Apparatus and method of determining an impulse response and apparatus and method of presenting an audio piece

• US 20050207592A1
• Filed: 05/13/2005
• Published: 09/22/2005
• Est. Priority Date: 11/21/2002
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Neubauer, Christian, Sporer, Thomas
• Granted Patent: US 7,881,485 B2
• Time in Patent Office: Days
• US Class Current: 381/94.200
• CPC Class Codes: H04R 29/007 for public address systems public address systems per se H04R27/00
• CPC Class Codes: H04S 2420/13 Application of wave-field synthesis in stereophonic audio systems
• CPC Class Codes: H04S 7/30 Control circuits for electronic adaptation of the sound field

Abstract

The apparatus for determining an impulse response in an environment in which a speaker and a microphone are placed works using an audio signal. Means for spectrally coloring a test signal, which preferably is a pseudonoise signal, works using a psychoacoustic masking threshold of the audio signal to obtain a colored test signal, which is embedded in the audio signal to obtain a measuring signal, which can be fed to the speaker. Means for determining the impulse response preferably performs a cross-correlation of a reaction signal received via the microphone from the environment and the test signal or the colored test signal. With this, an impulse response of an environment may also be determined during the presentation of an audio piece to provide an optimal description of environment for a wave-field synthesis.

Claims

1. An apparatus for determining an impulse response in an environment in which a speaker and a microphone are placed, using an audio signal, comprising:

a processor for spectrally coloring a test signal using a psychoacoustic masking threshold of the audio signal;

an introducer for introducing the colored test signal into the audio signal to obtain a measuring signal, which may be fed to the speaker; and

a calculator for calculating the impulse response using a reaction signal received via the microphone from the environment and the test signal or the colored test signal.

2. The apparatus of claim 1, wherein the calculator is formed to perform a cross-correlation of the reaction signal received via the microphone from the environment and the test signal or the colored test signal.

3. The apparatus of claim 1, wherein the test signal is a pseudonoise signal.

4. The apparatus of claim 1, wherein the processor for spectrally coloring is formed to color the test signal such that a spectral course of the colored test signal lies below the spectral psychoacoustic masking threshold of the audio signal so that the colored test signal is not audible in the measuring signal.

5. The apparatus of claim 1, wherein the environment comprises several speakers and several microphones, wherein for a channel from a speaker to a microphone an impulse response is defined, wherein the apparatus further comprises:

a controller for controlling the introducer such that it introduces a colored test signal into audio signals for the several speakers in order to generate a measuring signal of its own for each speaker, wherein the controller is further formed to sequentially apply measuring signals on the speakers; and

an identifier for identifying an obtained impulse response regarding the speaker from which a generated measuring signal originates and regarding the microphone from which an associated reaction signal originates.

6. The apparatus of claim 2, wherein the environment comprises several speakers and several microphones, wherein for a channel from a speaker to a microphone an impulse response is defined, wherein the apparatus further comprises:

a controller for controlling the introducer such that it introduces a colored test signal into audio signals for several speakers in order to generate a measuring signal of its own for each speaker, wherein the controller is further formed to base each measuring signal on a test signal of its own, wherein test signals are mutually orthogonal for various measuring signals; and

wherein for each microphone a calculator of its own for cross-correlation is provided, which may be used for cross-correlating the orthogonal test signals, and

an identifier for identifying an obtained impulse response using the microphone with which the calculator for cross-correlating is associated by which the obtained impulse response is calculated, and by the speaker with which the corresponding test signal is associated, which is employed for obtaining the impulse response.

7. The apparatus of claim 2, wherein the calculator for calculating the impulse response is formed to postprocess a cross-correlation result using information on the processor for spectrally coloring in order to obtain an impulse response independent of the psychoacoustic masking threshold of the audio signal.

8. The apparatus of claim 2, wherein the calculator for calculating the impulse response is formed to obtain the cross-correlated iterative multiplication of the reaction signal and a conjugated complex transposed representation of the test signal, and summation of multiplication results in order to obtain an improved estimation of the impulse response with each iteration step.

9. The apparatus of claim 2, wherein the audio signal is an audio signal to be presented in the environment.

10. The apparatus of claim 1, wherein the audio signal is a music signal.

11. The apparatus of claim 1, wherein the speaker may be employed as microphone in an impulse response measuring mode.

12. An apparatus for presenting an audio piece in an environment in which several speakers and several microphones are placed, comprising:

a performer for performing a wave-field synthesis to calculate audio signals for the plurality of speakers on the basis of the audio piece; and

a determinator for determining the impulse response in the environment in which a speaker and a microphone are placed, using an audio signal, comprising;

a processor for spectrally coloring a test signal using a psychoacoustic masking threshold of the audio signal;

an introducer for introducing the colored test signal into the audio signal to obtain a measuring signal, which may be fed to the speaker; and

a calculator for calculating the impulse response using a reaction signal received via the microphone from the environment and the test signal or the colored test signal,

wherein the determinator is formed to calculate a current impulse response during presenting the audio piece,

wherein the performer for performing the wave-field synthesis is controllable to take a current impulse response into account in a calculation of the audio signal for the plurality of speakers during the presentation of the audio piece.

13. The apparatus of claim 12, wherein the environment when presenting the audio piece differs regarding its impulse response from the environment when no audio piece is presented.

14. The apparatus of claim 13, wherein a difference in the environment is that a number of people deviates from one situation to the next situation or that no people are in the environment.

15. The apparatus of claim 12, wherein the environment is a concert hall, a movie theater, or an audio presentation room at home.

16. The apparatus of claim 12, wherein the performer for performing the wave-field synthesis is formed to calculate positions of sound excitation sources and sound reflection sources due to an impulse response of the environment and takes them into account in the calculation of the audio signal for the plurality of speakers.

17. The apparatus of claim 16, wherein the performer for performing the wave-field synthesis is formed to take the current impulse response into account starting from a start setting, wherein the determinator for determining the impulse response is formed to calculate the impulse response for the starting representation like the current impulse response or without audio signal and using an uncolored test signal.

18. The apparatus of claim 12, wherein the microphones are placed remotely from the speakers or between the speakers.

19. The apparatus of claim 12, wherein the microphones are arranged in a circular, a linear, or a cross-shaped array.

20. The apparatus of claim 19, wherein the microphones are moved between individual cross-correlation calculations.

21. A method of determining an impulse response in an environment in which a speaker and a microphone are placed, using an audio signal, comprising:

spectrally coloring a test signal using a psychoacoustic masking threshold of the audio signal;

introducing the colored test signal into the audio signal to obtain a measuring signal, which can be fed to the speaker; and

calculating the impulse response using a reaction signal received via the microphone from the environment and the test signal or the colored test signal.

22. A method of presenting an audio piece in an environment in which several speakers and several microphones are placed, comprising:

performing a wave-field synthesis to calculate audio signals for the plurality of speakers on the basis of the audio piece; and

determining the impulse response in the environment in which a speaker and a microphone are placed, using an audio signal, comprising;

a processor for spectrally coloring a test signal using a psychoacoustic masking threshold of the audio signal;

an introducer for introducing the colored test signal into the audio signal to obtain a measuring signal, which may be fed to the speaker; and

a calculator for calculating the impulse response using a reaction signal received via the microphone from the environment and the test signal or the colored test signal,

wherein the determinator is formed to calculate a current impulse response while presenting the audio piece,

wherein the performer for performing the wave-field synthesis is controllable to take a current impulse response into account in a calculation of the audio signals for the plurality of speakers during the presentation of the audio piece.

23. A computer program with a program code for performing, when the program is executed on a computer, the method of determining an impulse response in an environment in which a speaker and a microphone are placed, using an audio signal, comprising:

spectrally coloring a test signal using a psychoacoustic masking threshold of the audio signal;

introducing the colored test signal into the audio signal to obtain a measuring signal, which can be fed to the speaker; and

calculating the impulse response using a reaction signal received via the microphone from the environment and the test signal or the colored test signal.

24. A computer program with a program code for performing, when the program is executed on a computer, the method of presenting an audio piece in an environment in which several speakers and several microphones are placed, comprising:

performing a wave-field synthesis to calculate audio signals for the plurality of speakers on the basis of the audio piece; and

determining the impulse response in the environment in which a speaker and a microphone are placed, using an audio signal, comprising;

a processor for spectrally coloring a test signal using a psychoacoustic masking threshold of the audio signal;

an introducer for introducing the colored test signal into the audio signal to obtain a measuring signal, which may be fed to the speaker; and

a calculator for calculating the impulse response using a reaction signal received via the microphone from the environment and the test signal or the colored test signal,

wherein the determinator is formed to calculate a current impulse response while presenting the audio piece,

wherein the performer for performing the wave-field synthesis is controllable to take a current impulse response into account in a calculation of the audio signals for the plurality of speakers during the presentation of the audio piece.