# US 8,787,591 B2 · Method and system for interference suppression using blind source separation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,591 B2 - Document ID: US8787591B2 - Status: Granted - Kind: B2 - Application number: 12/880,059 - Filed: 2010-09-10 - Published: 2011-03-17 - Granted: 2014-07-22 - Earliest claimed: 2009-09-11 - Assignees: Texas Instruments Incorporated - Applicants: Devangi Nikunj Parikh; Muhammad Zubair Ikram - Inventors: Devangi Nikunj Parikh; Muhammad Zubair Ikram - Web page: https://patentgrep.com/patent/US8787591B2 ## CPC - G10L 21/0208: Noise filtering - G10L 21/0272: Voice signal separating - H04M 1/60: including speech amplifiers - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) ## Abstract A method of interference suppression is provided that includes receiving a first audio signal from a first audio capture device and a second audio signal from a second audio capture device wherein the first audio signal includes a first combination of desired audio content and interference and the second audio signal includes a second combination of the desired audio content and the interference, performing blind source separation using the first audio signal and the second audio signal to generate an output interference signal and an output audio signal including the desired audio content with the interference suppressed, estimating interference remaining in the output audio signal using the output interference signal, and subtracting the estimated interference from the output audio signal to generate a final output audio signal with the interference further suppressed. ## Claims ### Claim 1 A method of interference suppression, the method comprising: receiving a first audio signal from a first audio capture device and a second audio signal from a second audio capture device wherein the first audio signal comprises a first combination of desired audio content and interference and the second audio signal comprises a second combination of the desired audio content and the interference; and performing blind source separation using the first audio signal and the second audio signal to generate an output audio signal comprising the desired audio content with the interference suppressed, wherein the blind source separation uses a hyperbolic tangent function to separate the desired audio content and the interference, wherein the tangent hyperbolic function is approximated using a lookup table and interpolation between values in the lookup table. ### Claim 2 (depends on 1) The method of claim 1, wherein the desired audio content is speech. ### Claim 3 (depends on 1) The method of claim 1, further comprising: estimating interference remaining in the output audio signal using an output interference signal generated by the blind source separation; and subtracting the estimated interference from the output audio signal to generate a final output audio signal with the interference further suppressed. ### Claim 4 (depends on 3) The method of claim 3, wherein estimating interference comprises applying a transform vector to the output interference signal that maps a magnitude spectrum of the interference in the output interference signal to a magnitude spectrum of the interference in the output audio signal. ### Claim 5 (depends on 3) The method of claim 3, wherein estimating interference comprises: detecting a silence interval of a predetermined length in the output audio signal; computing a transform vector as a product of a matrix comprising a magnitude spectrum of the silent interval and a pseudo inverse of a matrix comprising a magnitude spectrum of a corresponding interval in the output interference signal; and applying the transform vector to a block of the output interference signal. ### Claim 6 (depends on 3) The method of claim 3, wherein subtracting the estimated interference comprises: estimating a magnitude spectrum of a block of the final output audio signal based on the estimated interference; estimating a frequency spectrum of the block of the final output audio signal using the estimated magnitude spectrum and a phase of a frequency spectrum of a corresponding block of the output audio signal; and computing an inverse Fourier transform of the estimated frequency spectrum to generate the block of the final output audio signal. ### Claim 7 (depends on 1) The method of claim 1, wherein the first audio capture device and the second audio capture device are comprised in a cellular telephone. ### Claim 8 (depends on 7) The method of claim 7, wherein the first audio capture device is located on a lower front portion of the cellular telephone and the second audio capture device is located on an upper back portion of the cellular telephone. ### Claim 9 A method of interference suppression, the method comprising: receiving a first audio signal from a first audio capture device and a second audio signal from a second audio capture device wherein the first audio signal comprises a first combination of desired audio content and interference and the second audio signal comprises a second combination of the desired audio content and the interference; performing blind source separation using the first audio signal and the second audio signal to generate an output interference signal and an output audio signal comprising the desired audio content with the interference suppressed, wherein the blind source separation uses a hyperbolic tangent function to separate the desired audio content and the interference, and wherein the tangent hyperbolic function is approximated using a lookup table and interpolation between values in the lookup table; estimating interference remaining in the output audio signal using the output interference signal; and subtracting the estimated interference from the output audio signal to generate a final output audio signal with the interference further suppressed. ### Claim 10 (depends on 9) The method of claim 9, wherein the desired audio content is speech. ### Claim 11 (depends on 9) The method of claim 9, wherein estimating interference comprises applying a transform vector to the output interference signal that maps a magnitude spectrum of the interference in the output interference signal to a magnitude spectrum of the interference in the output audio signal. ### Claim 12 (depends on 9) The method of claim 9, wherein estimating interference comprises: detecting a silence interval of a predetermined length in the output audio signal; computing a transform vector as a product of a matrix comprising a magnitude spectrum of the silent interval and a pseudo inverse of a matrix comprising a magnitude spectrum of a corresponding interval in the output interference signal; and applying the transform vector to a block of the output interference signal. ### Claim 13 (depends on 9) The method of claim 9, wherein subtracting the estimated interference comprises: estimating a magnitude spectrum of a block of the final output audio signal based on the estimated interference; estimating a frequency spectrum of the block of the final output audio signal using the estimated magnitude spectrum and a phase of a frequency spectrum of a corresponding block of the output audio signal; and computing an inverse Fourier transform of the estimated frequency spectrum to generate the block of the final output audio signal. ### Claim 14 (depends on 9) The method of claim 9, wherein the first audio capture device and the second audio capture device are comprised in a cellular telephone. ### Claim 15 (depends on 14) The method of claim 14, wherein the first audio capture device is located on a lower front portion of the cellular telephone and the second audio capture device is located on an upper back portion of the cellular telephone.