# US 12,192,711 B2 · Speaker calibration method, apparatus and program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,192,711 B2 - Document ID: US12192711B2 - Status: Granted - Kind: B2 - Application number: 17/921,555 - Filed: 2020-06-04 - Published: 2023-06-01 - Granted: 2025-01-07 - Earliest claimed: 2020-06-04 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Kazunori Kobayashi; Ryotaro Sato - Web page: https://patentgrep.com/patent/US12192711B2 ## CPC - H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)} - H04S 7/301: {Automatic calibration of stereophonic sound system, e.g. with test microphone} - H04R 1/403: {loud-speakers} - 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 2430/20: Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence) - 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) - H04S: STEREOPHONIC SYSTEMS ## Abstract There are included a first speaker processing step in which a first speaker 2 produces sound based on a first filtered signal, a gain multiplication step in which a gain multiplication unit 4 generates a gain multiplied signal by multiplying a second filtered signal by a gain, a second speaker processing step in which a second speaker 5 produces sound based on the gain multiplied signal, and a gain control step in which a gain control unit 7 controls the gain such that a root mean square of a collected sound signal collected by a microphone 6 installed at a mute position, which is a position at which the sound produced by the first speaker and the sound produced by the second speaker are to be muted, is relatively small. ## Claims ### Claim 1 A method for speaker calibration, comprising: a first filter processing step in which a first filtered signal is generated by filtering an input signal; a first speaker processing step in which sound based on the first filtered signal is produced by a first speaker; a second filter processing step in which a second filtered signal is generated by filtering the input signal; a gain multiplication step in which a gain multiplied signal is generated by multiplying the second filtered signal by a gain; a second speaker processing step in which sound based on the gain multiplied signal is produced by a second speaker; and a gain control step in which the gain is controlled such that a root mean square of a collected sound signal collected by a microphone installed at a mute position is smaller than a root mean square of the collected sound without gain control, the mute position being a position at which the sound produced by the first speaker and the sound produced by the second speaker are to be muted. ### Claim 2 (depends on 1) The method for speaker calibration according to claim 1, further comprising: a first low-pass filter processing step in which a first low-pass filtered signal is generated by low-pass filtering the second filtered signal; and a second low-pass filter processing step in which a second low-pass filtered signal is generated by low-pass filtering the collected sound signal, wherein the gain is controlled by using the first low-pass filtered signal and the second low-pass filtered signal such that a root mean square of the second low-pass filtered signal is smaller than a root mean square of the collected sound without gain control. ### Claim 3 (depends on 1) The method for speaker calibration according to claim 1, further comprising: a delay step in which the second filtered signal is delayed. ### Claim 4 (depends on 1) The method for speaker calibration according to claim 1, further comprising: a first band division step in which the second filtered signal is divided into a plurality of bands; and a second band division step in which the collected sound signal is divided into a plurality of bands, wherein corresponding operations are performed for individual signal divisions obtained by dividing the second filtered signal under the plurality of bands or individual signal divisions obtained by dividing the collected sound signal under the plurality of bands in the gain multiplication step, the gain control step, the first low-pass filter processing step, the second low-pass filter processing step, and the delay step, the method further comprising: a band combination step in which multiplied signals generated for the respective bands are combined together, wherein the second speaker produces sound based on the combined signals. ### Claim 5 (depends on 1) A non-transitory computer readable medium that stores a program causing a computer to perform operations of the steps of the method for speaker calibration according to claim 1. ### Claim 6 A device for speaker calibration, comprising: processing circuitry; a first speaker; a second speaker; and a microphone, wherein the processing circuitry is configured to generate a first filtered signal by filtering an input signal; the first speaker is configured to produce sound based on the first filtered signal; the processing circuitry is configured to generate a second filtered signal by filtering the input signal; the processing circuitry is configured to generate a gain multiplied signal by multiplying the second filtered signal by a gain; the second speaker is configured to produce sound based on the gain multiplied signal; the microphone is installed at a mute position at which the sound produced by the first speaker and the sound produced by the second speaker are to be muted; and the processing circuitry is configured to control gain such that a root mean square of a collected sound signal collected by the microphone is smaller than a root mean square of the collected sound without gain control.