EP0240798A1 - Hearing aid noise suppression system - Google Patents
Hearing aid noise suppression system Download PDFInfo
- Publication number
- EP0240798A1 EP0240798A1 EP87104004A EP87104004A EP0240798A1 EP 0240798 A1 EP0240798 A1 EP 0240798A1 EP 87104004 A EP87104004 A EP 87104004A EP 87104004 A EP87104004 A EP 87104004A EP 0240798 A1 EP0240798 A1 EP 0240798A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hearing aid
- circuit
- capacitor
- filter
- attack
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
- 230000001629 suppression Effects 0.000 title description 2
- 239000003990 capacitor Substances 0.000 claims description 32
- 230000003247 decreasing effect Effects 0.000 claims description 2
- 230000006870 function Effects 0.000 claims description 2
- 230000003321 amplification Effects 0.000 claims 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims 3
- 238000007599 discharging Methods 0.000 claims 2
- 230000000694 effects Effects 0.000 abstract description 6
- 230000007423 decrease Effects 0.000 description 8
- 230000010354 integration Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
- H04R25/502—Customised settings for obtaining desired overall acoustical characteristics using analog signal processing
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/32—Automatic control in amplifiers having semiconductor devices the control being dependent upon ambient noise level or sound level
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G5/00—Tone control or bandwidth control in amplifiers
- H03G5/16—Automatic control
- H03G5/18—Automatic control in untuned amplifiers
Definitions
- the invention relates to hearing aids, and more particularly relates to hearing aids of the type which respond to changes of noise levels in the user's sound environment.
- a hearing aid improves when its frequency response changes with the ambient noise level. This can be done, for example, by monitoring the sound environment for the presence of low-frequency sounds, which are present in noisy environments. In devices of this type, the frequency response of the hearing aid is changed so that the device becomes less responsive to low-frequency sounds as those sounds become louder, and vice versa. This blocks out the noise and improves intelligibility for the user.
- One object of the invention is to provide a hearing aid which has a variable frequency response to improve intelligibility in high noise environments which is nonetheless comfortable for use.
- Another object is, in general, to improve on known devices of this type.
- the frequency response of the hearing aid is varied in accordance with the presence and absence of low-frequency sounds in the user's sonic environment. Further in accordance with the invention, the hearing aid responds more quickly to increases in noise level and much more slowly to decreases in noise level. This gives a user's auditory system time to adapt to the changed frequency response of the hearing aid while still preserving intelligibility in the presence of high noise levels.
- the hearing aid has a filter capacitor through which the signal from the microphone passes before entering the amplifier.
- the filter capacitor is shunted by a resistive path of variable resistance; this path is preferably the collector-emitter path of a transistor whose conductive state is determined by the presence of low-frequency sounds present at the microphone.
- the base of the transistor is connected to a charging capacitor which charges more quickly with increased noise levels and which discharges only much more slowly when the noise levels decrease. This gives the system the desired faster attack time (to increase intelligibility in the presence of noise) and much slower release time (to give the user's auditory system the opportunity to adapt and therefore to increase comfort) when the noise level diminishes.
- a hearing aid contains a microphone 2, a power amplifier 4, and a receiver 6 which functions as a loudspeaker. Between the microphone 2 and the power amplifier 4 is an adjustable high-pass filter 8 made up of two series-connected capacitors 10 and 12.
- the frequency response of this system is determined by the characteristics of the filter 8. As will be explained below, the impedance of this filter 8, and therefore the frequency response of the whole system, is varied by shunting across the capacitor 12 with a variable resistance determined by the presence of noise at the microphone 2. The mechanics by which such variation is accomplished will now be discussed.
- a circuit 14 is used to carry this variation out.
- an active low frequency bandpass filter 16 which identifies noise (here, low-frequency sounds from 500 Hz down to 150 Hz) at the microphone 2.
- the bandpass filter 16 in this example is made up of an operational amplifier 16A whose output and inverting input are bridged by a parallel RC network which includes capacitor 16B and resistor 16C.
- the input of the operational amplifier 16A, and therefore of the bandpass filter 16 is connected to the microphone 2 through a series circuit which includes a potentiometer 18, a capacitor 20, and a resistor 22.
- the potentiometer 18 is used to set the level of the circuit 14.
- Audio sounds within the frequency band passed by the bandpass filter 16 are then routed to the input of an operational amplifier 28 through a series RC circuit which includes a resistor 24 and capacitor 26.
- the operational amplifier 28 is connected as a conventional driver amplifier with a resistance 30 between its output and inverting intput.
- the operational amplifier 28 appropriately biases the base-emitter circuit of an NPN transistor 32, whose collector is connected to the voltage source.
- the transistor 32 is biased in such a way that it rectifies the signal at the output of the operational amplifier 28. (Rectification is necessary so as not to discharge the capacitor 36 described below).
- the circuit 14 responds to low-frequency noise at the microphone 2 by keeping the high-pass filter 8 in its highest-pass state. This is because a large quantity of noise at the microphone 2 will tend to keep the capacitor 36 charged up, rendering the transistor 34 entirely non-conductive and placing an open resistive circuit across the capacitor 12.
- the current flow through the transistor 32 decreases, the charge across the capacitor 36 decreases, the transistor 34 becomes more conductive, and the effect of the capacitor 12 becomes less and less important to the high-pass filter 8.
- the frequency response of the system is adapted to the noise in the user's environment; the system becomes less responsive to low frequencies as the low frequencies become more predominant.
- the resistance of resistor 38 is much less than the resistance of the resistor 42. This has the effect that increased noise levels at the microphone 2 cause the capacitor 36 to charge up more rapidly than it can discharge when the noise level at the microphone 2 decreases.
- the effect of this electrical characteristic is that when noise at the microphone 2 rises, the system soon becomes less responsive to noise so that intelligibility is maintained.
- the ambient noise level drops, the increased low-frequency response of the system is phased in over a much longer period of time, to permit the user's hearing system to adjust.
- This type of response is known to persons skilled in the art as a faster attack time and a much slower release time.
- the attack time is approximately ten times as long as the release time. It should be noted that the attack time, while fast in comparison to the release time, is not fast in the absolute sense. This is so that the hearing aid does not respond to short, momentary noise lasting less than perhaps 50 ms.
- Fig. 2 The response of the bandpass filter 16 in this example is illustrated in Fig. 2. This indicates that "noise” is defined as sounds having frequencies in the band between 500 Hz and 150 Hz. While this particular response is desired, it is not necessary for the practice of the invention and the width, shape and actual location of the band which is passed by the bandpass filter 16 can be changed.
- Fig. 3 illustrates the response of the invention to changes in the amount of 250 Hz noise at the input of the circuit 14.
- the quantity of noise is abruptly reduced. This shows that the gain of the system is cut down but then slowly rises once again until the high-pass filter 8 has reached its least high-pass state.
- the attack time constant of approximately 70 msec gives the circuit the same loundness integration behavior as the human auditory system.
- the ear has a temporal integration time constant in the range of 50 to 100 msec.
- Fig. 4 shows the overall response of the invention to a 250 Hz signal. This indicates that the response of the system begins to drop at approximately 40db below lV and only begins rising at about 47db. This curve can be shifted up and down by adjusting the potentiometer 18.
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- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Neurosurgery (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Control Of Amplification And Gain Control (AREA)
- Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
Abstract
A hearing aid responds to increased noise by changing its frequency response to reduce the effects of the noise. The hearing aid has a fast attack time and a much slower release time.
Description
- The invention relates to hearing aids, and more particularly relates to hearing aids of the type which respond to changes of noise levels in the user's sound environment.
- It is known that the performance of a hearing aid improves when its frequency response changes with the ambient noise level. This can be done, for example, by monitoring the sound environment for the presence of low-frequency sounds, which are present in noisy environments. In devices of this type, the frequency response of the hearing aid is changed so that the device becomes less responsive to low-frequency sounds as those sounds become louder, and vice versa. This blocks out the noise and improves intelligibility for the user.
- However, these known devices are difficult to use. This is because known hearing aids respond to short-duration sounds, thereby causing uncomfortable rapid fluctuations of the signal level when the noise level changes.
- It would be advantageous to provide a hearing aid which provided a noise suppression feature that was nonetheless comfortable for a user.
- One object of the invention is to provide a hearing aid which has a variable frequency response to improve intelligibility in high noise environments which is nonetheless comfortable for use.
- Another object is, in general, to improve on known devices of this type.
- In accordance with the invention, the frequency response of the hearing aid is varied in accordance with the presence and absence of low-frequency sounds in the user's sonic environment. Further in accordance with the invention, the hearing aid responds more quickly to increases in noise level and much more slowly to decreases in noise level. This gives a user's auditory system time to adapt to the changed frequency response of the hearing aid while still preserving intelligibility in the presence of high noise levels.
- In a preferred embodiment, the hearing aid has a filter capacitor through which the signal from the microphone passes before entering the amplifier. The filter capacitor is shunted by a resistive path of variable resistance; this path is preferably the collector-emitter path of a transistor whose conductive state is determined by the presence of low-frequency sounds present at the microphone. Further advantageously, the base of the transistor is connected to a charging capacitor which charges more quickly with increased noise levels and which discharges only much more slowly when the noise levels decrease. This gives the system the desired faster attack time (to increase intelligibility in the presence of noise) and much slower release time (to give the user's auditory system the opportunity to adapt and therefore to increase comfort) when the noise level diminishes.
- Exemplary and non-limiting preferred embodiments of the invention are shown in the drawings, in which:
- Fig. 1 is a diagram of an in-the-ear hearing aid in accordance with the invention;
- Fig. 2 illustrates the response of a typical bandpass filter in the preferred embodiment;
- Fig. 3 illustrates a typical faster attack time and slower release time in accordance with the invention; and
- Fig. 4 illustrates a typical response of the invention to increased noise levels.
- A hearing aid contains a
microphone 2, a power amplifier 4, and areceiver 6 which functions as a loudspeaker. Between themicrophone 2 and the power amplifier 4 is an adjustable high-pass filter 8 made up of two series-connectedcapacitors - The frequency response of this system is determined by the characteristics of the filter 8. As will be explained below, the impedance of this filter 8, and therefore the frequency response of the whole system, is varied by shunting across the
capacitor 12 with a variable resistance determined by the presence of noise at themicrophone 2. The mechanics by which such variation is accomplished will now be discussed. - A circuit 14 is used to carry this variation out. Within the circuit 14, there is contained an active low
frequency bandpass filter 16, which identifies noise (here, low-frequency sounds from 500 Hz down to 150 Hz) at themicrophone 2. Thebandpass filter 16 in this example is made up of an operational amplifier 16A whose output and inverting input are bridged by a parallel RC network which includes capacitor 16B andresistor 16C. The input of the operational amplifier 16A, and therefore of thebandpass filter 16, is connected to themicrophone 2 through a series circuit which includes apotentiometer 18, acapacitor 20, and aresistor 22. Thepotentiometer 18 is used to set the level of the circuit 14. - Sounds within the frequency band passed by the
bandpass filter 16 are then routed to the input of anoperational amplifier 28 through a series RC circuit which includes aresistor 24 andcapacitor 26. Theoperational amplifier 28 is connected as a conventional driver amplifier with aresistance 30 between its output and inverting intput. - The
operational amplifier 28 appropriately biases the base-emitter circuit of anNPN transistor 32, whose collector is connected to the voltage source. Thetransistor 32 is biased in such a way that it rectifies the signal at the output of theoperational amplifier 28. (Rectification is necessary so as not to discharge thecapacitor 36 described below). - Current passing through the emitter of
transistor 32 is used to control the conductive state of aPNP transistor 34 which has its collector-emitter circuit connected across thecapacitor 12. This is done indirectly by using the current through the emitter of thetransistor 32 to charge up acapacitor 36 and by making the conductive state oftransistor 34 dependant upon the voltage across thecapacitor 36. - Current passing through the emitter of the
transistor 32 passes through aresistor 38, which is connected to one plate of thecapacitor 36. The other plate of thecapacitor 36 is grounded. The ungrounded plate ofcapacitor 36 is connected to the base oftransistor 34 through aresistor 40 and aresistor 42 shunts across thecapacitor 36. - When current flows through the emitter of
transistor 32, the current passes throughresistor 38 and chargescapacitor 36. As the voltage acrosscapacitor 36 increases, the voltage difference between the base and the emitter oftransistor 34 also decreases, making thetransistor 34 less conductive. This has the effect of shunting thecapacitor 12 with a resistor of increasing resistance. - When current flow through the emitter of
transistor 32 decreases, thecapacitor 36 then discharges through theresistor 42. This reduces the voltage across thecapacitor 36, reduces the voltage at the base oftransistor 34, increases the voltage across the emitter-base junction oftransistor 34, and makestransistor 34 more conductive. This has the effect of placing a resistive shunt of decreasing resistance acrosscapacitor 12. - Thus, the circuit 14 responds to low-frequency noise at the
microphone 2 by keeping the high-pass filter 8 in its highest-pass state. This is because a large quantity of noise at themicrophone 2 will tend to keep thecapacitor 36 charged up, rendering thetransistor 34 entirely non-conductive and placing an open resistive circuit across thecapacitor 12. However, as the noise atmicrophone 2 decreases, the current flow through thetransistor 32 decreases, the charge across thecapacitor 36 decreases, thetransistor 34 becomes more conductive, and the effect of thecapacitor 12 becomes less and less important to the high-pass filter 8. In this way, the frequency response of the system is adapted to the noise in the user's environment; the system becomes less responsive to low frequencies as the low frequencies become more predominant. - The resistance of
resistor 38 is much less than the resistance of theresistor 42. This has the effect that increased noise levels at themicrophone 2 cause thecapacitor 36 to charge up more rapidly than it can discharge when the noise level at themicrophone 2 decreases. The effect of this electrical characteristic is that when noise at themicrophone 2 rises, the system soon becomes less responsive to noise so that intelligibility is maintained. However, when the ambient noise level drops, the increased low-frequency response of the system is phased in over a much longer period of time, to permit the user's hearing system to adjust. This type of response is known to persons skilled in the art as a faster attack time and a much slower release time. In this example, the attack time is approximately ten times as long as the release time. It should be noted that the attack time, while fast in comparison to the release time, is not fast in the absolute sense. This is so that the hearing aid does not respond to short, momentary noise lasting less than perhaps 50 ms. - The response of the
bandpass filter 16 in this example is illustrated in Fig. 2. This indicates that "noise" is defined as sounds having frequencies in the band between 500 Hz and 150 Hz. While this particular response is desired, it is not necessary for the practice of the invention and the width, shape and actual location of the band which is passed by thebandpass filter 16 can be changed. - Fig. 3 illustrates the response of the invention to changes in the amount of 250 Hz noise at the input of the circuit 14. At time t₁, the quantity of noise is abruptly reduced. This shows that the gain of the system is cut down but then slowly rises once again until the high-pass filter 8 has reached its least high-pass state. When, at time t₂, the amount of noise is abruptly increased, the system responds with a faster attack time to put a rapid clamp on the response of the circuit to the noise by shifting the frequency response of the high-pass filter upward. The attack time constant of approximately 70 msec gives the circuit the same loundness integration behavior as the human auditory system. The ear has a temporal integration time constant in the range of 50 to 100 msec.
- Fig. 4 shows the overall response of the invention to a 250 Hz signal. This indicates that the response of the system begins to drop at approximately 40db below lV and only begins rising at about 47db. This curve can be shifted up and down by adjusting the
potentiometer 18. - Those skilled in the art will understand that changes can be made in the preferred embodiments here described, and that these embodiments can be used for other purposes. Such changes and uses are within the scope of the invention, which is limited only by the claims which follow.
Claims (4)
1. A hearing aid, comprising:
a microphone (2);
an amplification system (4) amplifying signals produced by the microphone;
a receiver (6) for converting signals amplified by the amplification system into acoustic information; and
means (8, 14) for varying the frequency response of the amplification system as a function of the existence of low-frequency sounds at said microphone, said varying means having a fast attack time and a much slower release time.
a microphone (2);
an amplification system (4) amplifying signals produced by the microphone;
a receiver (6) for converting signals amplified by the amplification system into acoustic information; and
means (8, 14) for varying the frequency response of the amplification system as a function of the existence of low-frequency sounds at said microphone, said varying means having a fast attack time and a much slower release time.
2. A hearing aid circuit, comprising:
a high-pass filter (8) with adjustable frequency response;
a bandpass filter (16); and
an attack and release circuit (24 through 42) connecting the bandpass filter (16) to the high-pass filter (8) in a manner that an increased output from the bandpass filter changes the frequency response of the high-pass filter after an attack time and a decreased output from the bandpass filter changes the frequency response of the high-pass filter after a release time which is much longer than said attack time.
a high-pass filter (8) with adjustable frequency response;
a bandpass filter (16); and
an attack and release circuit (24 through 42) connecting the bandpass filter (16) to the high-pass filter (8) in a manner that an increased output from the bandpass filter changes the frequency response of the high-pass filter after an attack time and a decreased output from the bandpass filter changes the frequency response of the high-pass filter after a release time which is much longer than said attack time.
3. The hearing aid circuit of claim 2, wherein said high-pass filter (8) comprises a filter capacitor (12) and said attack and release circuit (24 through 42) comprises a transistor (34) with its collector-emitter circuit shunting said filter capacitor.
4. The hearing aid circuit of claim 3, wherein said attack and release circuit (14) further comprises a timing capacitor (36) which is connected to the base of said transistor (34), a charging resistor (38) through which said timing capacitor is clamped, and a discharging resistor (42) thereof which said timing capacitor is discharged, said charging resistor (38) having a lower resistance than said discharging resistor (42).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/846,662 US4750207A (en) | 1986-03-31 | 1986-03-31 | Hearing aid noise suppression system |
US846662 | 1986-03-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0240798A1 true EP0240798A1 (en) | 1987-10-14 |
Family
ID=25298583
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87104004A Withdrawn EP0240798A1 (en) | 1986-03-31 | 1987-03-18 | Hearing aid noise suppression system |
Country Status (5)
Country | Link |
---|---|
US (1) | US4750207A (en) |
EP (1) | EP0240798A1 (en) |
JP (1) | JPS62242500A (en) |
CA (1) | CA1273097A (en) |
DK (1) | DK150587A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2635680A1 (en) * | 1988-08-30 | 1990-03-02 | Belone Electronics Corp | HEARING AID |
US5170434A (en) * | 1988-08-30 | 1992-12-08 | Beltone Electronics Corporation | Hearing aid with improved noise discrimination |
AU637722B2 (en) * | 1990-10-30 | 1993-06-03 | Ascom Audiosys Ag | A method of supressing noise in hearing aids |
EP0635937A1 (en) * | 1993-07-22 | 1995-01-25 | Eastman Kodak Company | Circuit for controlling the overall upper cutoff frequency of an amplifier stage |
EP0746959A1 (en) * | 1993-09-20 | 1996-12-11 | Noise Cancellation Technologies, Inc. | Digitally controlled analog cancellation system |
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DE3834316C1 (en) * | 1988-10-08 | 1989-10-26 | Eurion Ag, Rapperswil, Ch | Hearing aid |
US5235637A (en) * | 1989-01-26 | 1993-08-10 | Plantronics, Inc. | Voice communication link interface |
US5303306A (en) * | 1989-06-06 | 1994-04-12 | Audioscience, Inc. | Hearing aid with programmable remote and method of deriving settings for configuring the hearing aid |
EP0419127A3 (en) * | 1989-09-20 | 1991-10-09 | Gennum Corporation | Noise suppression system |
US5131046A (en) * | 1989-11-03 | 1992-07-14 | Etymotic Research Inc. | High fidelity hearing aid amplifier |
NO169689C (en) * | 1989-11-30 | 1992-07-22 | Nha As | PROGRAMMABLE HYBRID HEARING DEVICE WITH DIGITAL SIGNAL TREATMENT AND PROCEDURE FOR DETECTION AND SIGNAL TREATMENT AT THE SAME. |
US5550925A (en) * | 1991-01-07 | 1996-08-27 | Canon Kabushiki Kaisha | Sound processing device |
US5285502A (en) * | 1992-03-31 | 1994-02-08 | Auditory System Technologies, Inc. | Aid to hearing speech in a noisy environment |
US5406633A (en) * | 1992-11-03 | 1995-04-11 | Auditory System Technologies, Inc. | Hearing aid with permanently adjusted frequency response |
US6072885A (en) * | 1994-07-08 | 2000-06-06 | Sonic Innovations, Inc. | Hearing aid device incorporating signal processing techniques |
US8085959B2 (en) * | 1994-07-08 | 2011-12-27 | Brigham Young University | Hearing compensation system incorporating signal processing techniques |
US5550923A (en) * | 1994-09-02 | 1996-08-27 | Minnesota Mining And Manufacturing Company | Directional ear device with adaptive bandwidth and gain control |
US5825898A (en) * | 1996-06-27 | 1998-10-20 | Lamar Signal Processing Ltd. | System and method for adaptive interference cancelling |
FR2756086A1 (en) * | 1996-11-19 | 1998-05-22 | Philips Electronics Nv | ROAD SIGNALING APPARATUS COMPRISING LIGHTING ORGANS LOCATED ON THE GROUND |
US6359992B1 (en) * | 1997-02-06 | 2002-03-19 | Micro Ear Technology | Acoustics conditioner |
US6178248B1 (en) | 1997-04-14 | 2001-01-23 | Andrea Electronics Corporation | Dual-processing interference cancelling system and method |
US6363345B1 (en) | 1999-02-18 | 2002-03-26 | Andrea Electronics Corporation | System, method and apparatus for cancelling noise |
US6408318B1 (en) | 1999-04-05 | 2002-06-18 | Xiaoling Fang | Multiple stage decimation filter |
US6594367B1 (en) | 1999-10-25 | 2003-07-15 | Andrea Electronics Corporation | Super directional beamforming design and implementation |
US6633202B2 (en) | 2001-04-12 | 2003-10-14 | Gennum Corporation | Precision low jitter oscillator circuit |
US6937738B2 (en) * | 2001-04-12 | 2005-08-30 | Gennum Corporation | Digital hearing aid system |
EP1251355B1 (en) * | 2001-04-18 | 2007-12-05 | Gennum Corporation | Digital quasi-rms detector |
EP1251715B2 (en) * | 2001-04-18 | 2010-12-01 | Sound Design Technologies Ltd. | Multi-channel hearing instrument with inter-channel communication |
US20020191800A1 (en) * | 2001-04-19 | 2002-12-19 | Armstrong Stephen W. | In-situ transducer modeling in a digital hearing instrument |
US7274794B1 (en) | 2001-08-10 | 2007-09-25 | Sonic Innovations, Inc. | Sound processing system including forward filter that exhibits arbitrary directivity and gradient response in single wave sound environment |
DK1284587T3 (en) * | 2001-08-15 | 2011-10-31 | Sound Design Technologies Ltd | Reconfigurable low energy hearing aid |
KR20030096847A (en) * | 2002-06-18 | 2003-12-31 | 세기스타 주식회사 | Circuit of pocket type hearing aid |
US7171010B2 (en) * | 2003-09-11 | 2007-01-30 | Boston Acoustics, Inc. | Dynamic bass boost apparatus and method |
US7529378B2 (en) * | 2004-11-12 | 2009-05-05 | Phonak Ag | Filter for interfering signals in hearing devices |
US20060140416A1 (en) * | 2004-12-23 | 2006-06-29 | Phonak Ag | Active hearing protection system and method |
JP5688547B2 (en) * | 2010-11-22 | 2015-03-25 | パナソニックIpマネジメント株式会社 | Audio processing device, sound collection device, and imaging device |
US8693716B1 (en) | 2012-11-30 | 2014-04-08 | Gn Resound A/S | Hearing device with analog filtering and associated method |
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-
1986
- 1986-03-31 US US06/846,662 patent/US4750207A/en not_active Expired - Lifetime
-
1987
- 1987-03-18 EP EP87104004A patent/EP0240798A1/en not_active Withdrawn
- 1987-03-25 DK DK150587A patent/DK150587A/en not_active IP Right Cessation
- 1987-03-25 JP JP62072959A patent/JPS62242500A/en active Pending
- 1987-03-27 CA CA000533200A patent/CA1273097A/en not_active Expired - Fee Related
Patent Citations (4)
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---|---|---|---|---|
US3927279A (en) * | 1972-10-16 | 1975-12-16 | Rion Co | Hearing aid |
DE3139088A1 (en) * | 1981-10-01 | 1983-04-14 | Robert Bosch Gmbh, 7000 Stuttgart | Hearing device |
DE3237988A1 (en) * | 1981-10-13 | 1983-05-19 | Rion K.K., Kokubunji, Tokyo | HOERGERAET |
US4506381A (en) * | 1981-12-29 | 1985-03-19 | Mitsubishi Denki Kabushiki Kaisha | Aural transmitter device |
Non-Patent Citations (3)
Title |
---|
HEARING INSTRUMENTS, vol. 37, no. 2, February 1986, pages 19-20,22, Cleveland, US; J.M. KATES: "Signal processing for hearing aids" * |
PATENT ABSTRACTS OF JAPAN, vol. 4, no. 56 (E-8)[538], 25th April 1980; & JP-A-55 27 742 (SUWA SEIKOSHA K.K.) 28-02-1980 * |
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 88 (E-240)[125], 21st April 1984; & JP-A-59 008 500 (MINOLTA CAMERA K.K.) 17-01-1984 * |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2635680A1 (en) * | 1988-08-30 | 1990-03-02 | Belone Electronics Corp | HEARING AID |
US5170434A (en) * | 1988-08-30 | 1992-12-08 | Beltone Electronics Corporation | Hearing aid with improved noise discrimination |
AU637722B2 (en) * | 1990-10-30 | 1993-06-03 | Ascom Audiosys Ag | A method of supressing noise in hearing aids |
EP0635937A1 (en) * | 1993-07-22 | 1995-01-25 | Eastman Kodak Company | Circuit for controlling the overall upper cutoff frequency of an amplifier stage |
EP0746959A1 (en) * | 1993-09-20 | 1996-12-11 | Noise Cancellation Technologies, Inc. | Digitally controlled analog cancellation system |
EP0746959A4 (en) * | 1993-09-20 | 2001-10-17 | Noise Cancellation Tech | Digitally controlled analog cancellation system |
Also Published As
Publication number | Publication date |
---|---|
DK150587D0 (en) | 1987-03-25 |
JPS62242500A (en) | 1987-10-23 |
CA1273097A (en) | 1990-08-21 |
US4750207A (en) | 1988-06-07 |
DK150587A (en) | 1987-10-01 |
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