WO2005073680A1

WO2005073680A1 - An apparatus for measuring and analysing sound signals

Info

Publication number: WO2005073680A1
Application number: PCT/DK2005/000059
Authority: WO
Inventors: Peter Larsen
Original assignee: Bruel & Kjær Sound & Vibration Measurement A/S
Priority date: 2004-01-30
Filing date: 2005-01-28
Publication date: 2005-08-11
Also published as: DK200400135A

Abstract

An apparatus for measuring and analysing sound signals has a measuring microphone (Ml) and an analysing circuit analysing the signals output from the first microphone (Ml). A second microphone (M2) receives voice signals from an operator, and a storage stores the both the analysis results and the voice signals. A camera (CAM) can take pictures, and the storage stores both the analysis results and pictures taken by the camera. The apparatus gives new and better possibilities of annotating and documenting measurements and analysis results.

Description

An apparatus for measuring and analysing sound signals

Field of the invention

The invention relates to professional and scientific measurement and analysis of sound. Such measurement and analysis of sound are required e.g. to ascertain whether noise limits in environmental and occupational health standards are exceeded or not.

Background of the invention

Measurements and analyses of environmental and occupational noise must meet rigorous standards. Depending on whether a noise limit is exceeded or not, the consequences thereof on the individuals that are exposed to the noise and on the noise producing party can be dramatic. It is therefore important that measurements of environmental and occupational noise are accurate and reliable.

US 6 035 341 discloses multimedia data analysis in intelligent video informa- tion management system, which accepts and stores input signals from several video cameras and from several microphones. Sound signals from microphones can be analysed and compared with frequency distribution templates representing predefined events, and each template is used for identifying and declaring a specific event.

WO 98/10246 A1 discloses a handheld portable digital geographical data manager for gathering image and other field data, however without the possibility of analysing sequences of data and storing analysis results.

US 2002/0181721 A1 discloses a system with a two-dimensional array of spaced microphones for locating a sound source Traditionally, the operator of equipment for professional and scientific measurement and analysis of environmental and occupational noise has used paper to make notes and sketches of measurement locations, date and time of the day, instrument settings, and meteorological observations such as wind and its direction etc. Proper and carefully made notes and sketches add to the reliability and repeatability of the measurements. However, such notes on paper can be confused with each other, and inaccurate or incomplete notes and sketches may lead to false analyses, and wrong decisions may be made based thereupon.

Noise pulses to be analysed can have durations of a fraction of a second, and environmental and occupational noise measurements can be performed over a period of time, e.g. minutes, hours or days, or continuously. Signals received from measuring microphones can be stored on mass storage devices such as recording tape for later analysis, or analysis, such as frequency analysis, can be performed where only the analysis results are stored, e.g. electronically or on hard copy such as paper. This requires considerably less storage capacity than storing the microphone signals, but great care by the operator is required for properly documenting and annotating the measurements. It can be difficult, or even impossible, to identify a sound event from a third-octave or harmonic analysis alone.

The problem to be solved by the invention is thus to provide an apparatus for measuring and analysing sound signals, where the measurement and analysis results are well documented with no risk of confusion, so that only correct decisions are made based on the measurement and analysis results from the apparatus.

Summary of the invention

The invention solves this problem by providing an apparatus that has new possibilities of annotating the measurement and analysis results concurrently with the measurement and registration of the sound signals. Thus the apparatus has, in addition to the measuring microphone that receives the sound signals to be analysed, an annotation microphone for receiving e.g. voice signals from an operator. This gives the operator the possibility of concur- rently annotating the recorded analysis results by recording voiced comments on the analysed sound signals and on events related to the measuring situation. The operator may also choose to use the annotation microphone pick up an audio sequence of the sound signal that is being analysed and store the audio sequence together with the analysis results. This will greatly assist the operator in identifying events subsequently.

Preferably, the operator's voiced comments should not disturb the measurement and analysis of the sound signals to be measured. Either one of the measurement microphone and the annotation microphone can be placed remotely from the measuring and analysing apparatus, and the signals from the remote microphone can be transmitted to the apparatus via an extension cable or via a wireless connection. A remote annotation microphone can be of the bone conduction type for placing e.g. in the bottom of the tragus of the outer ear of a human being, where it picks up bone conducted speech from the operator. The operator then has both hands free for other purposes. If the surrounding sound to be measured and analysed is very loud, the operator can wear hearing protectors with cups covering the ears, whereby the surrounding sound is correspondingly attenuated before it reaches the annotation microphone, which only picks up the operator's bone conducted speech signals. Transmission of the operator's voice signals to the measuring appa- ratus can take place over a wireless connection such as a Bluetooth link.

Usually, the analysis results require much less storage capacity than the original or compressed sound signals. Preferably, the apparatus stores the analysis results and not the sound signals, whereby the required storage capacity is reduced. The original sound can then no longer be recreated, and it can be difficult to identify a sound event or a sound source based only on the analysis results. In such cases it can be very useful to use the annotation microphone for picking up the sound that is being analysed and store a sample of the sound as a sound file concurrently with the analysis results. The ' operator can initiate such recording manually, or it can be made automati- cally based on certain events. When reviewing the stored analysis results stored samples of the analysed sound can greatly assist in identifying the sound source or event that created the sound.

The apparatus of the invention preferably has a camera that can take still pictures and video sequences and is used for taking pictures of e.g. the measuring location and of events relating thereto. The user can make selected pictures showing the measuring location and of objects such as buildings that can influence the measurements, or of selected sequences of the measuring session. The apparatus can be programmed to take pictures at certain conditions such as the sound level exceeding a preset threshold or triggered by the operator. Such still pictures and video sequences are stored in the storage together with the corresponding sound signals or analysis results. The user thus has a powerful tool for documenting the measurements and the events that caused them.

The apparatus of the invention can have other means of annotating the measurements that contribute to the documentation of the measurements. Such means include a clock, a camera for making photographic recordings, a system for identifying the geographical location, and a pressure sensitive screen. Further details and their advantages will become apparent from the following detailed description of the invention. Detailed description of the invention

The figure illustrates schematically an apparatus 10 according to the invention for measuring and analysing sound signals. A measuring microphone M1 receives sound signals to be analysed and outputs electrical signals repre- senting the received sound signals. The measuring microphone M1 is connected to a preamplifier 11 that has as its main task to amplify and condition the output signal from the microphone and feed the amplified signals to the apparatus 10. The measuring microphone M1 is preferably a condenser microphone, which is known to have excellent performance and very high out- put impedance. If appropriate and as shown, there can be an extension cable 12 between the apparatus 10 and the preamplifier 11, so that the measuring microphone M1 can be placed remotely from the apparatus 10.

The apparatus 10 has an electronic circuit 13 that receives the signals from the preamplifier 11. The electronic circuit 13 comprises a circuit 14 for ana- lysing the signals received from the measuring microphone M1 through the preamplifier 11. The analyser 14 is preferably a digital analyser, and is controlled by a controller 15. The analyser 14 is connected to a storage device 16, and analysis results from the analyser 14 are stored in the storage device 16. The stored analysis results from the analyser 14 correspond to a period of time that can be selected by the user or can be selected by the controller depending e.g. on the occurrence of predefined events.

The output signals from the analyser 14 to the storage device 16 are preferably the analysis results in digital form, but the signals from the measuring microphone M1 can also be stored directly.

The analyser comprises filters for analysing the sound signals. Examples of such filters are weighting filters for assessing occupational noise levels, octave and third-octave filters for frequency analysis and narrow band filters for harmonic analysis. The apparatus 10 has an annotation microphone M2 for receiving e.g. voice signals from an operator and for outputting signals representing the voice signals. The signals from the annotation microphone M2 are stored in the storage 16 in parallel with the signals from the analyser 14. This gives the user the possibility of annotating the sound signals to be measured and analysed or the analysis results. Such annotations can be the operator's comments on the measuring setup or to relevant events, and the operator's comments are stored concurrently with the analysis results. Like the measuring microphone M1 the annotation microphone M2 can be remote from the apparatus 10, or it can be built into the apparatus.

For manually inputting commands to the apparatus the operator uses a user interface USER INPUT. The user interface may comprise pushbuttons, switches, and rotary knobs etc that are used for manually setting modes of operation of the apparatus. A switch can be used for activating the annotation microphone M2.

A clock CLK generates time signals that are also stored in the storage 16 concurrently with the signals from the analyser 14 to provide a time-stamping of the stored data. The generated time signals can also be used for performing measurements with predefined start and stop times defined by the user.

A camera CAM can take still pictures and video sequences and is used for taking pictures of e.g. the measuring location and of events relating thereto. Pictures and video sequences taken with the camera are stored in the storage together with the corresponding sound signals or analysis results.

For documenting the exact geographical location of the measurement the apparatus has a built-in receiver GPS for receiving signals e.g. from the satellite-based Global Positioning System enabling the apparatus to calculate and document exact geographical location. Such data is stored in the storage together with the corresponding sound signals or analysis results. Instead of a built-in GPS receiver the apparatus can be connected to an external receiver.

When setting up the apparatus for measurement the operator can use both the above-mentioned user interface and a screen 17 that is used as an inter- active visual and graphical interface with the operator. The screen 17 is used to display menus and settings of the apparatus. The screen 17 is touch sensitive, and the operator can select menu options by touching the appropriate places on the screen with a suitable instrument such as a dedicated stylus or a writing implement, and the operator can draw sketches e.g. of the measur- ing location, which is also stored in the storage together with the corresponding sound signals or analysis results.

The apparatus has a connector for making a connection 18 to external equipment EXT. Examples of possible external equipment is a computer that controls the apparatus and reads its stored data for further processing, exter- nal memory such as a memory card, an analysis and documentation system, software for download to the apparatus, communication over the Internet or using a wireless connection using e.g. the Bluetooth protocol.

Claims

1. An apparatus for measuring and analysing sound signals, the apparatus comprising

- a first microphone (M1 ) for receiving the sound signals to be analysed and for outputting signals representing received sound signals,

- an analysing circuit arranged to receive and analyse the signals output from the first microphone (M1 ), and to output corresponding analysis results,

- a second microphone (M2) for receiving voice signals from an operator and for outputting signals representing received voice signals, and

- a storage arranged to receive and store the analysis results from the analysing circuit and the signals representing received voice signals.

2. An apparatus according to claim 1 further comprising a camera for taking pictures, wherein the storage is arranged to receive and store pictures taken by the camera.

3. An apparatus for measuring and analysing sound signals, the apparatus comprising

- a camera for taking pictures, and

- a storage arranged to receive and store the analysis results from the analysing circuit and pictures taken by the camera.

4. An apparatus according to claim 4 further comprising a second microphone (M2) for receiving voice signals from an operator and for outputting signals representing received voice signals, wherein the storage is arranged to receive and store the signals representing received voice signals.

5. An apparatus according to any one of claims 1-4 comprising a clock (CLK) outputting time signals, and wherein the storage is arranged to receive and to store the time signals.

6. An apparatus according to any one of claims 1-5, comprising a wired or wireless connection (12) for placing the first microphone (M1 ) or the second microphone (M2) remotely from the apparatus.

7. An apparatus according to any one of claims 1-6, comprising means (GPS) providing information for determining the global position of the apparatus, and wherein the storage is arranged to receive and to store such information.

8. An apparatus according to any one of claims 1-7, comprising an interactive visual and graphical interface with the operator.

9. An apparatus according to claim 8, wherein the interactive visual and graphical interface is a touch sensitive screen.