Acoustic source localization system and method
First Claim
1. A method of forming information for determining a direction of an acoustic source using at least three spaced-apart microphones, the microphones coupling acoustic signals from at least two pairs of microphones with each pair of microphones receiving two acoustic signals and having a separation distance and an orientation of its two microphones, the method comprising:
- for each pair of microphones, calculating a plurality of sample elements for the two acoustic signals received by the pair of microphones, the plurality of sample elements corresponding to a ranking of possible time delays between the two acoustic signals received by the pair of microphones with each sample element having a time delay and a numeric sample value;
for the plurality of sample elements of each pair of microphones, mapping each sample element to a sub-surface of potential acoustic source locations according to its time delay and the orientation and the separation distance of the pair of microphones for which the sample element was calculated, and assigning the sub-surface the sample value of the sample element, producing a plurality of sub-surfaces for each pair of microphones;
for a boundary surface intersecting each of the plurality of sub-surfaces, the boundary surface divisible into a plurality of cells, calculating a weighted value in each cell of the boundary surface by combining the sample values of the plurality of sub-surfaces proximal the cell to form a weighted surface with the weighted value of each cell of the weighted surface being indicative of the likelihood that the acoustic source lies in a direction of a bearing vector passing through the cell.
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Accused Products
Abstract
An acoustic source location technique compares the time response of signals from two or more pairs of microphones. For each pair of microphones, a plurality of sample elements are calculated that correspond to a ranking of possible time delay offsets for the two acoustic signals received by the pair of microphones, with each sample element having a delay time and a sample value. Each sample element is mapped to a sub-surface of potential acoustic source locations and assigned the sample value. A weighted value is calculated on each cell of a common boundary surface by combining the values of the plurality of sub-surfaces proximate the cell to form a weighted surface with the weighted value assigned to each cell interpreted as being indicative that a bearing vector to the acoustic source passes through the cell.
121 Citations
40 Claims
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1. A method of forming information for determining a direction of an acoustic source using at least three spaced-apart microphones, the microphones coupling acoustic signals from at least two pairs of microphones with each pair of microphones receiving two acoustic signals and having a separation distance and an orientation of its two microphones, the method comprising:
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for each pair of microphones, calculating a plurality of sample elements for the two acoustic signals received by the pair of microphones, the plurality of sample elements corresponding to a ranking of possible time delays between the two acoustic signals received by the pair of microphones with each sample element having a time delay and a numeric sample value;
for the plurality of sample elements of each pair of microphones, mapping each sample element to a sub-surface of potential acoustic source locations according to its time delay and the orientation and the separation distance of the pair of microphones for which the sample element was calculated, and assigning the sub-surface the sample value of the sample element, producing a plurality of sub-surfaces for each pair of microphones;
for a boundary surface intersecting each of the plurality of sub-surfaces, the boundary surface divisible into a plurality of cells, calculating a weighted value in each cell of the boundary surface by combining the sample values of the plurality of sub-surfaces proximal the cell to form a weighted surface with the weighted value of each cell of the weighted surface being indicative of the likelihood that the acoustic source lies in a direction of a bearing vector passing through the cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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19. A method of forming information for determining the location of an acoustic source using at least three spaced-apart microphones, the microphones coupling acoustic signals from at least two pairs of microphones with each pair of microphones receiving two acoustic signals and having a separation distance and an orientation of its microphones, the method comprising:
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for each pair of microphones, cross-correlating the two acoustic signals received by the pair of microphones to produce a plurality of sample elements with each sample element having a time delay and a sample value;
for each sample element of the plurality of sample elements associated with each pair of microphones, mapping the sample element to a cone of potential acoustic source locations appropriate for the time delay of the sample element and the separation distance and the orientation of the pair of microphones for which the sample element was calculated and assigning the cone the sample value of the sample element, forming a sequence of cones for each pair of microphones;
for each pair of microphones, mapping the sequence of cones associated with the pair of microphones to a boundary surface divisible into a plurality of cells and interpolating the sample values between adjacent cones to form a continuous acoustic location function on the boundary surface having a resampled value in each cell, thereby forming a plurality of acoustic location functions; and
in each cell, combining the resampled value of each of the acoustic location functions to form a weighted acoustic location function having a weighted value in each cell indicative of the likelihood that the acoustic source lies in a direction of a bearing vector passing through the cell.
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31. A method of forming information for determining the location of an acoustic source using at least three spaced-apart microphones, the microphones coupling signals from at least two pairs of microphones with each pair of microphones receiving two acoustic signals and having a separation distance and an orientation of its microphones, the method comprising:
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for each pair of microphones, cross-correlating the two acoustic signals received by the pair of microphones to produce a sequence of discrete sample elements for the pair of microphones with each sample element having a time delay and a sample value;
for each pair of microphones, mapping each sample element of its sequence of sample elements to a cone of potential acoustic source locations appropriate for the time delay of the sample element and the orientation and separation distance of the pair of microphones for which the sample element was calculated, and assigning the cone the sample value, thereby forming for each pair of microphones a sequence of cones;
for each pair of microphones, mapping its sequence of cones to a hemisphere divisible into a plurality of cells and interpolating sample values between adjacent cones to form for each pair of microphones an acoustic location function having a resampled value on each cell of the hemisphere; and
forming a weighted acoustic location function having a weighted value in each cell by combining in each cell the resampled values of each of the acoustic location functions, the weighted value of each cell being indicative of the likelihood that the acoustic source lies in a direction of a bearing vector passing through the cell. - View Dependent Claims (32, 33, 34, 36, 37, 38)
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35. A system for generating data regarding the location of an acoustic source, comprising:
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at least three microphones coupled to provide acoustic signals from at least two pairs of microphones with each pair of microphones consisting of two microphones receiving two acoustic signals and having a separation distance and an orientation;
an analog-to-digital converter adapted to sample the acoustic signals at a preselected rate and to convert the acoustic signals into digital representations of the acoustic signals;
a correlation module receiving the digital representations of the acoustic signals and outputting for each pair of microphones a sequence of discrete sample elements with each sample element having a time delay and a sample value; and
an acoustic source direction module receiving the sample elements configured to form a weighted acoustic location function on a boundary surface, the acoustic source direction module comprising;
a mapping sub-module mapping each sample element to a cone of potential acoustic source locations appropriate for the time delay of the sample element and the separation distance and the orientation of the pair of microphones for which the sample element was calcualted and assigning each cone the sample value;
a resampling sub-module adapted to interpolate the sample values between adjacent cones of each pair of microphones on the boundary surface, the resampling module forming an acoustic location function for each pair of microphones that has a resampled value on each cell of the boundary surface; and
a combining sub-module configured to combine the resampled values of the acoustic location function on each cell into a weighted value for the cell that is indicative of the likelihood that the acoustic source lies along in the direction of a bearing vector passing through the cell.
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39. A system for generating data regarding the location of an acoustic source, comprising:
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a plurality of pairs of microphones;
correlation means for producing for each pair of microphones a sequence of discrete sample elements with each sample element having a time delay and a sample value; and
acoustic source direction means receiving the sample elements and calculating a weighted value on each of a plurality of cells of a common boundary surface, the weighted value on each cell being indicative of the likelihood that the acoustic source lies in a bearing direction passing through the cell.
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40. A computer program product for forming information for determining a direction to an acoustic source from the acoustic signals of at least three microphones coupled to provide acoustic signals from at least two pairs of microphones with each pair of microphones consisting of two microphones receiving two acoustic signals and having a separation distance and an orientation, the computer program product comprising:
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a computer readable medium;
a cross-correlation module stored on the computer readable medium, and configured to receive a digital representation of the acoustic signals and outputting for each pair of microphones a sequence of sample elements with each sample element having a time delay and a sample value; and
an acoustic source direction module stored on the computer readable medium, and configured to receive the sample elements and perform the steps of;
for the plurality of sample elements of each pair of microphones, mapping each sample element to a sub-surface of potential acoustic source locations according to its time delay and the orientation and the separation distance of the two microphones of the pair of microphones for which the sample element was calculated, and assigning to the sub-surface the numeric sample value of the sample element, producing a plurality of sub-surfaces for each pair of microphones; and
calculating for a boundary surface intersecting each of the plurality of sub-surfaces and divisible into a plurality of cells, a weighted value in each cell of the boundary surface by combining the values of the plurality of sub-surfaces proximal the cell to form a weighted surface with the weighted value of each cell of the weighted surface being indicative of the likelihood that the acoustic source lies in a direction of a bearing vector passing through the cell.
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Specification