# US 2013/0156221 A1 · Signal processing apparatus and signal processing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156221 A1 - Document ID: US20130156221A1 - Status: Published application - Kind: A1 - Application number: 13/685,079 - Filed: 2012-11-26 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: Fujitsu Limited - Inventors: Naoshi MATSUO - Web page: https://patentgrep.com/patent/US20130156221A1 ## CPC - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - G10L 25/84: for discriminating voice from noise - H04B 15/00: Suppression or limitation of noise or interference (by means associated with receiver H04B1/10) - H04R 1/406: {microphones} - G10L 2021/02168: {the estimation exclusively taking place during speech pauses} - H04R 2201/403: Linear arrays of transducers - H04R 2410/07: Mechanical or electrical reduction of wind noise generated by wind passing a microphone - H04R 2430/20: Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence) - H04R 2499/11: Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's - 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) - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H04B: TRANSMISSION ## Abstract A signal processing apparatus includes an adder that acquires a plurality of input signals from a plurality of microphones and calculates an added value obtained by adding the input signals together, a subtracter that acquires a plurality of input signals from the plurality of microphones and calculates a subtracted value obtained by subtracting one input signal from the other input signal, and a determination unit that determines whether noise is included in the input signals based on the added value and the subtracted value. ## Claims ### Claim 1 A signal processing apparatus comprising: an adder that acquires a plurality of input signals from a plurality of microphones and calculates an added value obtained by adding the input signals together; a subtracter that acquires a plurality of input signals from the plurality of microphones and calculates a subtracted value obtained by subtracting one input signal from the other input signal; and a determination unit that determines whether noise is included in the input signals based on the added value and the subtracted value. ### Claim 2 (depends on 1) The signal processing apparatus according to claim 1, further comprising: a gain calculator that calculates a gain based on the added value and the subtracted value; and a noise suppression unit that suppresses noise of the input signals based on the gain calculated by the gain calculator. ### Claim 3 (depends on 1) The signal processing apparatus according to claim 1, wherein the determination unit determines that noise is included in the input signals when a difference between the added value and the subtracted value is smaller than a threshold value. ### Claim 4 (depends on 1) The signal processing apparatus according to claim 1, further comprising a ratio calculator that calculates a ratio of the subtracted value to the added value, wherein the determination unit determines that noise is included in the input signals when a value of the ratio calculated by the ratio calculator is greater than or equal to a threshold value. ### Claim 5 (depends on 1) The signal processing apparatus according to claim 1, further comprising: a delay detector that acquires input signals from the plurality of microphones, changes a delay amount of each of the input signals, and detects delay amounts by which a correlation coefficient of the input signals is a maximum; and a delay unit that delays each of the input signals based on the delay amounts detected by the delay detector, wherein the adder calculates the added value based on the input signals delayed by the delay unit, and the subtracter calculates the subtracted value based on the input signals delayed by the delay unit. ### Claim 6 (depends on 1) The signal processing apparatus according to claim 1, further comprising a frequency converter that acquires input signals from the plurality of microphones and converts each of the input signals into a signal on a frequency axis, wherein the adder calculates the added value based on each signal on the frequency axis, and the subtracter calculates the subtracted value based on each signal on the frequency axis. ### Claim 7 (depends on 2) The signal processing apparatus according to claim 2, further comprising a ratio calculator that calculates a ratio of the subtracted value to the added value, wherein the gain calculator calculates the gain based on a value of the ratio and information indicating a relationship between the gain and the value of the ratio which varies according to a distance between the microphones. ### Claim 8 (depends on 4) The signal processing apparatus according to claim 4, wherein the ratio calculator calculates a ratio of a value obtained by squaring the subtracted value to a value obtained by squaring the added value. ### Claim 9 (depends on 4) The signal processing apparatus according to claim 4, wherein the ratio calculator calculates a ratio of an absolute value of the subtracted value to an absolute value of the added value. ### Claim 10 (depends on 2) The signal processing apparatus according to claim 2, wherein the adder calculates a first added value obtained by adding together input signals acquired from a first microphone and a second microphone and a second added value obtained by adding together input signals acquired from a third microphone and a fourth microphone, the subtracter calculates a first subtracted value obtained by subtracting an input signal acquired from the second microphone from an input signal acquired from the first microphone and a second subtracted value obtained by subtracting an input signal acquired from the fourth microphone from an input signal acquired from the third microphone, and the gain calculator calculates a gain based on the first added value, the second added value, the first subtracted value, and the second subtracted value. ### Claim 11 A signal processing method comprising: acquiring a plurality of input signals from a plurality of microphones and calculating an added value obtained by adding the input signals together; acquiring a plurality of input signals from the plurality of microphones and calculating a subtracted value obtained by subtracting one input signal from the other input signal; and determining whether noise is included in the input signals based on the added value and the subtracted value. ### Claim 12 A computer-readable recording medium having stored therein a program for causing a computer to execute a signal processing procedure comprising: acquiring a plurality of input signals from a plurality of microphones and calculating an added value obtained by adding the input signals together; acquiring a plurality of input signals from the plurality of microphones and calculating a subtracted value obtained by subtracting one input signal from the other input signal; and determining whether noise is included in the input signals based on the added value and the subtracted value.