Microphone system and a hearing device comprising a microphone system
First Claim
1. A microphone system adapted to be worn at an ear of a user, the microphone system comprisinga multitude of M of microphones, where M is larger than or equal to two, adapted for picking up sound from the environment and to provide M corresponding electric input signals xm(n), m=1, . . . , M, n representing time, the environment sound at a given microphone comprising a mixture of a target sound signal sm(n) propagated via an acoustic propagation channel from a location of a target sound source, and possible additive noise signals vm(n) as present at the location of the microphone in question;
- a signal processor connected to said number of microphones, and being configured to estimate a direction- to and/or a position of the target sound source relative to the microphone system based ona maximum likelihood methodology, anda database Θ
comprising a dictionary of vectors dθ
, termed RTF-vectors, whose elements are relative transfer functions dm(k) representing direction-dependent acoustic transfer functions from said target signal source to each of said M microphones (m=1, . . . , M) relative to a reference microphone (m=i) among said M microphones, k being a frequency index, whereinindividual dictionary elements of said database Θ
of RTF vectors dθ
comprises relative transfer functions for a number of different directions (θ
) and/or positions (θ
, φ
, r) relative to the microphone system;
the signal processor is configured todetermine a posterior probability or a log (posterior) probability of some of or all of said individual dictionary elements, anddetermine one or more of the most likely directions to or locations of said target sound source by determining the one or more values among said determined posterior probabilities or said log (posterior) probabilities having the largest posterior probability(ies) or log (posterior) probability(ies), respectively; and
said relative transfer functions dm(k) of the database Θ
represent direction-dependent filtering effects of the head and torso of the user in the form of direction-dependent acoustic transfer functions from said target signal source to each of said M microphones (m=1, . . . , M) relative to a reference microphone (m=i) among said M microphones.
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Abstract
A microphone system comprises a multitude of microphones; a signal processor connected to said number of microphones, and being configured to estimate a direction- to and/or a position of the target sound source relative to the microphone system based on a maximum likelihood methodology; and a database Θ comprising a dictionary of relative transfer functions representing direction-dependent acoustic transfer functions from said target signal source to each of said microphones relative to a reference microphone among said microphones, wherein individual dictionary elements of said database Θ of relative transfer functions comprises relative transfer functions for a number of different directions and/or positions relative to the microphone system; and wherein the signal processor is configured to determine one or more of the most likely directions to or locations of said target sound source. The invention may e.g. be used for the hearing aids or other portable audio communication devices.
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Citations
23 Claims
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1. A microphone system adapted to be worn at an ear of a user, the microphone system comprising
a multitude of M of microphones, where M is larger than or equal to two, adapted for picking up sound from the environment and to provide M corresponding electric input signals xm(n), m=1, . . . , M, n representing time, the environment sound at a given microphone comprising a mixture of a target sound signal sm(n) propagated via an acoustic propagation channel from a location of a target sound source, and possible additive noise signals vm(n) as present at the location of the microphone in question; -
a signal processor connected to said number of microphones, and being configured to estimate a direction- to and/or a position of the target sound source relative to the microphone system based on a maximum likelihood methodology, and a database Θ
comprising a dictionary of vectors dθ
, termed RTF-vectors, whose elements are relative transfer functions dm(k) representing direction-dependent acoustic transfer functions from said target signal source to each of said M microphones (m=1, . . . , M) relative to a reference microphone (m=i) among said M microphones, k being a frequency index, whereinindividual dictionary elements of said database Θ
of RTF vectors dθ
comprises relative transfer functions for a number of different directions (θ
) and/or positions (θ
, φ
, r) relative to the microphone system;the signal processor is configured to determine a posterior probability or a log (posterior) probability of some of or all of said individual dictionary elements, and determine one or more of the most likely directions to or locations of said target sound source by determining the one or more values among said determined posterior probabilities or said log (posterior) probabilities having the largest posterior probability(ies) or log (posterior) probability(ies), respectively; and said relative transfer functions dm(k) of the database Θ
represent direction-dependent filtering effects of the head and torso of the user in the form of direction-dependent acoustic transfer functions from said target signal source to each of said M microphones (m=1, . . . , M) relative to a reference microphone (m=i) among said M microphones. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 13)
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10. A microphone system comprising:
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a multitude of M of microphones, where M is larger than or equal to two, adapted for picking up sound from the environment and to provide M corresponding electric input signals xm(n), m=1, . . . , M, n representing time, the environment sound at a given microphone comprising a mixture of a target sound signal sm(n) propagated via an acoustic propagation channel from a location of a target sound source, and possible additive noise signals vm(n) as present at the location of the microphone in question; a signal processor connected to said number of microphones, and being configured to estimate a direction- to and/or a position of the target sound source relative to the microphone system based on a maximum likelihood methodology; a database Θ
comprising a dictionary of vectors dθ
, termed RTF-vectors, whose elements are relative transfer functions dm(k) representing direction-dependent acoustic transfer functions from said target signal source to each of said M microphones (m=1, . . . , M) relative to a reference microphone (m=i) among said M microphones, k being a frequency index, whereinindividual dictionary elements of said database Θ
of RTF vectors dθ
comprises relative transfer functions for a number of different directions (θ
) and/or positions (θ
, φ
, r) relative to the microphone system; and
the signal processor is configured todetermine a posterior probability or a log (posterior) probability of some of or all of said individual dictionary elements, and determine one or more of the most likely directions to or locations of said target sound source by determining the one or more values among said determined posterior probabilities or said log (posterior) probabilities having the largest posterior probability(ies) or log (posterior) probability(ies), respectively; and the signal processor is configured to utilize information not derived from said electric input signals to determine one or more of the most likely directions to or locations of said target sound source. - View Dependent Claims (11, 12)
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14. A hearing device adapted for being won at or in an ear of a user, or for being fully or partially implanted in the head at an ear of the user, the hearing device comprising;
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a microphone system comprising a multitude of M of microphones, where M is larger than or equal to two, adapted for picking up sound from the environment and to provide M corresponding electric input signals xm(n), m=1, . . . , M, n representing time, the environment sound at a given microphone comprising a mixture of a target sound signal sm(n) propagated via an acoustic propagation channel from a location of a target sound source, and possible additive noise signals vm(n) as present at the location of the microphone in question; a signal processor connected to said number of microphones, and being configured to estimate a direction- to and/or a position of the target sound source relative to the microphone system based on a maximum likelihood methodology, and a database Θ
comprising a dictionary of vectors dθ
, termed RTF-vectors, whose elements are relative transfer functions dm(k) representing direction-dependent acoustic transfer functions from said target signal source to each of said M microphones (m=1, . . . , M) relative to a reference microphone (m=i) among said M microphones, k being a frequency index, whereinindividual dictionary elements of said database Θ
of RTF vectors dθ
comprises relative transfer functions for a number of different directions (θ
) and/or positions (θ
, φ
, r) relative to the microphone system; andthe signal processor is configured to determine a posterior probability or a log (posterior) probability of some of or all of said individual dictionary elements, and determine one or more of the most likely directions to or locations of said target sound source by determining the one or more values among said determined posterior probabilities or said log (posterior) probabilities having the largest posterior probability(ies) or log (posterior) probability(ies), respectively; and a beamformer filtering unit operationally connected to at least some of said multitude of microphones and configured to receive said electric input signals, and configured to provide a beamformed signal in dependence of said one or more of the most likely directions to or locations of said target sound source estimated by said signal processor. - View Dependent Claims (15, 16, 17, 18)
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19. A method of operating a microphone system comprising a multitude of M of microphones, where M is larger than or equal to two, adapted for picking up sound from the environment, the method comprising:
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providing M electric input signals xm(n), m=1, . . . , M, n representing time, each electric input signal representing the environment sound at a given microphone and comprising a mixture of a target sound signal sm(n) propagated via an acoustic propagation channel from a location of a target sound source, and possible additive noise signals vm(n) as present at the location of the microphone in question; estimating a direction- to and/or a position of the target sound source relative to the microphone system based on said electric input signals; a maximum likelihood methodology; and a database Θ
comprising a dictionary of relative transfer functions dm(k) representing direction-dependent acoustic transfer functions from each of said M microphones (m=1, . . . , M) to a reference microphone (m=i) among said M microphones, k being a frequency index, whereinthe method further comprises providing that individual dictionary elements of said database Θ
of relative transfer functions dm(k) comprises relative transfer functions for a number of different directions (θ
) and/or positions (θ
, φ
, r) relative to the microphone system, where θ
, φ
, and r are spherical coordinates; anddetermining a posterior probability or a log (posterior) probability of some of or all of said individual dictionary elements, determining one or more of the most likely directions to or locations of said target sound source by determining the one or more values among said determined posterior probability or said log (posterior) probability having the largest posterior probability(ies) or log (posterior) probability(ies), respectively, and reducing computational complexity in determining one or more of the most likely directions to or locations of said target sound source by one or more of dynamically down sampling, selecting a subset of the number of dictionary elements, selecting a subset of the number of frequency channels, and removing terms in the likelihood function with low importance. - View Dependent Claims (20, 21, 22, 23)
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Specification