# US 9,437,180 B2 · Adaptive noise reduction using level cues > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,180 B2 - Document ID: US9437180B2 - Status: Granted - Kind: B2 - Application number: 14/222,255 - Filed: 2014-03-21 - Published: 2014-07-24 - Granted: 2016-09-06 - Earliest claimed: 2010-01-26 - Assignees: Knowles Electronics, LLC - Applicants: Knowles Electronics, LLC - Inventors: Carlo Murgia; Carlos Avendano; Karim Younes; Mark Every; Ye Jiang - Web page: https://patentgrep.com/patent/US9437180B2 ## CPC - G10K 11/16: Methods or devices for protecting against, or for damping, noise or other acoustic waves in general (G10K11/36 takes precedence) - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - 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 A system utilizing two pairs of microphones for noise suppression. Primary and secondary microphones may be positioned closely spaced to each other to provide acoustic signals used to achieve noise cancellation/suppression. An additional, tertiary microphone may be spaced with respect to either the primary microphone or the secondary microphone in a spread-microphone configuration for deriving level cues from audio signals provided by the tertiary and the primary or secondary microphone. The level cues are expressed via a level difference used to determine one or more cluster tracking control signal(s). The level difference-based cluster tracking signals are used to control adaptation of noise suppression. A noise cancelled primary acoustic signal and level difference-based cluster tracking control signals are used during post filtering to adaptively generate a mask to be applied to a speech estimate signal. ## Claims ### Claim 1 A method for suppressing noise, the method comprising: receiving three acoustic signals; determining level difference information from two pairs of the acoustic signals, one of the pairs comprising a first and second acoustic signal of the three acoustic signals, another of the pairs comprising a third acoustic signal of the acoustic signals and one of the first and second acoustic signals, wherein a primary acoustic signal comprises one of the three acoustic signals; and performing noise cancellation on the primary acoustic signal by subtracting a noise component from the primary acoustic signal, the noise component based at least in part on the level difference information. ### Claim 2 (depends on 1) The method of claim 1, further comprising adapting the noise cancellation of the primary acoustic signal based at least in part on the level difference information. ### Claim 3 (depends on 1) The method of claim 1, further comprising performing noise cancellation by noise subtraction blocks configured in a cascade, the noise subtraction blocks processing any of the three acoustic signals. ### Claim 4 (depends on 3) The method of claim 3, further comprising: receiving, by a first noise subtraction block in the cascade, the one of the pairs of the three acoustic signals; and receiving, by a next noise subtraction block in the cascade, an output of the first noise subtraction block and one of the three acoustic signals not included in the one of the pairs of the three acoustic signals received by the first noise subtraction block. ### Claim 5 (depends on 4) The method of claim 4, wherein the output of the first noise subtraction block is a noise reference signal, further comprising: generating a noise estimate based at least in part on the noise reference signal and a speech reference output of any of the noise subtraction blocks; and providing the noise estimate to a post processor. ### Claim 6 (depends on 5) The method of claim 5, wherein the level difference information is normalized via a cluster tracker module. ### Claim 7 (depends on 1) The method of claim 1, wherein the three acoustic signals further include a secondary acoustic signal and a tertiary acoustic signal. ### Claim 8 (depends on 1) The method of claim 1, further comprising: generating the level difference information using energy level estimates; and providing the level difference information to a cluster tracker module, the cluster tracker module being configured for controlling adaptation of noise suppression. ### Claim 9 A system for suppressing noise, the system comprising: a frequency analysis module stored in memory and executed by a processor to receive three acoustic signals; a level difference module stored in memory and executed by a processor to determine level difference information from two pairs of acoustic signals, one of the pairs of the acoustic signals comprising a first and second acoustic signal of the three acoustic signals, another of the pairs of acoustic signals comprising a third acoustic signal of the three acoustic signals and one of the first and second acoustic signals, wherein a primary acoustic signal comprises one of the three acoustic signals; and a noise cancellation module stored in memory and executed by a processor to perform noise cancellation on the primary acoustic signal by subtracting a noise component from the primary acoustic signal, the noise component based at least in part on the level difference information. ### Claim 10 (depends on 9) The system of claim 9, wherein a post filter module is executed to adapt the noise cancellation of the primary acoustic signal based at least in part on the level difference information. ### Claim 11 (depends on 9) The system of claim 9, further comprising noise subtraction blocks configured in a cascade, the noise subtraction blocks performing noise cancellation by processing any of the three acoustic signals. ### Claim 12 (depends on 11) The system of claim 11, wherein a first noise subtraction block in the cascade, when executed by a processor, receives the one of the pairs of the three acoustic signals, and a next noise subtraction block in the cascade, when executed by a processor, receives an output of the first noise subtraction block and one of the three acoustic signals not included in the one of the pairs of the acoustic signals received by the first noise subtraction block. ### Claim 13 (depends on 12) The system of claim 12, wherein the output of the first noise subtraction block is a noise reference signal, the system further comprising a noise estimate module, which, when executed, generates a noise estimate based at least in part on the noise reference signal and a speech reference output of any noise subtraction block, and provides the noise estimate to a post processor. ### Claim 14 (depends on 13) The system of claim 13, wherein the level difference information is normalized via a cluster tracker module for controlling adaptation of noise suppression. ### Claim 15 A non-transitory computer readable storage medium having embodied thereon a program, the program being executable by a processor to perform a method for suppressing noise, the method comprising: receiving three acoustic signals; determining level difference information from two pairs of the acoustic signals, one of the pairs comprising a first and second acoustic signal of the three acoustic signals, another of the pairs comprising a third acoustic signal of the acoustic signals and one of the first and second acoustic signals, wherein a primary acoustic signal comprises one of the three acoustic signals; and performing noise cancellation on the primary acoustic signal by subtracting a noise component from the primary acoustic signal, the noise component based at least in part on the level difference information. ### Claim 16 (depends on 15) The non-transitory computer readable storage medium of claim 15, the method further comprising adapting the noise cancellation of the primary acoustic signal based at least in part on the level difference information. ### Claim 17 (depends on 15) The non-transitory computer readable storage medium of claim 15, the method further comprising performing noise cancellation by noise subtraction blocks configured in a cascade, the noise subtraction blocks processing any of the three acoustic signals. ### Claim 18 (depends on 17) The non-transitory computer readable storage medium of claim 17, the method further comprising: receiving, by a first noise subtraction block in the cascade, the one of the pairs of the three acoustic signals; and receiving, by a next noise subtraction block in the cascade, an output of the first noise subtraction block and one of the three acoustic signals not included in the one of the pairs of the three acoustic signals received by the first noise subtraction block. ### Claim 19 (depends on 18) The non-transitory computer readable storage medium of claim 18, wherein the output of the first noise subtraction block is a noise reference signal, the method further comprising: generating a noise estimate based at least in part on the noise reference signal and a speech reference output of any of the noise subtraction blocks; and providing the noise estimate to a post processor, wherein the level difference information is normalized. ### Claim 20 (depends on 19) The non-transitory computer readable storage medium of claim 19, further comprising: generating the level difference information using energy level estimates determined via at least one frequency analysis module; and providing the level difference information to a cluster tracker module, the cluster tracker module being configured to control adaptation of noise suppression.