数特性決定方法。 7. The method according to claim 6, wherein the sharpness is set to the predetermined value in the secondary determination when the primary sharpness exceeds a predetermined value.
8 . 該目標振幅周波数特性は、 測定された振幅周波数特性を周波 数軸上で移動平均することによって平滑化された特性である、 請求項 1乃至 7の いずれか一の項に記載のディップフィル夕の周波数特性決定方法。 8. The dip filter according to any one of claims 1 to 7, wherein the target amplitude frequency characteristic is a characteristic smoothed by moving-averaging the measured amplitude frequency characteristic on a frequency axis. Evening frequency characteristic determination method.
9 . 該一次決定において、 該ディップの減衰レベルを、 該デイツ プの中心周波数における該基礎振幅周波数特性と該目標振幅周波数特性の振幅レ ベル差に略一致するように決定し、 該ディップの尖鋭度を、 該第 1面積に該第 2 面積が略一致するように決定する、 請求項 1乃至 8のいずれか一の項に記載のデ イツプフィルタの周波数特性決定方法。 9. In the primary determination, the attenuation level of the dip is determined so as to substantially match the amplitude level difference between the basic amplitude frequency characteristic and the target amplitude frequency characteristic at the center frequency of the dip, and the sharpness of the dip is determined. 9. The frequency characteristic determination method for a depth filter according to claim 1, wherein the degree is determined such that the second area substantially matches the first area.
1 0 . 該第 1周波数から該第 2周波数までの周波数範囲に、 該共 鳴空間で検出された複数の共鳴周波数が含まれるとき、 該複数の共鳴周波数の内 の、 第 2の振幅周波数特性の振幅レベルが最も大きな共鳴周波数を、 該ディップ の中心周波数として決定し、 それ以外の共鳴周波数を該ディップの中心周波数と はしないように決定し、 10. When a plurality of resonance frequencies detected in the resonance space are included in the frequency range from the first frequency to the second frequency, a second amplitude frequency characteristic of the plurality of resonance frequencies is included. The resonance frequency having the highest amplitude level is determined as the center frequency of the dip, and the other resonance frequencies are determined not to be the center frequency of the dip.
該第 2の振幅周波数特性は、 該スピー力から該測定用信号と該マイクロホンの 出力信号との合成信号を拡声させて、 該マイクロホンによって受音して得られる 振幅周波数特性である、 請求項 1乃至 9のいずれか一の項に記載のディップフィ ルタの周波数特性決定方法。  2. The second amplitude frequency characteristic is an amplitude frequency characteristic obtained by loudspeaking a synthesized signal of the measurement signal and the output signal of the microphone from the speed, and receiving the sound by the microphone. 10. The method for determining a frequency characteristic of a dip filter according to any one of Items 9 to 9.
1 1 . 第 1の振幅周波数特性と第 2の振幅周波数特性との比較に 基づいて、 該共鳴空間の共鳴周波数を検出し、 1 1. For comparison between the first amplitude frequency characteristic and the second amplitude frequency characteristic Detecting a resonance frequency of the resonance space,
該第 1の振幅周波数特性は、 該測定値に基づいて得られる振幅周波数特性であ Ό ,  The first amplitude frequency characteristic is an amplitude frequency characteristic obtained based on the measurement value.
該第 2の振幅周波数特性は、 該スピー力から該測定用信号と該マイクロホンの 出力信号との合成信号を拡声させて、 該マイクロホンによって受音して得られる 振幅周波数特性である、 請求項 1乃至 1 0のいずれか一の項に記載のディップフ ィルタの周波数特性決定方法。  2. The second amplitude frequency characteristic is an amplitude frequency characteristic obtained by loudspeaking a synthesized signal of the measurement signal and the output signal of the microphone from the speed, and receiving the sound by the microphone. 13. The method for determining a frequency characteristic of a dip filter according to any one of the above items.
1 2 . 該第 1の振幅周波数特性と該第 2の振幅周波数特性との差 分から、 該第 1の振幅周波数特性に比べて該第 2の振幅周波数特性の方が振幅が 大きいピーク点の周波数を該共鳴空間の共鳴周波数として検出する、 請求項 1 1 記載のディップフィル夕の周波数特性決定方法。 1 2. From the difference between the first amplitude frequency characteristic and the second amplitude frequency characteristic, the frequency at the peak point where the second amplitude frequency characteristic has a larger amplitude than the first amplitude frequency characteristic 12. The method of determining a frequency characteristic of a dip filter according to claim 11, wherein the frequency is detected as a resonance frequency of the resonance space.
1 3 . 該測定用信号が正弦波スイープ信号である、 請求項 1乃至13. The signal for measurement is a sine wave sweep signal.
1 2のいずれか一の項に記載のディップフィルタの周波数特性決定方法。 13. The method for determining a frequency characteristic of a dip filter according to any one of the items 12.
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