Tracking talkers using virtual broadside scan and directed beams

• US 20060256974A1
• Filed: 04/11/2006
• Published: 11/16/2006
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Lifesize, Inc. (Enghouse Systems Limited)
• Original Assignee: Lifesize, Inc. (Enghouse Systems Limited)
• Inventors: Oxford, William V.
• Granted Patent: US 7,970,150 B2
• Time in Patent Office: Days
• US Class Current: 381/66
• CPC Class Codes: H04R 2225/41 Detection or adaptation of hearing aid parameters or programs to listening situation, e.g. pub, forest
• CPC Class Codes: H04R 2430/23 Direction finding using a sum-delay beam-former
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A communication system (e.g., a speakerphone) includes an array of microphones, a speaker, memory and a processor. The processor may be configured to perform acoustic echo cancellation, to track multiple talkers with highly directed beams, to design beams with nulls pointed at noise sources, to generate a 3D model of the physical environment, to compensate for the proximity effect, and to perform dereverberation of a talker'"'"'s voice signal. The processor may also be configured to use a standard codec in non-standard ways. The processor may perform a virtual broadside scan on the microphone array, analyze the resulting amplitude envelope for acoustic source angles, examine each of the source angles with a directed beam, combine the beam outputs that show the characteristics of intelligence or speech.

Claims

1. A method comprising:

(a) identifying one or more angles of one or more acoustic sources from peaks in an amplitude envelope, wherein the amplitude envelope corresponds to an output of a virtual broadside scan on blocks of input signal samples, one block from each microphone in an array of microphones;

(b) for each of the source angles, operating on the input signal blocks with a directed beam pointed in the direction of the source angle to obtain a corresponding beam signal;

(c) classifying each source as intelligence or noise based on analysis of spectral characteristics of the corresponding beam signal;

(d) of those one or more sources that are classified as intelligence, identifying one or more sources whose corresponding beams signals have highest energies;

(e) generating an output signal from the one or more beam signals corresponding to the one or more intelligence sources having highest energies.

2. The method of claim 1 further comprising:

performing a virtual broadside scan on the blocks of input signal samples to generate the amplitude envelope.

3. The method of claim 2 further comprising:

repeating said performing and operations (a) through (e) on successive sets of input signal sample blocks from the array of microphones.

4. The method of claim 1 further comprising:

transmitting the output signal to one or more devices.

5. The method of claim 1, wherein the one or more intelligence sources having highest energies includes two or more simultaneous talkers.

6. The method of claim 1, wherein the microphones of said array are arranged on a circle.

7. The method of claim 1, wherein the microphones of said array are arranged in a plane.

8. The method of claim 1, wherein the microphones of said array are omni-directional microphones.

9. The method of claim 1, wherein said identifying one or more. angles of one or more acoustic sources from peaks in an amplitude envelope comprises:

estimating an angular position of a first peak in the amplitude envelope;

constructing a shifted and scaled version of a virtual broadside response pattern using the angular position and an amplitude of the first peak;

subtracting the shifted and scaled version from the amplitude envelope to obtain an update to the amplitude envelope.

10. The method of claim 9 further comprising repeating said estimating, said constructing, and said subtracting on the updated amplitude envelope in order to identify a second peak.

11. A computer readable memory medium configured to store program instructions, wherein the program instructions are executable to implement:

(a) identifying one or more angles of one or more acoustic sources from peaks in an amplitude envelope, wherein the amplitude envelope corresponds to an output of a virtual broadside scan on blocks of input signal samples, one block from each microphone in an array of microphones;

(b) for each of the source angles, operating on the input signal blocks with a directed beam pointed in the direction of the source angle to obtain a corresponding beam signal;

(c) classifying each source as intelligence or noise based on analysis of spectral characteristics of the corresponding beam signal;

(d) of those one or more sources that are classified as intelligence, identifying one or more sources whose corresponding beams signals have highest energies;

(e) generating an output signal from the one or more beam signals corresponding to the one or more intelligence sources having highest energies.

12. The memory medium of claim 11 wherein the program instructions are executable to further implement:

performing a virtual broadside scan on the blocks of input signal samples to generate the amplitude envelope.

13. The memory medium of claim 12 wherein the program instructions are executable to further implement:

repeating said performing and operations (a) through (e) on successive sets of input signal sample blocks from the array of microphones.

14. The memory medium of claim 11 wherein the program instructions are executable to further implement:

transmitting the output signal to one or more remote devices.

15. The memory medium of claim 11, wherein the one or more intelligence sources having highest energies includes two or more simultaneous talkers.

16. The memory medium of claim 11, wherein said identifying one or more angles of one or more acoustic sources from peaks in an amplitude envelope comprises:

estimating an angular position of a first peak in the amplitude envelope;

constructing a shifted and scaled version of a virtual broadside response pattern using the angular position and an amplitude of the first peak;

subtracting the shifted and scaled version from the amplitude envelope to obtain an update to the amplitude envelope.

17. The memory medium of claim 16 wherein the program instructions are executable to further implement:

repeating said estimating, said constructing and said subtracting on the updated amplitude envelope.

18. A system comprising:

memory configured to store program instructions;

a processor configured to read and execute the program instructions from the memory,

wherein the program instructions are executable by the processor to implement;

(a) identifying one or more angles of one or more acoustic sources from peaks in an amplitude envelope, wherein the amplitude envelope corresponds to an output of a virtual broadside scan on blocks of input signal samples, one block from each microphone in an array of microphones;

(b) for each of the source angles, operating on the input signal blocks with a directed beam pointed in the direction of the source angle to obtain a corresponding beam signal;

(c) classifying each source as intelligence or noise based on analysis of spectral characteristics of the corresponding beam signal;

(d) of those one or more sources that are classified as intelligence, identifying one or more sources whose corresponding beams signals have highest energies;

(e) generating an output signal from the one or more beam signals corresponding to the one or more intelligence sources having highest energies.

19. The system of claim 18, wherein the microphones of said array are arranged on a circle.

20. The system of claim 18 further comprising said array of microphones.