# US 12,015,902 B2 · Echo cancellation device, echo cancellation method, and program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,902 B2 - Document ID: US12015902B2 - Status: Granted - Kind: B2 - Application number: 17/632,852 - Filed: 2019-08-06 - Published: 2022-10-13 - Granted: 2024-06-18 - Earliest claimed: 2019-08-06 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Masahiro Fukui - Web page: https://patentgrep.com/patent/US12015902B2 ## CPC - H04R 3/02: for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)} - H04R 2430/03: Synergistic effects of band splitting and sub-band processing - 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 Provided is an echo cancellation apparatus capable of calculating an acoustic coupling amount with high accuracy regardless of the magnitude of the near-end speaker component and without using a double talk detector. The echo cancellation apparatus cancels an echo included in a sound pickup signal picked up by a microphone placed at a near-end and includes an acoustic coupling amount calculation unit that updates and calculates an acoustic coupling amount estimated value of a component of a reproduction signal, which is a signal picked up by a microphone placed at a far-end included in the sound pickup signal, such that an update amount is decreased the greater a magnitude of a component other than an echo component is in the sound pickup signal; a gain calculation unit that calculates a gain coefficient on the basis of the acoustic coupling amount estimated value; and an integration unit that integrates the gain coefficient with the sound pickup signal and generates an echo cancellation signal. ## Claims ### Claim 1 An echo cancellation apparatus for cancelling an echo included in a sound pickup signal picked up by a microphone placed at a near-end, the apparatus comprises a processor configured to execute operations comprising: calculating an acoustic coupling amount estimated value of a component of a reproduction signal, wherein the reproduction signal represents a sound signal picked up by a microphone placed at a far-end, and the calculating further comprises updating the acoustic coupling amount estimated value with a smaller amount as an update amount, as a magnitude of a component of the sound pickup signal other than an echo component of the sound pickup signal increases; calculating a gain coefficient on the basis of the acoustic coupling amount estimated value; and generating, based on integrating the gain coefficient with the sound pickup signal, an echo cancellation signal. ### Claim 2 (depends on 1) The echo cancellation apparatus according to claim 1, wherein the calculating an acoustic coupling amount estimated value further comprises determining the update amount by controlling a step size in a case where a formula for obtaining the acoustic coupling amount estimated value is represented by an updated formula with the step size. ### Claim 3 (depends on 2) The echo cancellation apparatus according claim 2, wherein the acoustic coupling amount estimated value is calculated via ❘ "\[LeftBracketingBar]" H ~ m , i ( ω ) ❘ "\[RightBracketingBar]" 2 = ❘ "\[LeftBracketingBar]" μ i - m , ω σ [ S ^ i ( ω ) ] · Y i ( ω ) X i - m ( ω ) + ( 1 - μ i - m , ω σ [ S ^ i ( ω ) ] ) ⁢ H ~ m , i - 1 ( ω ) ❘ "\[RightBracketingBar]" 2 where, i is a frame number, m is a frame corresponding to an impulse response length of an echo path, ω is a frequency value, μ is the step size, S{circumflex over ( )}(ω) is an echo cancellation signal spectrum, σ[S{circumflex over ( )}(ω)] is a parameter that takes a value that increases as a magnitude of a component other than an echo component included in a frame of a current time increases, Y(ω) is a sound pickup signal spectrum, X(ω) is a reproduction signal spectrum, and |H˜(ω)|2 is the acoustic coupling amount estimated value. ### Claim 4 (depends on 1) The echo cancellation apparatus according to claim 1, wherein the calculating acoustic coupling amount estimated value further comprises: decreasing the update amount of the acoustic coupling amount as a proportion of the component of the sound pickup signal other than the echo component increases when determining an amount to update of the acoustic coupling amount only in a case where a proportion of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold and an average value of a frequency component of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold, and determining an update amount of the acoustic coupling amount without using a proportion of the component of the sound pickup signal other than the echo component in a case where a proportion of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold or in a case where an average value of a frequency component of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold. ### Claim 5 An echo cancellation method for cancelling an echo included in a sound pickup signal picked up by a microphone placed at a near-end, comprising: calculating an acoustic coupling amount estimated value of a component of a reproduction signal, wherein the reproduction signal represents a sound signal picked up by a microphone placed at a far-end, and the calculating further comprises updating the acoustic coupling amount estimated value with a smaller amount as an update amount, as a magnitude of a component of the sound pickup signal other than an echo component is of the sound pickup signal increases; calculating a gain coefficient on the basis of the acoustic coupling amount estimated value; and generating, based on integrating the gain coefficient with the sound pickup signal, an echo cancellation signal. ### Claim 6 (depends on 2) The echo cancellation apparatus according to claim 2, wherein the calculating an acoustic coupling amount estimated value further comprises: decreasing the update amount of the acoustic coupling amount as a proportion of the component of the sound pickup signal other than the echo component increases when determining an amount to update of the acoustic coupling amount only in a case where a proportion of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold and an average value of a frequency component of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold, and determining the update amount of the acoustic coupling amount without using a proportion of the component of the sound pickup signal other than the echo component in a case where a proportion of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold or in a case where an average value of a frequency component of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold. ### Claim 7 (depends on 3) The echo cancellation apparatus according to claim 3, wherein the calculating an acoustic coupling amount estimated value further comprises: decreasing the update amount of the acoustic coupling amount as a proportion of the component of the sound pickup signal other than the echo component increases when determining an amount to update of the acoustic coupling amount only in a case where a proportion of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold and an average value of a frequency component of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold, and determining an update amount of the acoustic coupling amount without using a proportion of the component of the sound pickup signal other than the echo component in a case where a proportion of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold or in a case where an average value of a frequency component of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold. ### Claim 8 A system for cancelling an echo included in a sound pickup signal picked up by a microphone placed at a near-end comprising: a processor; and a memory storing computer-executable instructions that when executed by the processor cause the system to perform a method, the method comprising: calculating an acoustic coupling amount estimated value of a component of a reproduction signal, wherein the reproduction signal represents a sound signal picked up by a microphone placed at a far-end, and the calculating further comprises updating the acoustic coupling amount estimated value with a smaller amount as an update amount, as a magnitude of a component of the sound pickup signal other than an echo component is in the sound pickup signal increases; calculating a gain coefficient on the basis of the acoustic coupling amount estimated value; and generating, based on integrating the gain coefficient with the sound pickup signal, an echo cancellation signal. ### Claim 9 (depends on 8) The system according to claim 8 wherein the calculating an acoustic coupling amount estimated value further comprises determining the update amount by controlling a step size in a case where a formula for obtaining the acoustic coupling amount estimated value is represented by an updated formula with the step size. ### Claim 10 (depends on 9) The system according to claim 9, wherein the acoustic coupling amount estimated value is calculated via ❘ "\[LeftBracketingBar]" H ~ m , i ( ω ) ❘ "\[RightBracketingBar]" 2 = ❘ "\[LeftBracketingBar]" μ i - m , ω σ [ S ^ i ( ω ) ] · Y i ( ω ) X i - m ( ω ) + ( 1 - μ i - m , ω σ [ S ^ i ( ω ) ] ) ⁢ H ~ m , i - 1 ( ω ) ❘ "\[RightBracketingBar]" 2 where, i is a frame number, m is a frame corresponding to an impulse response length of an echo path, ω is a frequency value, μ is the step size, S{circumflex over ( )}(ω) is an echo cancellation signal spectrum, α[S{circumflex over ( )}(ω)] is a parameter that takes a value that increases as a magnitude of a component other than an echo component included in a frame of a current time increases, Y(ω) is a sound pickup signal spectrum, X(ω) is a reproduction signal spectrum, and |H˜(ω)|2 is the acoustic coupling amount estimated value. ### Claim 11 (depends on 8) The system according to claim 8, wherein the calculating an acoustic coupling amount estimated value further comprises: decreasing the update amount of the acoustic coupling amount as a proportion of the component other than the echo component increases when determining an amount to update of the acoustic coupling amount only in a case where a proportion of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold and an average value of a frequency component of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold, and determining an update amount of the acoustic coupling amount without using a proportion of the component of the sound pickup signal other than the echo component in a case where a proportion of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold or in a case where an average value of a frequency component of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold. ### Claim 12 (depends on 9) The system according to claim 9, wherein the calculating an acoustic coupling amount estimated value further comprises: decreasing the update amount of the acoustic coupling amount as a proportion of the component of the sound pickup signal other than the echo component increases when determining an amount to update of the acoustic coupling amount only in a case where a proportion of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold and an average value of a frequency component of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold, and determining the update amount of the acoustic coupling amount without using a proportion of the component of the sound pickup signal other than the echo component in a case where a proportion of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold or in a case where an average value of a frequency component of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold. ### Claim 13 (depends on 10) The system according to claim 10, wherein the calculating an acoustic coupling amount estimated value further comprises: decreasing the update amount of the acoustic coupling amount as a proportion of the component of the sound pickup signal other than the echo component increases when determining an amount to update of the acoustic coupling amount only in a case where a proportion of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold and an average value of a frequency component of the component of the sound pickup signal other than the echo component is greater than a predetermined threshold, and determining the update amount of the acoustic coupling amount without using a proportion of the component of the sound pickup signal other than the echo component in a case where a proportion of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold or in a case where an average value of a frequency component of the component of the sound pickup signal other than the echo component is equal to or less than a predetermined threshold.