System and method for automatic multiple listener room acoustic correction with low filter orders

• US 8,005,228 B2
• Filed: 04/10/2009
• Issued: 08/23/2011
• Est. Priority Date: 06/21/2002
• Status: Expired due to Term

• Current Assignee: Audyssey Laboratories, Inc.
• Original Assignee: Audyssey Laboratories, Inc.
• Inventors: Kyriakakis, Chris, Bharitkar, Sunil
• Primary Examiner(s): Faulk; Devona E
• Assistant Examiner(s): MONIKANG, GEORGE C
• Application Number:
  US12/422,117
• Publication Number:
  US 20090202082A1
• Time in Patent Office: 865 Days
• Field of Search: 381 17- 19, 381/58, 381/61, 381/63, 381/77, 381/307, 381/309, 381/83, 381/93, 381/94.1, 381/94.2, 381/300, 381/94.3
• US Class Current: 381/17
• CPC Class Codes: H04S 2400/09 Electronic reduction of distortion of stereophonic sound systems
• CPC Class Codes: H04S 7/30 Control circuits for electronic adaptation of the sound field

Abstract

A system and a methods for correcting, simultaneously at multiple-listener positions, distortions introduced by the acoustical characteristics includes warping room responses, intelligently weighing the warped room acoustical responses to form a weighted response, a low order spectral fitting to the weighted response, forming a warped filter from the low order spectral fit, and unwarping the warped filter to form the room acoustical correction filter.

Claims

1. A method for correcting room acoustics at multiple-listener positions, the method comprising:

measuring with a microphone a room acoustical response at each listener position in a multiple-listener environment;

processing each of the room acoustical response measured at said each listener position to obtain non-uniform resolution of the room acoustical response in an audio frequency domain, wherein the non-uniform resolution results in higher resolution at low frequencies for each of the measured room acoustical response;

determining a general response by computing a weighted average of the processed acoustical responses;

generating a low order spectral model of the general response;

obtaining an acoustic correction filter from the low order spectral model, wherein the acoustic correction filter is the inverse of the low order spectral model; and

processing the acoustic correction filter to obtain a room acoustic correction filter with uniform resolution in the audio frequency domain;

wherein the room acoustic correction filter corrects the room acoustics at the multiple-listener positions.

2. The method of claim 1, further comprising generating a stimulus signal for measuring the room acoustical response at each of the listener positions.

3. The method of claim 1, wherein the general response is determined by a pattern recognition method.

4. The method of claim 3, wherein the pattern recognition method comprises a method selected from a group consisting of:

a hard c-means clustering method, a fuzzy c-means clustering method, and an adaptive learning method.

5. The method of claim 1, wherein the spectral model comprises a model selected from a group consisting of a Linear Predictive Coding (LPC) model and a pole-zero model.

6. The method of claim 1, wherein the processing comprises psycho-acoustically motivated warping.

7. The method of claim 6, wherein the warping is achieved by means of a bilinear conformal map.

8. The method of claim 6, wherein the psycho-acoustically motivated warping is accomplished in the frequency domain.

9. A method for correcting room acoustics at multiple-listener positions, the method comprising:

measuring with a microphone a room acoustical response at each listener position in a multiple-listener environment;

processing each of the room acoustical response measured at said each listener position to obtain non-uniform resolution of the room acoustical response in an audio frequency domain, wherein the non-uniform resolution results in higher resolution at low frequencies for each of the measured room acoustical response;

obtaining minimum-phase response of each of the said processed acoustical responses;

determining a general response by computing the weighted average of the minimum-phase processed responses;

generating a low order spectral model of the general response;

obtaining an acoustic correction filter from the low order spectral model; and

processing the acoustic correction filter to obtain a room acoustic correction filter with uniform resolution in the audio frequency domain;

wherein the room acoustic correction filter corrects the room acoustics at the multiple-listener positions.

10. The method of claim 9, further comprising generating a stimulus signal for measuring the room acoustical response at each of the listener positions.

11. The method of claim 9, wherein the general response is determined by a pattern recognition method.

12. The method of claim 11, wherein the pattern recognition method comprises a method selected from a group consisting of:

a hard c-means clustering method, a fuzzy c-means clustering method, and an adaptive learning method.

13. The method of claim 9, wherein the processing comprises psycho-acoustically motivated warping.

14. The method of claim 13, wherein the warping is achieved by means of a bilinear conformal map.

15. The method of claim 13, wherein the psycho-acoustically motivated warping is accomplished in the frequency domain.

16. The method of claim 9, wherein the spectral model comprises a model selected from a group consisting of a Linear Predictive Coding (LPC) model and a pole-zero model.