# US 12,192,739 B2 · Interpolation of finite impulse response filters for generating sound fields > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,192,739 B2 - Document ID: US12192739B2 - Status: Granted - Kind: B2 - Application number: 17/964,543 - Filed: 2022-10-12 - Published: 2024-04-18 - Granted: 2025-01-07 - Earliest claimed: 2022-10-12 - Assignees: Harman International Industries, Incorporated - Applicants: Harman International Industries, Incorporated - Inventors: Alfredo Fernandez Franco - Web page: https://patentgrep.com/patent/US12192739B2 ## CPC - H04S 7/301: {Automatic calibration of stereophonic sound system, e.g. with test microphone} - H04S 7/303: {Tracking of listener position or orientation} - H04R 3/04: for correcting frequency response - H04S: STEREOPHONIC SYSTEMS - 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 Various embodiments disclose a computer-implemented method comprising determining a target location in an environment, determining a set of sub-band impulse responses for a first frequency sub-band, each in the set of sub-band impulse responses being associated with a location proximate to the target location, selecting a first pair of sub-band impulse responses for the first frequency sub-band among pairs within the set of sub-band impulse responses, computing a first coherence value indicating a coherence level between sub-band impulse responses in the first pair, determining that the first coherence value is below a coherence threshold, in response, combining the sub-band impulse responses using a non-linear interpolation technique to generate an estimated impulse response for the first frequency sub-band for the target location, generating, based on the estimated impulse response, a filter for a speaker, filtering an audio signal, and causing the speaker to output the filtered audio signal. ## Claims ### Claim 1 A computer-implemented method comprising: determining a target location in an environment; determining a set of sub-band impulse responses for a first frequency sub-band, each sub-band impulse response in the set of sub-band impulse responses being associated with a corresponding location that is proximate to the target location; selecting a first pair of sub-band impulse responses for the first frequency sub-band from among pairs of sub-band impulse responses in the set of sub-band impulse responses; computing a first coherence value indicating a level of coherence between sub-band impulse responses in the first pair; determining that the first coherence value is below a coherence threshold; in response to determining that the first coherence value is below the coherence threshold, combining the sub-band impulse responses in the first pair using a non-linear interpolation technique to generate an estimated impulse response for the first frequency sub-band for the target location; generating, based at least on the estimated impulse response, a filter for a speaker; filtering, by the filter, an audio signal to generate a filtered audio signal; and causing the speaker to output the filtered audio signal. ### Claim 2 (depends on 1) The computer-implemented method of claim 1, wherein the corresponding location of each of the sub-band impulse responses in the set of sub-band impulse responses is within a threshold distance of the target location, and wherein the threshold distance is one of a Euclidean distance or a perceived audio distance. ### Claim 3 (depends on 1) The computer-implemented method of claim 1, wherein selecting the first pair of sub-band impulse responses comprises: computing, for each pair of impulse responses in the set of sub-band impulse responses, a corresponding coherence value between the impulse responses in the pair; and selecting, as the first pair, the pair of impulse responses having a highest coherence value. ### Claim 4 (depends on 1) The computer-implemented method of claim 1, wherein the non-linear interpolation technique is selected from a group consisting of: nearest-neighbor interpolation, a Lagrange interpolation, a least-squares interpolation, a bicubic spline interpolation, a cosine interpolation, and a parabolic interpolation. ### Claim 5 (depends on 1) The computer-implemented method of claim 1, further comprising: determining, a second set of sub-band impulse responses for a second frequency sub-band, each sub-band impulse response in the second set of sub-band impulse responses corresponding to a sub-band impulse response in the second set of sub-band impulse responses; selecting a second pair of sub-band impulse responses for the second frequency sub-band from among pairs of sub-band impulse responses in the second set of sub-band impulse responses; computing a second coherence value indicating a level of coherence between sub-band impulse responses in the second pair; and determining whether the second coherence value is equal to or above the coherence threshold. ### Claim 6 (depends on 5) The computer-implemented method of claim 5, further comprising: in response to determining that the second coherence value is equal to or above the coherence threshold, combining the sub-band impulse responses in the second pair using a linear interpolation technique to generate a second estimated impulse response for the second frequency sub-band for the target location; or in response to determining that the second coherence value is below the coherence threshold, combining the sub-band impulse responses in the second pair using the non-linear interpolation technique to generate the second estimated impulse response for the second frequency sub-band for the target location, wherein the filter is further based on the second estimated impulse response. ### Claim 7 (depends on 1) The computer-implemented method of claim 1, wherein determining the set of sub-band impulse responses comprises: decomposing each impulse response in a set of impulse responses into a plurality of sub-band impulse responses, wherein each sub-band impulse response in the plurality of sub-band impulse responses is associated with a different frequency range; and grouping, from each impulse response in the set of impulse responses, the sub-band impulse response for the first frequency sub-band to generate the set of sub-band impulse responses for the first frequency sub-band. ### Claim 8 (depends on 1) The computer-implemented method of claim 1, wherein the target location is based on a location of a listener within the environment. ### Claim 9 (depends on 8) The computer-implemented method of claim 8, further comprising: determining a second target location in the environment, wherein the second target location corresponds to a second listener within the environment; determining a second set of sub-band impulse responses for the first frequency sub-band, each sub-band impulse response in the second set of sub-band impulse responses being associated with a corresponding location that is proximate to the second target location; generating, based on the second set of impulse responses, a second estimated impulse response for the second target location; and generating, based at least on the second estimated impulse response, a second filter for the speaker. ### Claim 10 (depends on 1) The computer-implemented method of claim 1, further comprising: determining an updated target location in the environment; determining a second set of sub-band impulse responses for the first frequency sub-band, each sub-band impulse response in the second set of sub-band impulse responses being associated with a corresponding location that is proximate to the updated target location; generating an updated estimated impulse response based on the second set of impulse responses; and updating, based on the updated estimated impulse response, the filter for the speaker. ### Claim 11 One or more non-transitory computer-readable media comprising instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of: determining a target location in an environment; determining a set of sub-band impulse responses for a first frequency sub-band, each sub-band impulse response in the set of sub-band impulse responses being associated with a corresponding location that is proximate to the target location; selecting a first pair of sub-band impulse responses for the first frequency sub-band from among pairs of sub-band impulse responses in the set of sub-band impulse responses; computing a first coherence value indicating a level of coherence between sub-band impulse responses in the first pair; determining that the first coherence value is below a coherence threshold; in response to determining that the first coherence value is below the coherence threshold, combining the sub-band impulse responses in the first pair using a non-linear interpolation technique to generate an estimated impulse response for the first frequency sub-band for the target location; generating, based at least on the estimated impulse response, a filter for a speaker; filtering, by the filter, an audio signal to generate a filtered audio signal; and causing the speaker to output the filtered audio signal. ### Claim 12 (depends on 11) The one or more non-transitory computer-readable media of claim 11, wherein the corresponding location of each of the sub-band impulse responses in the set of sub-band impulse responses is within a threshold distance of the target location, and wherein the threshold distance is one of a Euclidean distance or a perceived audio distance. ### Claim 13 (depends on 11) The one or more non-transitory computer-readable media of claim 11, wherein: the corresponding location of each of the sub-band impulse responses in the set of sub-band impulse responses is located a corresponding distance from the target location, the corresponding distance is one of a Euclidean distance or a perceived audio distance; and determining the set of sub-band impulse responses comprises selecting a predetermined number of the sub-band impulse responses whose corresponding distances are shortest. ### Claim 14 (depends on 11) The one or more non-transitory computer-readable media of claim 11, wherein selecting the first pair of sub-band impulse responses comprises: computing, for each pair of impulse responses in the set of sub-band impulse responses, a corresponding coherence value between the impulse responses in the pair; and selecting, as the first pair, the pair of impulse responses having a highest coherence value. ### Claim 15 (depends on 11) The one or more non-transitory computer-readable media of claim 11, the steps further comprising: determining, a second set of sub-band impulse responses for a second frequency sub-band, each sub-band impulse response in the second set of sub-band impulse responses corresponding to a sub-band impulse response in the second set of sub-band impulse responses; selecting a second pair of sub-band impulse responses for the second frequency sub-band from among pairs of sub-band impulse responses in the second set of sub-band impulse responses; computing a second coherence value indicating a level of coherence between sub-band impulse responses in the second pair; determining whether the second coherence value is equal to or above the coherence threshold; and in response to determining that the second coherence value is equal to or above the coherence threshold, combining the sub-band impulse responses in the second pair using a linear interpolation technique to generate a second estimated impulse response for the second frequency sub-band for the target location; or in response to determining that the second coherence value is below the coherence threshold, combining the sub-band impulse responses in the second pair using the non-linear interpolation technique to generate the second estimated impulse response for the second frequency sub-band for the target location, wherein the filter is further based on the second estimated impulse response. ### Claim 16 (depends on 11) The one or more non-transitory computer-readable media of claim 11, wherein the target location is based on a location of a listener within the environment. ### Claim 17 A system comprising: a memory storing instructions; and a processor coupled to the memory that executes the instructions to perform steps comprising: determining a target location in an environment; determining a set of sub-band impulse responses for a first frequency sub-band, each sub-band impulse response in the set of sub-band impulse responses being associated with a corresponding location that is proximate to the target location; selecting a first pair of sub-band impulse responses for the first frequency sub-band from among pairs of sub-band impulse responses in the set of sub-band impulse responses; computing a first coherence value indicating a level of coherence between sub-band impulse responses in the first pair; determining that the first coherence value is below a coherence threshold; in response to determining that the first coherence value is below the coherence threshold, combining the sub-band impulse responses in the first pair using a non-linear interpolation technique to generate an estimated impulse response for the first frequency sub-band for the target location; generating, based at least on the estimated impulse response, a filter for a speaker; filtering, by the filter, an audio signal to generate a filtered audio signal; and causing the speaker to output the filtered audio signal. ### Claim 18 (depends on 17) The system of claim 17, wherein selecting the first pair of sub-band impulse responses comprises: computing, for each pair of impulse responses in the set of sub-band impulse responses, a corresponding coherence value between the impulse responses in the pair; and selecting, as the first pair, the pair of impulse responses having a highest coherence value. ### Claim 19 (depends on 17) The system of claim 17, further comprising a sensor; wherein the steps further comprise: acquiring, using the sensor, sensor data associated within a listener within the environment; and determining the target location based on the sensor data. ### Claim 20 (depends on 17) The system of claim 17, wherein the filter comprises a filter bank including distinct filters for separate frequency bands.