Microphone array system

• US 6,760,449 B1
• Filed: 10/12/1999
• Issued: 07/06/2004
• Est. Priority Date: 10/28/1998
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Matsuo, Naoshi
• Primary Examiner(s): Isen, F. W.
• Assistant Examiner(s): MCCHESNEY, ELIZABETH A
• Application Number:
  US09/415,504
• Time in Patent Office: 1,729 Days
• Field of Search: 381/92, 381/122
• US Class Current: 381/92
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A microphone array system includes a plurality of microphones and a sound signal processing part. The microphones are arranged in such a manner that at least three microphones are arranged in a first direction to form a microphone row, at least three rows of the microphones are arranged so that the microphone rows are not crossed each other so as to form a plane, and at least three layers of the planes are arranged three-dimensionally so that the planes are not crossed each other, so that the boundary conditions for the sound estimation at each plane of the planes constituting the three dimension can be obtained. The sound signal processing part estimates a sound in each direction of the three-dimensional space by estimating sound signals in at least three positions along a direction that crosses the first direction, utilizing the relationship between the gradient on the time axis of the sound pressure and the gradient on the spatial axis of the air particle velocity, and the relationship between the gradient on the spatial axis of the sound pressure and the gradient on the time axis of the air particle velocity, and based on a temporal variation of the sound pressure of the received sound signals of the arranged microphones in each spatial axis direction and a spatial variation of the received sound signals of the arranged microphones.

Claims

1. A microphone array system comprising a plurality of microphones and a sound signal processing part,

wherein at least three microphones are arranged on each spatial axis, and

the sound signal processing part estimates a sound signal in an arbitrary position in a space by estimating a sound signal to be received at each axis component in the arbitrary position, utilizing a relationship between a difference, which is a gradient, between neighborhood points on a time axis of a sound pressure of a received sound signal of each microphone and a difference, which is a gradient, between neighborhood points on a spatial axis of an air particle velocity, and a relationship between a difference, which is a gradient, between neighborhood points on a spatial axis of the sound pressure and a difference, which is a gradient, between neighborhood points on a time axis of the air particle velocity, and based on a temporal variation of the sound pressure and a spatial variation of the air particle velocity of the received sound signal of each microphone arranged in each spatial axis direction;

and synthesizing the estimated signals three-dimensionally.

2. The microphone array system according to claim 1, wherein in the estimation of a sound signal in an arbitrary position in a space, the sound signal estimation processing for each spatial axis direction is performed on a premise that an influence of a variation in the sound pressure and the air particle velocity of a sound signal in one spatial axis direction on a variation in the sound pressure and the air particle velocity of a sound signal in another spatial axis direction can be ignored.

3. A microphone array system comprising a plurality of microphones and a sound signal processing part,

wherein the microphones are arranged in such a manner that at least three microphones are arranged in a first direction to form a microphone row, at least three rows of the microphones are arranged so that the microphone rows are not crossed each other so as to form a plane, and at least three layers of the planes are arranged three-dimensionally so that the planes are not crossed each other, so that boundary conditions for sound estimation at each plane of the planes constituting a three dimension can be obtained, and

the sound signal processing part estimates a sound in each direction of a three-dimensional space by estimating sound signals in at least three positions along a direction that crosses the first direction, utilizing a relationship between a difference, which is a gradient, between neighborhood points on a time axis of a sound pressure of a received sound signal of each microphone and a difference, which is a gradient, between neighborhood points on a spatial axis of an air particle velocity, and a relationship between a difference, which is a gradient, between neighborhood points on a spatial axis of the sound pressure and a difference, which is a gradient, between neighborhood points on a time axis of the air particle velocity, and based on a temporal variation of the sound pressure and a spatial variation of the air particle velocity of received sound signals in at least three positions aligned along the first direction;

and further estimating a sound signal in the direction that crosses the first direction based on the estimated signals in the three positions.

4. The microphone array system according to claim 3, wherein the relationship between a gradient on a time axis of a sound pressure and a gradient on a spatial axis of an air particle velocity of a received sound signal is expressed by Equation 25:

5. The microphone array system according to claim 3, wherein the sound signal processing part comprises a parameter input part for receiving an input of parameter that adjusts a signal processing content.

6. The microphone array system according to claim 3, wherein an interval distance between adjacent microphones of the arranged microphones is within a distance that satisfies a sampling theorem on a spatial axis for a frequency of a sound signal to be received.

7. The microphone array system according to claim 3, comprising a microphone interval distance adjusting part for changing and adjusting an interval distance between the arranged microphones.

8. The microphone array system according to claim 3, wherein the sound signal processing part comprises a microphone position interpolation processing part for changing and adjusting an interval distance between the arranged microphones virtually by performing position-interpolation-processing with respect to a signal received by each of the microphones.

9. The microphone array system according to claim 3, wherein the sound signal processing part comprises a sampling frequency adjusting part for adjusting a sampling frequency for the processing of sounds to be received at the microphones.

10. The microphone array system according to claim 3, wherein the sound signal processing part comprises a band processing part for performing band division processing and frequency shift for band synthesis for a received sound signal at the microphones.

11. The microphone array system according to claim 3, wherein a sound signal enhancement direction parameter for designating a specific direction in which sound signal is enhanced is supplied to the parameter input part, thereby enhancing a sound signal from a sound source in the specific direction.

12. The microphone array system according to claim 3, wherein a sound signal attenuation direction parameter for designating a specific direction in which sound signal is reduced is supplied to the parameter input part, thereby removing a sound signal from a sound source in the specific direction.

13. The microphone array system according to claim 3, which estimates a position of a sound source by detecting a position having a largest cross-correlation, based on estimated sound signals in a plurality of arbitrary positions in a sound field and utilizing a cross-correlation function between the estimated sound signals.

14. The microphone array system according to claim 3, wherein the sound signal processing part comprises a sound power detecting part, and checks a power of a synchronous added sound signal with respect to a direction with the sound power detecting part, so as to detect whether or not there is a sound source in the direction.

15. The microphone array system according to claim 3, wherein the microphones are mutually coupled and supported on a predetermined spatial axis.

16. A microphone array system comprising a plurality of directional microphones and a sound signal processing part,

wherein at least two directional microphones are arranged with directivity on each spatial axis, and

the sound signal processing part estimates a sound signal in an arbitrary position in a space by estimating a sound signal to be received at each axis component in the arbitrary position utilizing a relationship between a difference, which is a gradient, between neighborhood points on a time axis of a sound pressure of a received sound signal of each microphone and a difference, which is a gradient, between neighborhood points on a spatial axis of an air particle velocity, and a relationship between a difference, which is a gradient, between neighborhood points on a spatial axis of the sound pressure and a difference, which is a gradient, between neighborhood points on a time axis of the air particle velocity, and based on a temporal variation of the sound pressure and a spatial variation of the air particle velocity of a received sound signal of each of the directional microphones arranged in each spatial axis direction;

and synthesizing the estimated signals three-dimensionally.

17. A microphone array system comprising a plurality of directional microphones and a sound signal processing part,

wherein the directional microphones are arranged in such a manner that at least two directional microphones are arranged with directivity to a first direction to form a microphone row, at least two rows of the directional microphones are arranged so that the microphone rows are not crossed each other so as to form a plane, and at least two layers of the planes are arranged three-dimensionally so that the planes are not crossed each other, so that boundary conditions for sound estimation at each plane of the planes constituting a three dimension can be obtained, and

the sound signal processing part estimates a sound in each direction of a three-dimensional space by estimating sound signals in at least two positions along a direction that crosses the first direction, utilizing a relationship between a difference, which is a gradient, between neighborhood points on a time axis of a sound pressure of a received sound signal of each microphone and a difference, which is a gradient, between neighborhood points on a spatial axis of an air particle velocity, and a relationship between a difference, which is a gradient, between neighborhood points on a spatial axis of the sound pressure and a difference, which is a gradient, between neighborhood points on a time axis of the air particle velocity, and based on a temporal variation of the sound pressure and a spatial variation of the air particle velocity of received sound signals in at least two positions aligned along the first direction;

and further estimating a sound signal in the direction that crosses the first direction based on the estimated signals in the two positions.

18. The microphone array system according to claim 17, wherein the relationship between a gradient on a time axis of a sound pressure and a gradient on a spatial axis of an air particle velocity of a received sound signal is expressed by Equation 26:

19. The microphone array system according to claim 17, wherein the sound signal processing part comprises a parameter input part for receiving an input of parameter that adjusts a signal processing content.

20. The microphone array system according to claim 17, wherein an interval distance between adjacent microphones of the arranged microphones is within a distance that satisfies a sampling theorem on a spatial axis for a frequency of a sound signal to be received.

21. The microphone array system according to claim 17, comprising a microphone interval distance adjusting part for changing and adjusting an interval distance between the arranged microphones.

22. The microphone array system according to claim 17, wherein the sound signal processing part comprises a microphone position interpolation processing part for changing and adjusting an interval distance between the arranged microphones virtually by performing position-interpolation-processing with respect to a signal received by each of the microphones.

23. The microphone array system according to claim 17, wherein the sound signal processing part comprises a sampling frequency adjusting part for adjusting a sampling frequency for the processing of sounds to be received at the microphones.

24. The microphone array system according to claim 17, wherein the sound signal processing part comprises a band processing part for performing band division processing and frequency shift for band synthesis for a received sound signal at the microphones.

25. The microphone array system according to claim 17, wherein a sound signal enhancement direction parameter for designating a specific direction in which sound signal is enhanced is supplied to the parameter input part, thereby enhancing a sound signal from a sound source in the specific direction.

26. The microphone array system according to claim 17, wherein a sound signal attenuation direction parameter for designating a specific direction in which sound signal is reduced is supplied to the parameter input part, thereby removing a sound signal from a sound source in the specific direction.

27. The microphone array system according to claim 17, which estimates a position of a sound source by detecting a position having a largest cross-correlation, based on estimated sound signals in a plurality of arbitrary positions in a sound field and utilizing a cross-correlation function between the estimated sound signals.

28. The microphone array system according to claim 17, wherein the sound signal processing part comprises a sound power detecting part, and checks a power of a synchronous added sound signal with respect to a direction with the sound power detecting part, so as to detect whether or not there is a sound source in the direction.

30. The microphone array system according to claim 17, wherein the microphones are mutually coupled and supported on a predetermined spatial axis.

29. A microphone array system comprising a plurality of microphones and a sound signal processing part,

wherein a plurality of microphones are arranged in three mutually orthogonal axis directions in a predetermined space, in which at least three of said microphones are arranged in each of said orthogonal axis directions, and

the sound signal processing part connected to the microphones estimates a sound signal in an arbitrary position in a space other than the space where the microphones are arranged based on a relationship between positions where the microphones are arranged and received sound signals.