# US 10,871,543 B2 · Direction of arrival estimation of acoustic-signals from acoustic source using sub-array selection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,543 B2 - Document ID: US10871543B2 - Status: Granted - Kind: B2 - Application number: 16/006,362 - Filed: 2018-06-12 - Published: 2019-12-12 - Granted: 2020-12-22 - Earliest claimed: 2018-06-12 - Assignees: Kaam LLC - Applicants: Kaam LLC. - Inventors: Tejaswini Dudyala; Srivally Munnangi; Senthil Kumar Mani - Web page: https://patentgrep.com/patent/US10871543B2 ## CPC - G01S 3/8083: {determining direction of source} - G01S 3/808: using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems - H04R 1/406: {microphones} - G01S 3/801: Details {(G01S3/82, G01S3/84, G01S3/86 take precedence)} - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - H04R 2201/401: 2D or 3D arrays of transducers - H04R 2201/405: Non-uniform arrays of transducers or a plurality of uniform arrays with different transducer spacing - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract A system that handles direction of arrival (DOA) estimation for acoustic signals using sub-array selection, identifies a plurality of microphone sub-arrays from the plurality of microphones in the microphone-array, selects a set of microphone sub-arrays from the plurality of microphone sub-arrays, and computes a relative time-delay for arrival of the acoustic signals between each pair of microphones of the selected set of microphone sub-arrays. The selection is based on a maximum distance between each pair of microphones of the identified plurality of microphone sub-arrays of the microphone-array. A first microphone sub-array is determined from the selected set of microphone sub-arrays and the DOA of the acoustic signals is estimated with reference to the determined first microphone sub-array. The estimation of the direction of arrival of the acoustic signals is based on the computed relative time-delay for the determined first microphone sub-array of the microphone-array. ## Claims ### Claim 1 A system for processing acoustic signals, comprising: a microphone-array comprising a plurality of microphones; and a signal processing apparatus comprising a plurality of circuits associated with the microphone-array, wherein the plurality of circuits is configured to: identify a plurality of microphone sub-arrays from the plurality of microphones in the microphone-array, wherein each microphone sub-array of the identified plurality of microphone sub-arrays comprises a pair of microphones spaced apart by a specific distance; select a set of microphone sub-arrays from the identified plurality of microphone sub-arrays of the microphone-array based on a maximum distance between each pair of microphones of the plurality of microphone sub-arrays of the microphone-array; compute a relative time-delay for an arrival of the acoustic signals between each pair of microphones of the selected set of microphone sub-arrays, wherein the relative time-delay corresponds to an estimated time-delay for the arrival of the acoustic signals between each pair of microphones of the selected set of microphone sub-arrays; determine a first microphone sub-array from the selected set of microphone sub-arrays based on a maximum time-delay from the computed relative time-delay for each of the selected set of microphone sub-arrays, wherein the determined first microphone sub-array is a desired microphone sub-array from the identified plurality of microphone sub-arrays in the microphone-array; and estimate a direction of arrival of the acoustic signals with reference to the determined first microphone sub-array, based on the computed relative time-delay for the arrival of the acoustic signals at the determined first microphone sub-array. ### Claim 2 (depends on 1) The system according to claim 1, wherein the direction of arrival of the acoustic signals with reference to the determined first microphone sub-array is estimated based on one or more parameters, and wherein the one or more parameters comprises a sampling frequency of the acoustic signals, a speed of the acoustic signals, the computed relative time-delay for the determined first microphone sub-array, and a radius associated with a planar arrangement of the microphone-array. ### Claim 3 (depends on 1) The system according to claim 1, wherein the direction of arrival of the acoustic signals is estimated in one of a frequency domain and a time domain. ### Claim 4 (depends on 1) The system according to claim 1, wherein the direction of arrival of the acoustic signals with reference to the determined first microphone sub-array is estimated based on a digital filter that processes the acoustic signals received at a first microphone and a second microphone of the determined first microphone sub-array. ### Claim 5 (depends on 4) The system according to claim 4, wherein the digital filter for the estimation of the direction of arrival of the acoustic signals is one of an infinite impulse response (IIR) filter or a finite impulse response (FIR) filter that processes the acoustic signals based on one of a cross-correlation, a Fast Fourier Transform (FFT), a Discrete Fourier Transform (DFT) of the acoustic signals received at the first microphone and the second microphone of the determined first microphone sub-array. ### Claim 6 (depends on 1) The system according to claim 1, wherein the plurality of circuits is further configured to determine the specific distance between the pair of microphones of the plurality of microphone sub-arrays of the microphone-array. ### Claim 7 (depends on 1) The system according to claim 1, wherein the plurality of microphones are arranged in the microphone-array in a regular convex polygon arrangement, and wherein each microphone in the microphone-array is arranged at vertices of the regular convex polygon. ### Claim 8 (depends on 1) The system according to claim 1, wherein the selection of the set of microphone sub-arrays from the microphone-array is further based on a planar arrangement of the set of microphone sub-arrays that bisect each other in the microphone-array. ### Claim 9 (depends on 1) The system according to claim 1, wherein the first microphone sub-array is determined from the selected set of microphone sub-arrays based on a maximum of the computed relative time-delay among the selected set of microphone sub-arrays. ### Claim 10 (depends on 1) The system according to claim 1, wherein the relative time-delay for the selected set of microphone sub-arrays is computed based on a cross-correlation of the acoustic signals received at two different microphones of the selected set of microphone sub-arrays. ### Claim 11 (depends on 1) The system according to claim 1, wherein the relative time-delay is computed for each selected microphone sub-array instead of computation of the relative time-delay for each microphone sub-array in the microphone-array. ### Claim 12 (depends on 1) The system according to claim 1, wherein the direction of arrival of the acoustic signals is same as a direction that corresponds to a location of a signal source of the acoustic signals. ### Claim 13 A method for processing acoustic signals, comprising: in a signal processing apparatus that comprises a plurality of circuits that are communicatively coupled to a microphone-array: identifying, by the plurality of circuits, a plurality of microphone sub-arrays from the plurality of microphones in the microphone-array, wherein each microphone sub-array of the identified plurality of microphone sub-arrays comprises a pair of microphones spaced apart by a specific distance; selecting, by the plurality of circuits, a set of microphone sub-arrays from the identified plurality of microphone sub-arrays of the microphone-array based on a maximum distance between each pair of microphones of the plurality of microphone sub-arrays of the microphone-array; computing, by the plurality of circuits, a relative time-delay for an arrival of the acoustic signals between each pair of microphones of the selected set of microphone sub-arrays, wherein the relative time-delay corresponds to an estimated time-delay for the arrival of the acoustic signals between each pair of microphones of the selected set of microphone sub-arrays; determining, by the plurality of circuits, a first microphone sub-array from the selected set of microphone sub-arrays based on a maximum time-delay from the computed relative time-delay for each of the selected set of microphone sub-arrays, wherein the determined first microphone sub-array is a desired microphone sub-array from the identified plurality of microphone sub-arrays in the microphone-array; and estimating, by the plurality of circuits, a direction of arrival of the acoustic signals with reference to the determined first microphone sub-array, based on the computed relative time-delay for the arrival of the acoustic signals at the determined first microphone sub-array. ### Claim 14 (depends on 13) The method according to claim 13, wherein the direction of arrival of the acoustic signals with reference to the determined first microphone sub-array is estimated based on one or more parameters, and wherein the one or more parameters comprises a sampling frequency of the acoustic signals, a speed of the acoustic signals, the computed relative time-delay for the determined first microphone sub-array, and a radius associated with a planar arrangement of the microphone-array. ### Claim 15 (depends on 13) The method according to claim 13, wherein the direction of arrival of the acoustic signals is estimated in one of a frequency domain and a time domain. ### Claim 16 (depends on 13) The method according to claim 13, further comprising determining, by the plurality of circuits, the specific distance between the pair of microphones of the plurality of microphone sub-arrays of the microphone-array. ### Claim 17 (depends on 13) The method according to claim 13, wherein the plurality of microphones are arranged in the microphone-array in a regular convex polygon arrangement, and wherein each microphone in the microphone-array is arranged at vertices of the regular convex polygon. ### Claim 18 (depends on 13) The method according to claim 13, wherein the selection of the set of microphone sub-arrays from the microphone-array is further based on a planar arrangement of the set of microphone sub-arrays that bisect each other in the microphone-array. ### Claim 19 (depends on 13) The method according to claim 13, wherein the first microphone sub-array is determined from the selected set of microphone sub-arrays based on a maximum of the computed relative time-delay among the selected set of microphone sub-arrays. ### Claim 20 (depends on 13) The method according to claim 13, wherein the relative time-delay for the selected set of microphone sub-arrays is computed based on a cross-correlation of the acoustic signals received at two different microphones of the selected set of microphone sub-arrays.