# US 10,873,810 B2 · Sound pickup device and sound pickup method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,810 B2 - Document ID: US10873810B2 - Status: Granted - Kind: B2 - Application number: 16/572,825 - Filed: 2019-09-17 - Published: 2020-01-09 - Granted: 2020-12-22 - Earliest claimed: 2017-03-24 - Assignees: Yamaha Corporation - Applicants: Yamaha Corporation - Inventors: Tetsuto Kawai; Mikio Muramatsu; Takayuki Inoue; Satoshi Ukai - Web page: https://patentgrep.com/patent/US10873810B2 ## CPC - H04R 3/04: for correcting frequency response - G10L 21/0208: Noise filtering - G10L 21/0264: characterised by the type of parameter measurement, e.g. correlation techniques, zero crossing techniques or predictive techniques - H04R 1/08: Mouthpieces; {Microphones;} Attachments therefor - H04R 1/40: by combining a number of identical transducers {(specially adapted for hearing aids H04R25/405)} - H04R 1/406: {microphones} - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - H04R 29/004: {for microphones (H04R29/007 takes precedence)} - H04R 2201/40: Details of arrangements for obtaining desired directional characteristic by combining a number of identical transducers covered by H04R1/40 but not provided for in any of its subgroups - 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) - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING ## Abstract A sound pickup method obtains a correlation between a first sound pickup signal to be generated from a first microphone and a second sound pickup signal to be generated from a second microphone, and performs level control of the first sound pickup signal or the second sound pickup signal, according to a ratio of a frequency component of which the correlation exceeds a threshold value. ## Claims ### Claim 1 A sound pickup device comprising: a calculator that: obtains a first sound pickup signal to be generated from a first sound signal output by a first microphone and a second sound pickup signal to be generated from a second sound signal output by a second microphone; converts the first sound pickup signal and the second sound pickup signal into a first frequency signal and a second frequency signal; calculates a coherence between the first frequency signal and the second frequency signal; and calculates a ratio of a frequency component of which the calculated coherence exceeds a first threshold value with respect to all frequency components; and a level controller that controls a level of the first sound pickup signal or the second sound pickup signal according to the calculated ratio. ### Claim 2 (depends on 1) The sound pickup device according to claim 1, further comprising: the first microphone; and the second microphone. ### Claim 3 (depends on 1) The sound pickup device according to claim 1, wherein the level controller determines whether or not the calculated coherence exceeds the first threshold value for each frequency component, obtains the calculated ratio by totaling the number of frequency components that exceeds the first threshold value with respect to the all frequency components. ### Claim 4 (depends on 1) The sound pickup device according to claim 1, wherein the level controller includes a directivity former that generates the first sound pickup signal and the second sound pickup signal from the first sound signal output by the first microphone and the second sound signal output by the second microphone. ### Claim 5 (depends on 4) The sound pickup device according to claim 4, wherein: the first microphone and the second microphone are directional microphones, and the directivity former generates the first sound pickup signal having directivity, and the second sound pickup signal having non-directivity, from the first and second signals output by the first microphone and the second microphone. ### Claim 6 (depends on 4) The sound pickup device according to claim 4, wherein the directivity former generates the first sound pickup signal or the second sound pickup signal by obtaining a sum of delays of the first and second sound signals output by the first microphone and the second microphone. ### Claim 7 (depends on 1) The sound pickup device according to claim 1, wherein the level controller estimates a noise component, and reduces the estimated noise component from the first sound pickup signal or the second sound pickup signal to control the level thereof. ### Claim 8 (depends on 7) The sound pickup device according to claim 7, wherein the level controller, according to the calculated ratio, turns on or off the noise component reduction. ### Claim 9 (depends on 1) The sound pickup device according to claim 1, wherein the level controller includes a comb filter that reduces a harmonic component based on sound. ### Claim 10 (depends on 9) The sound pickup device according to claim 9, wherein the level controller, according to the calculated ratio, turns on or off processing by the comb filter. ### Claim 11 (depends on 1) The sound pickup device according to claim 1, wherein the level controller includes a gain controller that controls a gain of the first sound pickup signal or the second sound pickup signal. ### Claim 12 (depends on 11) The sound pickup device according to claim 11, wherein the level controller attenuates the gain according to the calculated ratio in a case where the calculated ratio is less than a second threshold value. ### Claim 13 (depends on 12) The sound pickup device according to claim 12, wherein the second threshold value is determined based on the calculated ratio calculated within a predetermined time. ### Claim 14 (depends on 11) The sound pickup device according to claim 11, wherein the level controller sets the gain as a minimum gain in a case where the calculated ratio is less than a second threshold value. ### Claim 15 A sound pickup method comprising: obtaining a correlation between a first sound pickup signal to be generated from a first sound signal output by a first microphone and a second sound pickup signal to be generated from a second sound signal output by a second microphone; and converting the first sound pickup signal and the second sound pickup signal into a first frequency signal and a second frequency signal; calculating a coherence between the first frequency signal and the second frequency signal; calculating a ratio of a frequency component of which the calculated coherence exceeds a first threshold value with respect to all frequency components; and controlling a level of the first sound pickup signal or the second sound pickup signal according to the calculated ratio. ### Claim 16 (depends on 15) The sound pickup method according to claim 15, further comprising determining whether or not the calculated coherence exceeds the first threshold value for each frequency component, obtaining the calculated ratio by totaling the number of frequency components that exceeds the first threshold value with respect to the all frequency components. ### Claim 17 (depends on 15) The sound pickup method according to claim 15, further comprising generating the first sound pickup signal and the second sound pickup signal from the first sound signal output by the first microphone and the second sound signal output by the second microphone. ### Claim 18 (depends on 17) The sound pickup method according to claim 17, wherein the generating generates the first sound pickup signal having directivity, and the second sound pickup signal having non-directivity, from the first and second signals output by the first microphone and the second microphone. ### Claim 19 A sound pickup device comprising: at least one memory device that stores instructions; and at least one processor that executes the instructions to: obtains a first sound pickup signal to be generated from a first sound signal output by a first microphone and a second sound pickup signal to be generated from a second sound signal output by a second microphone; converts the first sound pickup signal and the second sound pickup signal into a first frequency signal and a second frequency signal; calculates a coherence between the first frequency signal and the second frequency signal; calculates a ratio of a frequency component of which the calculated coherence exceeds a threshold value with respect to all frequency components; and controls a level of the first sound pickup signal or the second sound pickup signal according to the calculated ratio.