# US 2020/0288244 A1 · Method for determining a response function of a noise cancellation enabled audio device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0288244 A1 - Document ID: US20200288244A1 - Status: Published application - Kind: A1 - Application number: 16/759,638 - Filed: 2018-10-23 - Published: 2020-09-10 - Earliest claimed: 2017-11-02 - Assignees: Ams AG - Applicants: ams AG - Inventors: Robert ALCOCK - Web page: https://patentgrep.com/patent/US20200288244A1 ## CPC - G10K 11/17813: {characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms} - H04R 3/04: for correcting frequency response - G10K 11/17873: {using a reference signal without an error signal, e.g. pure feedforward} - H04R 5/033: Headphones for stereophonic communication {(details thereof, e.g. relating to batteries, cables or control elements H04R1/10)} - H04R 5/04: Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} - G10K 2210/30232: Transfer functions, e.g. impulse response - G10K 2210/3055: Transfer function of the acoustic system - G10K 2210/3057: Variation of parameters to test for optimisation - H04R 2460/01: Hearing devices using active noise cancellation - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - 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 In a method for determining a response function of a noise cancellation enabled audio device, the audio device is placed onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture. A first and a second response function between an ambient sound source and a test microphone located within the ear canal representation are measured while parameters of a noise processor of the audio device are set to a proportional transfer function with respective first and second gain factors being different from each other. A model response function is determined based on the first and the second response function and on the first and the second gain factor. ## Claims ### Claim 1 A method for determining a response function of a noise cancellation enabled audio device, in particular headphone, the method comprising: placing the audio device onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture; measuring a first response function between an ambient sound source and a test microphone located within the ear canal representation while parameters of a noise processor of the audio device are set to a proportional transfer function with a first gain factor; measuring a second response function between the ambient sound source and the test microphone while parameters of the noise processor are set to a proportional transfer function with a second gain factor being different from the first gain factor; determining a model response function for the noise processor based on the first response function, the second response function and the first and the second gain factor. ### Claim 2 (depends on 1) The method according to claim 1, further comprising: determining an ambient-to-ear response function based on the first and/or the second response function; and determining an overall processor response function based on the first response function, the second response function and the first and the second gain factor; wherein the model response function is determined from the ambient-to-ear response function and the overall processor response function. ### Claim 3 (depends on 1) The method according to claim 1, wherein the model response function F is determined according to the formula F = a   1 - X  ( a   2 - a   1 ) Y - X , with a1 being the first gain factor, a2 being the second gain factor, X being the first response function and Y being the second response function. ### Claim 4 (depends on 1) The method according to claim 1, further comprising: measuring a third response function between the ambient sound source and the test microphone while parameters of the noise processor are set to a proportional transfer function with a third gain factor being different from the first gain factor and the second gain factor; wherein the model response function is determined based on the first, the second and the third response function, and the first, the second and the third gain factor. ### Claim 5 (depends on 4) The method according to claim 4, further comprising: determining an ambient-to-ear response function based on the first response function or on the first, the second and the third response function; and determining an overall processor response function based on the first, the second and the third response function and on the first, the second and the third gain factor; wherein the model response function is determined from the ambient-to-ear response function and the overall processor response function. ### Claim 6 (depends on 4) The method according to claim 4, wherein the model response function F is determined according to the formula F = a   1 - X  ( a   3 - a   2 ) Z - Y , with a1 being the first gain factor, a2 being the second gain factor, a3 being the third gain factor, X being the first response function, Y being the second response function and Z being the third response function. ### Claim 7 (depends on 5) The method according to claim 5, further comprising determining a leakage response function based on the first, the second and the third response function and on the first, the second and the third gain factor; wherein the overall processor response function is determined further based on the leakage response function. ### Claim 8 (depends on 1) The method according to claim 1, wherein the first gain factor equals zero. ### Claim 9 (depends on 8) The method according to claim 8, wherein the noise processor disabled and/or muted during measurement of first response function. ### Claim 10 A method for determining a response function of a noise cancellation enabled audio device, in particular headphone, the method comprising: placing the audio device onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture; measuring a first response function between an ambient sound source and a test microphone located within the ear canal representation while parameters of a noise processor of the audio device are set to a predefined transfer function in combination with a first gain factor; measuring a second response function between the ambient sound source and the test microphone while parameters of the noise processor are set to the predefined transfer function in combination with a second gain factor being different from the first gain factor; determining a model response function for the noise processor based on the predefined transfer function, the first response function, the second response function and the first and the second gain factor. ### Claim 11 (depends on 10) The method according to claim 10, further comprising: measuring a third response function between the ambient sound source and the test microphone while parameters of the noise processor are set to the predefined transfer function in combination with a third gain factor being different from the first gain factor and the second gain factor; wherein the model response function is determined based on the predefined transfer function, the first, the second and the third response function, and the first, the second and the third gain factor. ### Claim 12 (depends on 11) The method according to claim 11, wherein each of the response functions measured between the ambient sound source and the test microphone is measured without accessing any test point within the audio device. ### Claim 13 (depends on 11) The method according to claim 11, each of the response functions measured between the ambient sound source and the test microphone is measured without the audio device being disassembled during the respective measurements. ### Claim 14 (depends on 11) The method according to claim 11, wherein the audio device and the noise processor are enabled for feedforward noise cancellation. ### Claim 15 (depends on 11) The method according to claim 11 further comprising determining parameters of a filter function of the noise processor based on the model response function. ### Claim 16 (depends on 1) The method according to claim 1, wherein each of the response functions measured between the ambient sound source and the test microphone is measured without accessing any test point within the audio device. ### Claim 17 (depends on 1) The method according to claim 1, wherein each of the response functions measured between the ambient sound source and the test microphone is measured without the audio device being disassembled during the respective measurements. ### Claim 18 (depends on 1) The method according to claim 1, wherein the audio device and the noise processor are enabled for feedforward noise cancellation. ### Claim 19 (depends on 1) The method according to claim 1, further comprising determining parameters of a filter function of the noise processor based on the model response function.