# US 2021/0241783 A1 · Two-dimensional smoothing of post-filter masks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0241783 A1 - Document ID: US20210241783A1 - Status: Published application - Kind: A1 - Application number: 16/779,946 - Filed: 2020-02-03 - Published: 2021-08-05 - Earliest claimed: 2020-02-03 - Assignees: Bose Corporation - Applicants: Bose Corporation - Inventors: Ankita D. Jain; Cristian Marius Hera; Elie Bou Daher - Web page: https://patentgrep.com/patent/US20210241783A1 ## CPC - G10L 21/0232: Processing in the frequency domain - H04R 3/02: for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)} - G10L 21/0208: Noise filtering - G10L 21/0224: Processing in the time domain - G10L 21/0272: Voice signal separating - G10L 2021/02168: {the estimation exclusively taking place during speech pauses} - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - H04R 3/12: for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)} - H04R 2499/13: Acoustic transducers and sound field adaptation in vehicles - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - 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 A method includes receiving multiple samples of time-domain data that includes noise, computing a first two-dimensional (2D) time-frequency representation of the time domain data, and processing the first time-frequency representation using a time-frequency noise reduction mask to generate a second, noise-reduced time-frequency representation of the time domain data. The method also includes generating a time domain output based on the noise-reduced time-frequency representation. ## Claims ### Claim 1 A method comprising: receiving multiple samples of time-domain data that includes noise; computing a first two-dimensional (2D) time-frequency representation of the time domain data; processing the first time-frequency representation using a time-frequency noise reduction mask to generate a second, noise-reduced time-frequency representation of the time domain data, wherein generating the time-frequency noise reduction mask for a particular time-frequency bin comprises: determining an initial value of the mask as a function of a ratio of (i) an estimated power spectral density of the noise corresponding to the particular time-frequency bin, and (ii) an estimated power spectral density of a measured signal corresponding to the particular time-frequency bin, and updating the initial value of the mask to generate an updated value of the mask, wherein the updating is performed based on initial or updated values of one or more additional masks corresponding to time-frequency bins different from the particular time-frequency bin; and generating a time domain output based on the noise-reduced time-frequency representation. ### Claim 2 (depends on 1) The method of claim 1, wherein updating the initial value of the mask comprises: determining a time-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the time axis of the 2D time-frequency representation, wherein the time smoothing parameter is a function of the initial or updated values of multiple masks corresponding to different time points; and generating the updated value of the mask as a function of the time-smoothing parameter. ### Claim 3 (depends on 1) The method of claim 1, wherein updating the initial value of the mask comprises: determining a frequency-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the frequency axis of the 2D time-frequency representation, wherein the frequency smoothing parameter represents a variable number of time-frequency bins along the frequency axis that are used in updating the initial value; and generating the updated value of the mask as a function of the frequency-smoothing parameter. ### Claim 4 (depends on 3) The method of claim 3, further comprising: receiving input on an upper limit of a frequency range for frequency smoothing; and determining the number of time-frequency bins along the frequency axis that are used in updating the initial value as a function of the upper limit of a frequency range. ### Claim 5 (depends on 1) The method of claim 1, wherein updating the initial value of the mask comprises: determining a time-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the time axis of the 2D time-frequency representation determining a frequency-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the frequency axis of the 2D time-frequency representation; and generating the updated value of the mask as a function of the time-smoothing parameter and the frequency-smoothing parameter. ### Claim 6 (depends on 5) The method of claim 5, wherein: the time smoothing parameter is a function of the initial or updated values of multiple masks corresponding to different time points, and the frequency smoothing parameter represents a variable number of time-frequency bins along the frequency axis that are used in updating the initial value. ### Claim 7 (depends on 6) The method of claim 6, further comprising: receiving input on an upper limit of a frequency range for frequency smoothing; and determining the number of time-frequency bins along the frequency axis that are used in updating the initial value as a function of the upper limit of a frequency range. ### Claim 8 A system comprising: A noise analysis engine including one or more processing devices, the noise analysis engine configured to: receive multiple samples of time-domain data that includes noise, compute a first two-dimensional (2D) time-frequency representation of the time domain data, and process the first time-frequency representation using a time-frequency noise reduction mask to generate a second, noise-reduced time-frequency representation of the time domain data, wherein generating the time-frequency noise reduction mask for a particular time-frequency bin comprises: determining an initial value of the mask as a function of a ratio of (i) an estimated power spectral density of the noise corresponding to the particular time-frequency bin, and (ii) an estimated power spectral density of a measured signal corresponding to the particular time-frequency bin, and updating the initial value of the mask to generate an updated value of the mask, wherein the updating is performed based on initial or updated values of one or more additional masks corresponding to time-frequency bins different from the particular time-frequency bin; and a reconstruction engine that generates a time domain output based on the noise-reduced time-frequency representation. ### Claim 9 (depends on 8) The system of claim 8, wherein updating the initial value of the mask comprises: determining a time-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the time axis of the 2D time-frequency representation, wherein the time smoothing parameter is a function of the initial or updated values of multiple masks corresponding to different time points; and generating the updated value of the mask as a function of the time-smoothing parameter. ### Claim 10 (depends on 8) The system of claim 8, wherein updating the initial value of the mask comprises: determining a frequency-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the frequency axis of the 2D time-frequency representation, wherein the frequency smoothing parameter represents a variable number of time-frequency bins along the frequency axis that are used in updating the initial value; and generating the updated value of the mask as a function of the frequency-smoothing parameter. ### Claim 11 (depends on 10) The system of claim 10, wherein the noise analysis engine is configured to: receive input on an upper limit of a frequency range for frequency smoothing; and determine the number of time-frequency bins along the frequency axis that are used in updating the initial value as a function of the upper limit of a frequency range. ### Claim 12 (depends on 8) The system of claim 8, wherein updating the initial value of the mask comprises: determining a time-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the time axis of the 2D time-frequency representation determining a frequency-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the frequency axis of the 2D time-frequency representation; and generating the updated value of the mask as a function of the time-smoothing parameter and the frequency-smoothing parameter. ### Claim 13 (depends on 12) The system of claim 12, wherein: the time smoothing parameter is a function of the initial or updated values of multiple masks corresponding to different time points, and the frequency smoothing parameter represents a variable number of time-frequency bins along the frequency axis that are used in updating the initial value. ### Claim 14 (depends on 13) The system of claim 13, wherein the noise analysis engine is configured to: receive input on an upper limit of a frequency range for frequency smoothing; and determine the number of time-frequency bins along the frequency axis that are used in updating the initial value as a function of the upper limit of a frequency range. ### Claim 15 One or more non-transitory machine-readable storage devices storing machine-readable instructions that cause one or more processing devices to execute operations comprising: receiving multiple samples of time-domain data that includes noise; computing a first two-dimensional (2D) time-frequency representation of the time domain data; processing the first time-frequency representation using a time-frequency noise reduction mask to generate a second, noise-reduced time-frequency representation of the time domain data, wherein generating the time-frequency noise reduction mask for a particular time-frequency bin comprises: determining an initial value of the mask as a function of a ratio of (i) an estimated power spectral density of the noise corresponding to the particular time-frequency bin, and (ii) an estimated power spectral density of a measured signal corresponding to the particular time-frequency bin, and updating the initial value of the mask to generate an updated value of the mask, wherein the updating is performed based on initial or updated values of one or more additional masks corresponding to time-frequency bins different from the particular time-frequency bin; and generating a time domain output based on the noise-reduced time-frequency representation. ### Claim 16 (depends on 15) The one or more non-transitory machine-readable storage devices of claim 15, wherein updating the initial value of the mask comprises: determining a time-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the time axis of the 2D time-frequency representation, wherein the time smoothing parameter is a function of the initial or updated values of multiple masks corresponding to different time points; and generating the updated value of the mask as a function of the time-smoothing parameter. ### Claim 17 (depends on 15) The one or more non-transitory machine-readable storage devices of claim 15, wherein updating the initial value of the mask comprises: determining a frequency-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the frequency axis of the 2D time-frequency representation, wherein the frequency smoothing parameter represents a variable number of time-frequency bins along the frequency axis that are used in updating the initial value; and generating the updated value of the mask as a function of the frequency-smoothing parameter. ### Claim 18 (depends on 17) The one or more non-transitory machine-readable storage devices of claim 17, the operations further comprising: receiving input on an upper limit of a frequency range for frequency smoothing; and determining the number of time-frequency bins along the frequency axis that are used in updating the initial value as a function of the upper limit of a frequency range. ### Claim 19 (depends on 15) The one or more non-transitory machine-readable storage devices of claim 15, wherein updating the initial value of the mask comprises: determining a time-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the time axis of the 2D time-frequency representation determining a frequency-smoothing parameter for updating the initial value as a function of the initial or updated values of one or more additional masks corresponding to time-frequency bins along the frequency axis of the 2D time-frequency representation; and generating the updated value of the mask as a function of the time-smoothing parameter and the frequency-smoothing parameter. ### Claim 20 (depends on 19) The one or more non-transitory machine-readable storage devices of claim 19, wherein: the time smoothing parameter is a function of the initial or updated values of multiple masks corresponding to different time points, and the frequency smoothing parameter represents a variable number of time-frequency bins along the frequency axis that are used in updating the initial value.