System and process for sound source localization using microphone array beamsteering
First Claim
1. A system for finding the direction to a sound source from a microphone array in a prescribed search area, comprising:
- a microphone array having a plurality of audio sensors;
a general purpose computing device;
a computer-readable medium having computer-executable instructions, wherein the computing device is directed by the instructions of the computer-readable medium to,(a) package the signals produced by the array microphones into frames,(b) select the frames representing the earliest captured frame of each microphone signal which have not been previously processed,(c) subject the selected frames to a noise suppression procedure,(d) classify the frames based on whether they exhibit evidence of a significant sound source,(e) whenever it is found that the frames do not exhibit evidence of a significant sound source, repeat program modules (b) through (e) as appropriate,(f) whenever it is found that the frames do exhibit evidence of a significant sound source,compute a full spectrum energy comprising an energy value for each of a prescribed set of audio frequency sub-bands within an overall frequency band for a beam in each of a prescribed number of directions, wherein a beam represents a region surrounding a direction extending away from the microphone array wherein sounds originating within that region remain unaffected, while sounds originating outside that region are suppressed, and wherein the prescribed number of directions represent a set of search directions extending away from the microphone array which when a beam is associated with each of the search directions covers the entire search area without significant overlap between adjacent beams extending along those directions, andfor each computed energy value, apply a weighting factor associated with the frequency sub-band of the computed energy value, from a set of weighting factors comprising one for each of said set of audio frequency sub-bands, to the computed energy value, wherein each weighting factor reflects an energy level which is expected to be exhibited by the sound source at the frequency sub-band associated with the weighting factor relative to all the other sub-bands within the overall frequency band,(g) identify the search direction exhibiting the maximum energy across the overall frequency band, and(h) designate the maximum energy direction as the direction to the sound source.
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Abstract
A system and process for sound source localization (SSL) utilizing beamsteering is presented. The present invention provides for improved beamsteering with less drain on system resources while providing accurate, real time results. To accomplish this, the present SSL system and process rejects as much as possible extraneous audio frames and analyzes only those frames exhibiting a well defined sound source. In addition, the number of beams is reduced as much as possible to save on processing time, but a full scan of the working volume is still made with the beams. And finally, interpolation is used to increase the precision of the technique.
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Citations
21 Claims
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1. A system for finding the direction to a sound source from a microphone array in a prescribed search area, comprising:
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a microphone array having a plurality of audio sensors; a general purpose computing device; a computer-readable medium having computer-executable instructions, wherein the computing device is directed by the instructions of the computer-readable medium to, (a) package the signals produced by the array microphones into frames, (b) select the frames representing the earliest captured frame of each microphone signal which have not been previously processed, (c) subject the selected frames to a noise suppression procedure, (d) classify the frames based on whether they exhibit evidence of a significant sound source, (e) whenever it is found that the frames do not exhibit evidence of a significant sound source, repeat program modules (b) through (e) as appropriate, (f) whenever it is found that the frames do exhibit evidence of a significant sound source, compute a full spectrum energy comprising an energy value for each of a prescribed set of audio frequency sub-bands within an overall frequency band for a beam in each of a prescribed number of directions, wherein a beam represents a region surrounding a direction extending away from the microphone array wherein sounds originating within that region remain unaffected, while sounds originating outside that region are suppressed, and wherein the prescribed number of directions represent a set of search directions extending away from the microphone array which when a beam is associated with each of the search directions covers the entire search area without significant overlap between adjacent beams extending along those directions, and for each computed energy value, apply a weighting factor associated with the frequency sub-band of the computed energy value, from a set of weighting factors comprising one for each of said set of audio frequency sub-bands, to the computed energy value, wherein each weighting factor reflects an energy level which is expected to be exhibited by the sound source at the frequency sub-band associated with the weighting factor relative to all the other sub-bands within the overall frequency band, (g) identify the search direction exhibiting the maximum energy across the overall frequency band, and (h) designate the maximum energy direction as the direction to the sound source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A computer-readable medium having computer-executable instructions;
- for finding the direction to a sound source from a microphone array in a prescribed search area using a beamsteering approach, said computer-executable instructions comprising using a computer to perform the following process actions;
determining the minimum number of beams it would take to cover the entire search area without significant overlap; establishing a set of search directions extending away from the microphone array which equal said minimum number of beams and which are spaced equally from each other in such a way as to cover the entire search area while preventing any significant overlap between adjacent beams extending along those directions; estimating the audio energy within the beams associated with each of the set of search directions, said estimation comprising computing an energy estimate as wherein fs is a prescribed sampling frequency, dl is a search direction, f belongs to a prescribed set of audio frequencies and S(f) is a weight function associated with frequency f, and wherein S(f) ranges between 0 and 1 and reflects an energy level at frequency f which is expected to be exhibited by the sound source relative to all the other frequencies within said set of audio frequencies; identifying the search direction exhibiting the maximum energy; designating the maximum energy direction as the direction to the sound source. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
- for finding the direction to a sound source from a microphone array in a prescribed search area using a beamsteering approach, said computer-executable instructions comprising using a computer to perform the following process actions;
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21. A computer-readable medium having computer-executable instructions for finding the direction to a sound source from a microphone array in a prescribed search area, said computer-executable instructions comprising:
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determining the minimum number of beams it will take to cover the entire search area without significant overlap, wherein a beam represents a region surrounding a direction extending away from the microphone array wherein sound originating within that region remain unaffected, while sounds originating outside that region are suppressed; establishing a set of search directions extending away from the microphone array which equal the minimum number of beams and which are spaced equally from each other in such a way as to prevent any significant overlap between adjacent beams extending along those directions; estimating the audio energy within the beams associated with each of the set of search directions, said estimation comprising computing an energy estimate as wherein fs is a prescribed sampling frequency, dl is a search direction, f belongs to a prescribed set of audio frequencies and S(f) is a weight function associated with frequency f, and wherein S(f) ranges between 0 and 1 and reflects an energy level at frequency f which is expected to be exhibited by the sound source relative to all the other frequencies within said set of audio frequencies; identifying the search direction exhibiting the maximum energy; and designating the maximum energy direction as the direction to the sound source.
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Specification