# US 12,604,137 B2 · Beamformed microphone array > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,604,137 B2 - Document ID: US12604137B2 - Status: Granted - Kind: B2 - Application number: 18/247,433 - Filed: 2021-09-30 - Published: 2024-01-04 - Granted: 2026-04-14 - Earliest claimed: 2020-10-01 - Assignees: Dotterel Technologies Limited - Applicants: Dotterel Technologies Limited - Inventors: Shaun Taggart Pentecost; Samuel Seamus Rowe; Shaun Edlin; Matthew Rowe; Hin Loh; Mark Poletti - Web page: https://patentgrep.com/patent/US12604137B2 ## CPC - G10L 21/0208: Noise filtering - H04R 1/40: by combining a number of identical transducers {(specially adapted for hearing aids H04R25/405)} - H04R 1/32: for obtaining desired directional characteristic only {(specially adapted for hearing aids H04R25/40)} - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - G10L 2021/02166: {Microphone arrays; Beamforming} - H04R 29/00: Monitoring arrangements; Testing arrangements {(for hearing aids H04R25/30; detection of loudspeaker connection H04R5/04; sound-field adaptation dependent on speaker detection H04S7/308)} - H04R 2201/003: Mems transducers or their use - H04R 2201/403: Linear arrays of transducers - H04R 2430/20: Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence) - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - 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 According to a first aspect of the invention, there is provided a method of beamforming for a linear microphone array comprising: storing a desired end-fire beam response including a beamwidth specification; determining an error data set from the stored end-fire beam response; and determining beamforming weights based on a least squares minimisation of the error data set. There are also provided a system, a microphone array, and an apparatus. ## Claims ### Claim 1 A method of beamforming for a plurality of linear microphone arrays within a three-dimensional housing, comprising: storing a desired end-fire beam response including a beamwidth specification; determining and storing diffraction behaviors around a microphone array of the plurality of linear microphone arrays; compensating for the diffraction behaviors by including a diffraction compensation factor; determining an error data set from the stored end-fire beam response and the diffraction compensation factor; and determining beamforming weights based on a least squares minimization of the error data set. ### Claim 2 (depends on 1) The method of claim 1, further comprising weighting the error data set. ### Claim 3 (depends on 1) The method of claim 1, further comprising regularizing the least squares minimization of the error data set. ### Claim 4 (depends on 1) The method of claim 1, further comprising an inverse Fourier transformation and a convolution operation. ### Claim 5 (depends on 1) The method of claim 1, wherein the beamforming weights low-pass filter the response of a first microphone of the microphone array with a first cut-off frequency and low-pass filter the response of a second microphone of the microphone array with a second cut-off frequency different from the first cut-off frequency, wherein the microphone array has a center, the first microphone is closer to the center than the second microphone, and the first cut-off frequency is higher than the second cut-off frequency. ### Claim 6 (depends on 1) The method of claim 1, wherein the beamwidth of an end-fire beam beamformed using the determined beamforming weights varies by no more than 50% across the frequency range of 2000 Hz to 16000 Hz. ### Claim 7 (depends on 1) The method of claim 1, wherein the stored desired end-fire beam response is part of a noise-filtering algorithm and is a first main beam, further comprising storing a second beam response including a beamwidth specification different from the beamwidth specification of the stored desired end-fire beam response, wherein the second beam response is also part of the noise-filtering algorithm and is also an end-fire main beam. ### Claim 8 (depends on 1) The method of claim 1, wherein the stored desired end-fire beam response is part of a noise-filtering algorithm and is a first null beam, further comprising storing a second beam response including a beamwidth specification different from the beamwidth specification of the stored desired end-fire beam response, wherein the second beam response is also part of the noise-filtering algorithm and is also a null beam. ### Claim 9 (depends on 1) The method of claim 1, further comprising compensating for diffraction behaviors of the physical microphone array structure. ### Claim 10 (depends on 1) A non-transitory computer readable medium having stored thereon software instructions that, when executed by a processing unit, cause the processing unit to perform the method of claim 1. ### Claim 11 (depends on 1) A system, comprising: a processing unit; and a microphone array comprising a plurality of linear microphone arrays within a three-dimensional housing; wherein the processing unit is configured to receive audio from the plurality of linear microphone arrays and apply the method of beamforming of claim 1 to the received audio to generate an end-fire beam. ### Claim 12 (depends on 11) The system of claim 11, wherein the processing unit is in the same physical package as the microphone array. ### Claim 13 (depends on 11) The system of claim 11, wherein the processing unit is a ground station. ### Claim 14 (depends on 11) The system of claim 11, wherein the processing unit is configured to sum outputs of one or more microphones of the plurality of linear microphone arrays. ### Claim 15 (depends on 11) The system of claim 11, wherein the processing unit is configured to beamform multiple beams, and wherein a second beam of the multiple beams is wider than the end-fire beam. ### Claim 16 (depends on 15) The system of claim 15, wherein the end-fire beam is more sensitive than the second beam to the position of a target audio source, and the second beam is more sensitive than the end-fire beam to the position of a noise source. ### Claim 17 (depends on 16) The system of claim 16, wherein the processing unit is further configured to execute a noise-filtering algorithm that uses the second beam to reduce the power of any noise signal of the noise source captured by the end-fire beam, and wherein the end-fire beam is an end-fire main beam. ### Claim 18 (depends on 11) The system of claim 11, further comprising a plurality of filters, each filter is configured to receive a respective output signal from a respective linear microphone array of the plurality of linear microphone arrays, each filter is configured to have at least one associated coefficient or constant, and wherein a plurality of filtered signals output from each of the plurality of filters are configured to be combined into a smaller subset of beamformer outputs; and a user beamformer selection input configured to receive a user selection, and depending on the selection to adjust the coefficient or constant associated with each filter to achieve a desired smaller subset of beamformer outputs and/or resulting beamforming pattern. ### Claim 19 (depends on 18) The system of claim 18, further comprising a control housing; a data connection between the microphone housing and the control housing; a processor within the control housing or the microphone housing configured to form an end-fire beam response from the outputs of the plurality of linear microphone arrays; and one or more user input devices on the control housing configured to adjust the end-fire beam. ### Claim 20 (depends on 19) The system of claim 19, further comprising an output providing an end-fire beam response from the smaller subset of beamformer outputs, wherein the sidelobe response of the output is considerably lower than an interference tube shotgun mic.