Microphone array subset selection for robust noise reduction
First Claim
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1. A method of processing a multichannel signal, the method being implemented by an audio sensing device, said method comprising:
- for each of a plurality of different frequency components of the multichannel signal, calculating a difference between a phase of the frequency component at a first time in each of a first pair of channels of the multichannel signal, to obtain a first plurality of phase differences;
based on information from the first plurality of phase differences, calculating a value of a first coherency measure that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the first pair of channels of the multichannel signal at the first time are coherent in a first spatial sector;
for each of the plurality of different frequency components of the multichannel signal, calculating a difference between a phase of the frequency component at a second time in each of a second pair of channels of the multichannel signal, said second pair of channels of the multichannel signal being different than said first pair of channels of the multichannel signal, to obtain a second plurality of phase differences;
based on information from the second plurality of phase differences, calculating a value of a second coherency measure that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the second pair of channels of the multichannel signal at the second time are coherent in a second spatial sector;
calculating a contrast of the first coherency measure by evaluating a relation between the calculated value of the first coherency measure and an average value of the first coherency measure over time;
calculating a contrast of the second coherency measure by evaluating a relation between the calculated value of the second coherency measure and an average value of the second coherency measure over time; and
based on which is greatest between the contrast of the first coherency measure and the contrast of the second coherency measure, selecting one between the first and second pairs of channels of the multichannel signal,wherein said multichannel signal is received via a microphone array.
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Abstract
A disclosed method selects a plurality of fewer than all of the channels of a multichannel signal, based on information relating to the direction of arrival of at least one frequency component of the multichannel signal.
29 Citations
40 Claims
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1. A method of processing a multichannel signal, the method being implemented by an audio sensing device, said method comprising:
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for each of a plurality of different frequency components of the multichannel signal, calculating a difference between a phase of the frequency component at a first time in each of a first pair of channels of the multichannel signal, to obtain a first plurality of phase differences; based on information from the first plurality of phase differences, calculating a value of a first coherency measure that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the first pair of channels of the multichannel signal at the first time are coherent in a first spatial sector; for each of the plurality of different frequency components of the multichannel signal, calculating a difference between a phase of the frequency component at a second time in each of a second pair of channels of the multichannel signal, said second pair of channels of the multichannel signal being different than said first pair of channels of the multichannel signal, to obtain a second plurality of phase differences; based on information from the second plurality of phase differences, calculating a value of a second coherency measure that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the second pair of channels of the multichannel signal at the second time are coherent in a second spatial sector; calculating a contrast of the first coherency measure by evaluating a relation between the calculated value of the first coherency measure and an average value of the first coherency measure over time; calculating a contrast of the second coherency measure by evaluating a relation between the calculated value of the second coherency measure and an average value of the second coherency measure over time; and based on which is greatest between the contrast of the first coherency measure and the contrast of the second coherency measure, selecting one between the first and second pairs of channels of the multichannel signal, wherein said multichannel signal is received via a microphone array. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for processing a multichannel signal, said apparatus comprising:
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means for calculating, for each of a plurality of different frequency components of the multichannel signal, a difference between a phase of the frequency component at a first time in each of a first pair of channels of the multichannel signal, to obtain a first plurality of phase differences; means for calculating a value of a first coherency measure, based on information from the first plurality of phase differences, that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the first pair of channels of the multichannel signal at the first time are coherent in a first spatial sector; means for calculating, for each of the plurality of different frequency components of the multichannel signal, a difference between a phase of the frequency component at a second time in each of a second pair of channels of the multichannel signal, said second pair of channels of the multichannel signal being different than said first pair of channels of the multichannel signal, to obtain a second plurality of phase differences; means for calculating a value of a second coherency measure, based on information from the second plurality of phase differences, that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the second pair of channels of the multichannel signal at the second time are coherent in a second spatial sector; means for calculating a contrast of the first coherency measure by evaluating a relation between the calculated value of the first coherency measure and an average value of the first coherency measure over time; means for calculating a contrast of the second coherency measure by evaluating a relation between the calculated value of the second coherency measure and an average value of the second coherency measure over time; and means for selecting one between the first and second pairs of channels of the multichannel signal, based on which is greatest between the contrast of the first coherency measure and the contrast of the second coherency measure, wherein at least one among said means for calculating a difference at a first time, said means for calculating a value of a first coherency measure, said means for calculating a difference at a second time, said means for calculating a value of a second coherency measure, said means for calculating a contrast of the first coherency measure, said means for calculating a contrast of the second coherency measure, and said means for selecting is implemented by at least one processor, and wherein said multichannel signal is received via a microphone array. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. An apparatus for processing a multichannel signal, said apparatus comprising:
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a first calculator configured to calculate, for each of a plurality of different frequency components of the multichannel signal, a difference between a phase of the frequency component at a first time in each of a first pair of channels of the multichannel signal, to obtain a first plurality of phase differences; a second calculator configured to calculate a value of a first coherency measure, based on information from the first plurality of phase differences, that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the first pair of channels of the multichannel signal at the first time are coherent in a first spatial sector; a third calculator configured to calculate, for each of the plurality of different frequency components of the multichannel signal, a difference between a phase of the frequency component at a second time in each of a second pair of channels of the multichannel signal, said second pair of channels of the multichannel signal being different than said first pair of channels of the multichannel signal, to obtain a second plurality of phase differences; a fourth calculator configured to calculate a value of a second coherency measure, based on information from the second plurality of phase differences, that indicates a degree to which directions of arrival of at least the plurality of different frequency components of the second pair of channels of the multichannel signal at the second time are coherent in a second spatial sector; a fifth calculator configured to calculate a contrast of the first coherency measure by evaluating a relation between the calculated value of the first coherency measure and an average value of the first coherency measure over time; a sixth calculator configured to calculate a contrast of the second coherency measure by evaluating a relation between the calculated value of the second coherency measure and an average value of the second coherency measure over time; and a selector configured to select one between the first and second pairs of channels, based on which is greatest between the contrast of the first coherency measure and the contrast of the second coherency measure, wherein at least one among said first calculator, said second calculator, said third calculator, said fourth calculator, said fifth calculator, said sixth calculator, and said selector is implemented by at least one processor, and wherein said multichannel signal is received via a microphone array. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method of processing a multichannel signal, the method being implemented by an audio sensing device, said method comprising:
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for a first pair of channels of the multichannel signal, calculating a value of a first coherency measure that indicates a degree to which directions of arrival of different frequency components of the first pair of channels of the multichannel signal are coherent; for a second pair of channels of the multichannel signal that is different than said first pair of channels of the multichannel signal, calculating a value of a second coherency measure that indicates a degree to which directions of arrival of different frequency components of the second pair of channels of the multichannel signal are coherent; calculating a contrast of the first coherency measure by evaluating a relation between the calculated value of the first coherency measure and an average value of the first coherency measure over time; calculating a contrast of the second coherency measure by evaluating a relation between the calculated value of the second coherency measure and an average value of the second coherency measure over time; and based on which is greatest between the contrast of the first coherency measure and the contrast of the second coherency measure, selecting one between the first and second pairs of channels of the multichannel signal, wherein said multichannel signal is received via a microphone array. - View Dependent Claims (37, 38, 39, 40)
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Specification