US9271075B2 - Signal processing apparatus and signal processing method - Google Patents

Signal processing apparatus and signal processing method Download PDF

Info

Publication number
US9271075B2
US9271075B2 US13/685,079 US201213685079A US9271075B2 US 9271075 B2 US9271075 B2 US 9271075B2 US 201213685079 A US201213685079 A US 201213685079A US 9271075 B2 US9271075 B2 US 9271075B2
Authority
US
United States
Prior art keywords
value
input signals
gain
calculates
ratio
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related, expires
Application number
US13/685,079
Other versions
US20130156221A1 (en
Inventor
Naoshi Matsuo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujitsu Ltd
WhiteCryption Corp
Original Assignee
Fujitsu Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
Assigned to FUJITSU LIMITED reassignment FUJITSU LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MATSUO, NAOSHI
Publication of US20130156221A1 publication Critical patent/US20130156221A1/en
Application granted granted Critical
Publication of US9271075B2 publication Critical patent/US9271075B2/en
Assigned to SIA SYNCROSOFT reassignment SIA SYNCROSOFT ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HARDER, WULF, PEETERS, BERND, RESAS, UWE, WEBER, STEFAN
Assigned to WHITECRYPTION CORPORATION reassignment WHITECRYPTION CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SIA WHITECRYPTION
Assigned to SIA WHITECRYPTION reassignment SIA WHITECRYPTION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SIA SYNCROSOFT
Expired - Fee Related legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
    • G10L25/78—Detection of presence or absence of voice signals
    • G10L25/84—Detection of presence or absence of voice signals for discriminating voice from noise
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
    • H04R1/406—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L21/00—Processing of the speech or voice signal to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
    • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
    • G10L21/0208—Noise filtering
    • G10L21/0216—Noise filtering characterised by the method used for estimating noise
    • G10L2021/02168—Noise filtering characterised by the method used for estimating noise the estimation exclusively taking place during speech pauses
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/40—Details of arrangements for obtaining desired directional characteristic by combining a number of identical transducers covered by H04R1/40 but not provided for in any of its subgroups
    • H04R2201/403—Linear arrays of transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2410/00—Microphones
    • H04R2410/07—Mechanical or electrical reduction of wind noise generated by wind passing a microphone
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2430/00—Signal processing covered by H04R, not provided for in its groups
    • H04R2430/20—Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/11—Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's

Definitions

  • FIG. 10 is a diagram illustrating an example of the conventional apparatus. As illustrated in FIG. 10 , a conventional apparatus 10 is connected to microphones 10 a and 10 b . The microphones 10 a and 10 b are spaced apart from each other by a predetermined distance.
  • the conventional apparatus 10 includes a correlation analyzer 11 , a noise analyzer 12 , and a noise reduction unit 13 .
  • the microphone 10 a is a microphone which converts collected sound into an input signal Lin(t) and outputs the input signal Lin(t) to the conventional apparatus 10 .
  • the microphone 10 b is a microphone which converts collected sound into an input signal Rin(t) and outputs the input signal Rin(t) to the conventional apparatus 10 .
  • t corresponds to a sampling number of the input signal.
  • the correlation analyzer 11 calculates a correlation value r(t) between the input signal Lin(t) and the input signal Rin(t) by using the formula (1).
  • the correlation analyzer 11 sequentially changes the value of i from 1 to n and calculates a correlation value r(t). For example, the value of n is 128.
  • the correlation analyzer 11 outputs the correlation value r(t) to the noise analyzer 12 .
  • r ( t ) ⁇ L in( t ⁇ i ) R in( t ⁇ i )/(( ⁇ L in( t ⁇ i ) 2 ) 1/2 ( ⁇ R in( t ⁇ i ) 2 ) 1/2 ) (1)
  • the noise analyzer 12 determines that there is noise of wind and outputs control information to turn down volume to the noise reduction unit 13 .
  • the noise reduction unit 13 adjusts the volumes of the input signals Lin(t) and Rin(t) and outputs the input signals Lin(t) and Rin(t) to an external apparatus. For example, when the noise reduction unit 13 receives the control information to turn down volume, the noise reduction unit 13 turns down the volumes of the input signals Lin(t) and Rin(t) and outputs the input signals Lin(t) and Rin(t) to the external apparatus.
  • Patent Document 1 Japanese Laid-open Patent Publication No. 2004-289762
  • Patent Document 2 Japanese Laid-open Patent Publication No. 2009-005133
  • 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.
  • FIG. 1 is a diagram illustrating a configuration of a signal processing apparatus according to a first embodiment
  • FIG. 2 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the first embodiment
  • FIG. 3 is a diagram for explaining an effect of the present invention compared with a conventional apparatus
  • FIG. 4 is a diagram illustrating a configuration of a signal processing apparatus according to a second embodiment
  • FIG. 5 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the second embodiment
  • FIG. 6 is a diagram illustrating a configuration of a signal processing apparatus according to a third embodiment
  • FIG. 7 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the third embodiment.
  • FIG. 8 is a diagram for explaining another process of a gain calculator
  • FIG. 9 is a diagram illustrating an example of a computer that executes a signal processing program.
  • FIG. 10 is a diagram illustrating an example of a conventional apparatus.
  • FIG. 1 is a diagram illustrating a configuration of a signal processing apparatus according to a first embodiment. As illustrated in FIG. 1 , a signal processing apparatus 100 is connected to microphones 10 a and 10 b . The microphones 10 a and 10 b are spaced apart from each other by a predetermined distance.
  • the signal processing apparatus 100 includes an adder 110 , a subtracter 120 , and power calculators 130 a and 130 b .
  • the signal processing apparatus 100 also includes a ratio calculator 140 , a determination unit 150 , a gain calculator 160 , and a noise suppression unit 170 .
  • the microphone 10 a is a microphone which converts collected sound into an input signal Lin(t) and outputs the input signal Lin(t) to the signal processing apparatus 100 .
  • the microphone 10 b is a microphone which converts collected sound into an input signal Rin(t) and outputs the input signal Rin(t) to the signal processing apparatus 100 .
  • t corresponds to a sampling number of the input signal.
  • the adder 110 calculates an added value p(t) by adding the input signal Lin(t) and the input signal Rin(t) together.
  • the added value p(t) is represented by the formula (2).
  • the adder 110 outputs the added value p(t) to the power calculator 130 a.
  • p ( t ) L in( t )+ R in( t ) (2)
  • the subtracter 120 calculates an subtracted value m(t) by subtracting the input signal Rin(t) from the input signal Lin(t).
  • the subtracted value m(t) is represented by the formula (3).
  • the subtracter 120 outputs the subtracted value m(t) to the power calculator 130 b.
  • m ( t ) L in( t ) ⁇ R in( t ) (3)
  • the power calculator 130 a calculates a power Ppow(t) by summing up squared values of the added value p(t) of different sampling numbers.
  • the power Ppow(t) is represented by the formula (4).
  • the power calculator 130 a sequentially changes the value of j from 1 to n and calculates the power Ppow(t).
  • the value of n is a natural number. For example, the value of n is 128.
  • the power calculator 130 a outputs the power Ppow(t) to the ratio calculator 140 .
  • P pow( t ) ⁇ p ( t ⁇ j ) 2 (4)
  • the power calculator 130 b calculates a power Mpow(t) by summing up squared values of the subtracted value m(t) of different sampling numbers.
  • the power Mpow(t) is represented by the formula (5).
  • the power calculator 130 b sequentially changes the value of j from 1 to n and calculates the power Mpow(t).
  • the value of n is a natural number. For example, the value of n is 128.
  • the power calculator 130 b outputs the power Mpow(t) to the ratio calculator 140 .
  • M pow( t ) ⁇ m ( t ⁇ j ) 2 (5)
  • the ratio calculator 140 calculates a ratio v(t) of the power Ppow(t) and the power Mpow(t). For example, the ratio calculator 140 calculates the ratio v(t) by the formula (6). The ratio calculator 140 outputs the ratio v(t) to the determination unit 150 and the gain calculator 160 .
  • v(t) may be a square root of the ratio of the power Ppow(t) and the power Mpow(t).
  • v ( t ) M pow( t )/ P pow( t ) (6)
  • the determination unit 150 determines whether noise is included in the input signals Lin(t) and Rin(t) based on the ratio v(t). When the value of the ratio v(t) is greater than or equal to a predetermined threshold value, the determination unit 150 determines that noise is included in the input signals Lin(t) and Rin(t). The determination unit 150 outputs a determination result to the gain calculator 160 .
  • the gain calculator 160 calculates a gain based on the ratio v(t).
  • the gain calculator 160 first calculates g′(t) by the formula (7) and thereafter calculates a gain g(t) by the formula (8).
  • g ′( t ) 1 ⁇ v ( t ) (7)
  • g ( t ) max( g ′( t ), ⁇ ) (8)
  • ⁇ is a lower limit value greater than or equal to 0 and smaller than or equal to 1.
  • the gain calculator 160 calculates g′(t) and thereafter calculates the larger value of g′(t) and ⁇ as the gain g(t).
  • the gain calculator 160 outputs the gain g(t) to the noise suppression unit 170 .
  • the gain calculator 160 may calculate the gain g(t) when noise is included in the input signals Lin(t) and Rin(t) based on the determination result of the determination unit 150 . On the other hand, when noise is not included in the input signals Lin(t) and Rin(t), the gain calculator 160 may set 1 to the gain g(t) and output the gain g(t) to the noise suppression unit 170 .
  • the noise suppression unit 170 suppresses noise by multiplying the input signals Lin(t) and Rin(t) by the gain g(t). For example, the noise suppression unit 170 generates output signals Lout(t) and Rout(t) from the input signals Lin(t) and Rin(t) and outputs the generated signals to an external apparatus.
  • FIG. 2 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the first embodiment.
  • the process illustrated in FIG. 2 is performed when input signals are received from the microphones 10 a and 10 b.
  • the signal processing apparatus 100 calculates the added value p(t) obtained by adding together the input signals Lin(t) and Rin(t) of the microphones 10 a and 10 b (step S 101 ).
  • the signal processing apparatus 100 calculates the subtracted value m(t) obtained by subtracting the input signal Rin(t) of one microphone 10 b from the input signal Lin(t) of the other microphone 10 a (step S 102 ).
  • the signal processing apparatus 100 calculates the power Ppow(t) based on the added value p(t) (step S 103 ).
  • the signal processing apparatus 100 calculates the power Mpow(t) based on the subtracted value m(t) (step S 104 ).
  • the signal processing apparatus 100 calculates the ratio v(t) (step S 105 ) and determines whether noise is included (step S 106 ).
  • the signal processing apparatus 100 calculates the gain g(t) based on the ratio v(t) (step S 107 ).
  • the signal processing apparatus 100 outputs the output signals Lout(t) and Rout(t) whose noise is suppressed based on the gain g(t) (step S 108 ).
  • the determination unit 150 determines whether noise is included in the input signals Lin(t) and Rin(t) based on the added value p(t) calculated by the adder 110 and the subtracted value m(t) calculated by the subtracter 120 . Therefore, it is possible to accurately determine whether noise is included, so that noise included in the input signals can be sufficiently suppressed by using the determination result.
  • the lower the frequency the stronger the correlation between the input signals. This is because the lower the frequency, the smaller the variation of waveforms in the time axis direction, so that the waveforms have similar shapes.
  • An extreme example is a direct current. Therefore, in order to strengthen the correlation, the adder 110 sums up the input signals. On the other hand, in order to suppress the correlation, the subtracter 120 subtracts one input signal from the other input signal.
  • noise can be accurately detected by using the ratio of the “power of (Lin(t) ⁇ Rin(t))” based on the “power of (Lin(t)+Rin(t))”. Also, an appropriate gain can be calculated by using the ratio of the “power of (Lin(t)-Rin(t))” based on the “power of (Lin(t)+Rin(t))”, and a noise component included in the input signals can be suppressed by using the gain.
  • FIG. 3 is a diagram for explaining an effect of the present invention compared with a conventional apparatus.
  • Signals 20 A in FIG. 3 indicates a relationship between the sampling number and the gain g(t) of the conventional apparatus.
  • Signals 20 B in FIG. 3 indicates a relationship between the sampling number and the gain g(t) of the signal processing apparatus 100 .
  • Sections 21 in the signals 20 A and 20 B are sections including voice.
  • the gain g(t) in sections including only wind hitting noise is reduced while the gain g(t) in the sections 21 is substantially maintained at 1. Therefore, in the present invention, it is possible to turn down volume of a part of input signals including noise without turning down volume of whole input signals in voice sections.
  • the determination unit 150 determines whether noise is included based on the value of the ratio v(t). However, it is not limited to this.
  • the determination unit 150 may obtain a difference between the Ppow(t) and the Mpow(t), and when the difference value is smaller than a predetermined threshold value, the determination unit 150 may determine that noise is included in the input signals.
  • the signal processing apparatus 100 may be configured by integrating the determination unit 150 and the gain calculator 160 together.
  • FIG. 4 is a diagram illustrating a configuration of the signal processing apparatus according to the second embodiment.
  • a signal processing apparatus 200 is connected to the microphones 10 a and 10 b .
  • the microphones 10 a and 10 b are spaced apart from each other by a predetermined distance.
  • the description about the microphones 10 a and 10 b is the same as that in the first embodiment.
  • the signal processing apparatus 200 includes a delay detector 201 and delay devices 202 a and 202 b .
  • the signal processing apparatus 200 also includes an adder 210 , a subtracter 220 , and power calculators 230 a and 230 b .
  • the signal processing apparatus 200 also includes a ratio calculator 240 , a determination unit 250 , a gain calculator 260 , and a noise suppression unit 270 .
  • the delay detector 201 calculates a correlation coefficient c(d) between the input signal Lin(t) and the input signal Rin(t) by the formula (13).
  • the delay detector 201 changes a delay amount d and detects a delay amount dmax by which the value of correlation coefficient c(d) is the maximum.
  • c ( d ) ⁇ L in( t ) R in( t ⁇ d )/(( ⁇ L in( t ) 2 ) 1/2 ( ⁇ R in( t ⁇ d ) 2 ) 1/2 ) (13)
  • the delay detector 201 calculates a delay amount dL applied to the input signal from the microphone 10 a and a delay amount dR applied to the input signal from the microphone 10 b in order to synchronize the input signals inputted from the microphones 10 a and 10 b .
  • a calculation example of the delay amounts dL and dR will be described below.
  • the delay detector 201 sets the value of dL to 0 and sets the value of dR to the value of the dmax. Then, the delay detector 201 outputs the dL to the delay device 202 a and outputs the dR to the delay device 202 b.
  • the delay detector 201 sets the value of dL to the absolute value of the dmax and sets the value of dR to 0. Then, the delay detector 201 outputs the dL to the delay device 202 a and outputs the dR to the delay device 202 b.
  • the delay device 202 a performs a delay process of the input signal Lin(t) from the microphone 10 a .
  • the delay device 202 a outputs an input signal Lin(t ⁇ dL) obtained by performing a delay process on the input signal Lin(t) to the adder 210 and the subtracter 220 .
  • the adder 210 calculates an added value p(t) by adding together the input signals Lin(t ⁇ dL) and Rin(t ⁇ dR) whose delay amounts are adjusted.
  • the adder 210 outputs the added value p(t) to the power calculator 230 a.
  • the descriptions about the power calculators 230 a and 230 b , the ratio calculator 240 , the determination unit 250 , the gain calculator 260 , and the noise suppression unit 270 are the same as those of the power calculators 130 a and 130 b , the ratio calculator 140 , the determination unit 150 , the gain calculator 160 , and the noise suppression unit 170 illustrated in FIG. 1 .
  • the signal processing apparatus 200 detects the maximum value of the correlation coefficient c(d) between the input signal Lin(t) and the input signal Rin(t) and calculates the delay amounts dL and dR for synchronization (step S 201 ).
  • the signal processing apparatus 200 calculates the p(t) by performing synchronous addition (step S 202 ) and calculates the m(t) by performing synchronous subtraction (step S 203 ).
  • the signal processing apparatus 200 calculates the power Ppow(t) based on the added value p(t) (step S 204 ).
  • the signal processing apparatus 200 calculates the power Mpow(t) based on the subtracted value m(t) (step S 205 ).
  • the signal processing apparatus 200 calculates the ratio v(t) (step S 206 ) and determines whether noise is included (step S 207 ).
  • the signal processing apparatus 200 calculates the gain g(t) based on the ratio v(t) (step S 208 ).
  • the signal processing apparatus 200 outputs the output signals Lout(t) and Rout(t) whose noise is suppressed based on the gain g(t) (step S 209 ).
  • the delay detector 201 calculates the delay amounts dL and dR and the delay devices 202 a and 202 b synchronize the input signals.
  • the determination unit 250 determines whether noise is included in the input signals Lin(t) and Rin(t) based on the added value p(t) calculated by the adder 210 and the subtracted value m(t) calculated by the subtracter 220 . Therefore, even if the timings when voice of a user is collected by the microphones 10 a and 10 b are different from each other, the input signals can be synchronized by adjusting the delay amounts. Thus, it is possible to accurately determine whether noise is included in a direction of a user whose voice is desired to be recorded, so that noise included in the input signals can be suppressed by using the determination result.
  • FIG. 6 is a diagram illustrating a configuration of the signal processing apparatus according to the third embodiment.
  • a signal processing apparatus 300 is connected to the microphones 10 a and 10 b .
  • the microphones 10 a and 10 b are spaced apart from each other by a predetermined distance.
  • the description about the microphones 10 a and 10 b is the same as that in the first embodiment.
  • the FFT 301 a positions a Hanning window with 50% overlap on the input signal Lin(t) acquired from the microphone 10 a and converts the input signal Lin(t) into a signal on the frequency axis by fast Fourier transform.
  • the input signal Lin(t) converted into a signal on the frequency axis is represented as LIN(i, f).
  • i is a number of an analysis frame on which FFT is performed and f indicates the frequency.
  • the FFT 301 a outputs the LIN(i, f) to the adder 310 , the subtracter 320 , and the noise suppression unit 370 .
  • the FFT 301 b positions a Hanning window with 50% overlap on the input signal Rin(t) acquired from the microphone 10 b and converts the input signal Rin(t) into a signal on the frequency axis by fast Fourier transform.
  • the input signal Rin(t) converted into a signal on the frequency axis is represented as RIN(i, f).
  • the FFT 301 b outputs the RIN(i, f) to the adder 310 , the subtracter 320 , and the noise suppression unit 370 .
  • the FFTs 301 a and 301 b are an example of a frequency converter.
  • the adder 310 is a processing unit which calculates an added value p(i, f) by adding the input signal LIN(i, f) and the input signal RIN(i, f) together.
  • the added value p(i, f) is represented by the formula (14).
  • the adder 310 outputs the added value p(i, f) to the power calculator 330 a.
  • p ( i, f ) L IN( i, f )+ R IN( i, f ) (14)
  • the subtracter 320 calculates a subtracted value m(i, f) by subtracting the input signal RIN(i, f) from the input signal LIN(i, f).
  • the subtracted value m(i, f) is represented by the formula (15).
  • the subtracter 320 outputs the subtracted value m(i, f) to the power calculator 330 b.
  • m ( i, f ) L IN( i, f ) ⁇ R IN( i, f ) (15)
  • the power calculator 330 a calculates a power Ppow(i, f) by summing up squared values of the added value p(i, f) of different frame numbers.
  • the power Ppow(i, f) is represented by the formula (16).
  • the power calculator 330 a sequentially changes the value of j from 1 to n and calculates the power Ppow(i, f).
  • the value of n is a natural number. For example, the value of n is 128.
  • the power calculator 330 a outputs the power Ppow(i, f) to the ratio calculator 340 .
  • P pow( i, f ) ⁇ p ( i ⁇ j, f ) (16)
  • the power calculator 330 b calculates a power Mpow(i, f) by summing up squared values of the subtracted value m(i, f) of different frame numbers.
  • the power Mpow(i, f) is represented by the formula (17).
  • the power calculator 330 b sequentially changes the value of j from 1 to n and calculates the power Mpow(i, f).
  • the value of n is a natural number. For example, the value of n is 128.
  • the power calculator 330 b outputs the power Mpow(i, f) to the ratio calculator 340 .
  • M pow( i, f ) ⁇ m ( i ⁇ j, f ) (17)
  • the ratio calculator 340 calculates a ratio v(i, f) of the power Ppow(i, f) and the power Mpow(i, f). For example, the ratio calculator 340 calculates the ratio v(i, f) by the formula (18). The ratio calculator 340 outputs the ratio v(i, f) to the determination unit 350 and the gain calculator 360 .
  • v ( i, f ) M pow( i, f )/ P pow( i, f ) (18)
  • the determination unit 350 determines whether noise is included in the input signals LIN(i, f) and RIN(i, f) based on the ratio v(i, f). When the value of the ratio v(i, f) is greater than or equal to a predetermined threshold value, the determination unit 350 determines that noise is included in the input signals LIN(i, f) and RIN(i, f). The determination unit 350 outputs a determination result to the gain calculator 360 .
  • the gain calculator 360 calculates a gain based on the ratio v(i, f).
  • the gain calculator 360 first calculates g′(i, f) by the formula (19) and thereafter calculates a gain g(i, f) by the formula (20).
  • g ′( i, f ) 1 ⁇ v ( i, f ) (19)
  • g ( i, f ) max( g ′( i, f ), ⁇ ) (20)
  • ⁇ is a lower limit value greater than or equal to 0 and smaller than or equal to 1.
  • the gain calculator 360 calculates g′(i, f) and thereafter calculates the larger value of g′(i, f) and ⁇ as the gain g(i, f).
  • the gain calculator 360 outputs the gain g(i, f) to the noise suppression unit 370 .
  • the gain calculator 360 may calculate the gain g(i, f) when noise is included in the input signals LIN(i, f) and RIN(i, f) based on the determination result of the determination unit 350 . On the other hand, when noise is not included in the input signals LIN(i, f) and RIN(i, f), the gain calculator 360 may set 1 to the gain g(i, f) and output the gain g(i, f) to the noise suppression unit 370 .
  • the noise suppression unit 370 suppresses noise by multiplying the input signals LIN(i, f) and RIN(i, f) by the gain g(i, f). For example, the noise suppression unit 370 generates output signals LOUT(i, f) and ROUT (i, f) from the input signals LIN(i, f) and RIN(i, f) and outputs the generated signals to the IFFTs 371 a and 371 b .
  • the output signals LOUT(i, f) and ROUT (i, f) are represented by the formulas (21) and (22).
  • the IFFT 371 a is a processing unit which generates a signal Lin(t) on the time axis by performing an inverse Fourier transform and 50% overlap addition on the LOUT(i, f).
  • the IFFT 371 a outputs the output signal Lin(t) to an external apparatus.
  • the IFFT 371 b is a processing unit which generates a signal Rin(t) on the time axis by performing an inverse Fourier transform and 50% overlap addition on the ROUT(i, f).
  • the IFFT 371 b outputs the output signal Rin(t) to an external apparatus.
  • FIG. 7 is a flowchart illustrating the processing procedure of the signal processing apparatus according to the third embodiment. For example, the process illustrated in FIG. 7 is performed when input signals are received from the microphones 10 a and 10 b.
  • the signal processing apparatus 300 calculates the LIN(i, f) and the RIN(i, f) by performing a Fourier transform on the input signals Lin(t) and Rin(t) of the microphones (step S 301 ).
  • the signal processing apparatus 300 calculates the added value p(i, f) obtained by adding together the input signals LIN(i, f) and RIN(i, f) of the microphones (step S 302 ).
  • the signal processing apparatus 300 calculates the subtracted value m(i, f) obtained by subtracting the input signal RIN(i, f) of one microphone from the input signal LIN(i, f) of the other microphone (step S 303 ).
  • the signal processing apparatus 300 calculates the power Ppow(i, f) based on the added value p(i, f) (step S 304 ).
  • the signal processing apparatus 300 calculates the power Mpow(i, f) based on the subtracted value m(i, f) (step S 305 ).
  • the signal processing apparatus 300 calculates the ratio v(i, f) (step S 306 ) and determines whether noise is included (step S 307 ).
  • the signal processing apparatus 300 calculates the gain g(i, f) based on the ratio v(i, f) (step S 308 ).
  • the signal processing apparatus 300 outputs the output signals LOUT(i, f) and ROUT(i, f) whose noise is suppressed based on the gain g(i, f) (step S 309 ).
  • the signal processing apparatus 300 performs an inverse Fourier transform on the output signals LOUT(i, f) and ROUT(i, f) and outputs Lout(t) and Rout(t) (step S 310 ).
  • the signal processing apparatus 300 performs a Fourier transform on the input signals Lin(t) and Rin(t) and determines whether there is noise at each frequency. Then, the signal processing apparatus 300 calculates the gain g(i, f) at each frequency and multiplies the input signals LIN(i, f) and RIN(i, f) at each frequency by the gain g(i, f). Therefore, noise at each frequency can be suppressed.
  • the processes of the aforementioned signal processing apparatuses 100 to 300 are an example.
  • another process of the signal processing apparatuses of the present invention will be described as a fourth embodiment.
  • the process according to the fourth embodiment will be described with reference to the configuration diagram in FIG. 1 .
  • the gain calculator 160 calculates the gain g(t) by using the formula (7) and the formula (8), it is not limited to this.
  • the gain calculator 160 may calculate the gain g(t) by using a decision table indicating a relationship between the gain g(t) and the ratio v(t) for each distance between the microphones 10 a and 10 b.
  • FIG. 8 is a diagram for explaining the other process of the gain calculator.
  • the gain calculator 160 defines that when the distance between the microphones 10 a and 10 b is 4.2 cm, the relationship between the gain g(t) and the ratio v(t) is a relationship changing as illustrated by a straight line 30 A in FIG. 8 .
  • the relationship illustrated by the straight line 30 A corresponds to the relationship of the formula (7).
  • the gain calculator 160 defines that when the distance between the microphones 10 a and 10 b is smaller than 4.2 cm, the relationship changes as illustrated by a curved line 30 B in FIG. 8 .
  • the gain calculator 160 sets the change rate of the gain g(t) larger than that indicated by the straight line 30 A when the value of the ratio v(t) is about 1 to 0.8.
  • the gain calculator 160 performs the process as described above, so that it is possible to accurately suppress noise corresponding to the change of characteristics of the input signals caused by the difference of the distance between the microphones.
  • the gain calculator 160 may acquire information of the distance between the microphones 10 a and 10 b in any manner. A user may input the distance into the signal processing apparatus 100 by using an input device.
  • the signal processing apparatus 100 may suppress noise by using microphones 10 c and 10 d not illustrated in the drawings in addition to the pair of microphones 10 a and 10 b .
  • the signal processing apparatus 100 calculates the ratio v(t) from the microphones 10 a and 10 b by the same process as that in the first embodiment.
  • the v(t) calculated from the microphones 10 a and 10 b is defined as v 1 ( t ).
  • the ratio v(t) is calculated from the microphones 10 c and 10 d by the same process as that in the first embodiment.
  • the v(t) calculated from the microphones 10 c and 10 d is defined as v 2 ( t ).
  • the signal processing apparatus 100 may adjust the input signals Lin(t) and Rin(t) by the gain g(t).
  • the signal processing apparatus 100 may obtain g′(t) by the formula (25) or the formula (26).
  • the processes after calculating the g′(t) is the same as that in the first embodiment.
  • the g′(t) may be obtained by subtracting the average value of the v 1 ( 1 ) and v 2 ( 2 ) from 1.
  • g ′( t ) 1 ⁇ v 1( t ) (25)
  • g ′( t ) 1 ⁇ v 2( t ) (26)
  • the gain g(t) is calculated by using the microphones 10 a to 10 d , so that it is possible to accurately suppress noise of the input signals even when there are a plurality of users.
  • the processing units included in the signal processing apparatuses 100 to 300 described in the first to the fourth embodiments correspond to integrated devices such as, for example, ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array). Also, the processing units correspond to electronic circuits such as CPU and MPU (Micro Processing Unit).
  • FIG. 9 is a diagram illustrating an example of the computer that executes the signal processing program.
  • a computer 400 includes a CPU 401 that performs various calculation processes, an input device 402 that receives input of data from a user, and a display 403 .
  • the computer 400 also includes a reading device 404 that reads a program and the like from a storage medium and an interface device 405 that transmits and receives data to and from another computer through a network.
  • the computer 400 also includes microphones 406 a and 406 b .
  • the computer 400 also includes a RAM 407 that temporarily stores various information and a hard disk device 408 .
  • the devices 401 to 408 are connected to a bus 409 .
  • the hard disk device 408 includes, for example, an addition program 408 a , a subtraction program 408 b , a power calculation program 408 c , a ratio calculation program 408 d , a determination program 408 e , a gain calculation program 408 f , and a noise suppression program 408 g .
  • the CPU 401 reads the programs 408 a to 408 g and develops the programs in the RAM 407 .
  • the addition program 408 a functions as an addition process 407 a .
  • the subtraction program 408 b functions as a subtraction process 407 b .
  • the power calculation program 408 c functions as a power calculation process 407 c .
  • the ratio calculation program 408 d functions as a ratio calculation process 407 d .
  • the determination program 408 e functions as a determination process 407 e .
  • the gain calculation program 408 f functions as a gain calculation process 407 f .
  • the noise suppression program 408 g functions as a noise suppression process 407 g.
  • the addition process 407 a corresponds to the adder 110 .
  • the subtraction process 407 b corresponds to the subtracter 120 .
  • the power calculation process 407 c corresponds to the power calculators 130 a and 130 b .
  • the ratio calculation process 407 d corresponds to the ratio calculator 140 .
  • the determination process 407 e corresponds to the determination unit 150 .
  • the gain calculation process 407 f corresponds to the gain calculator 160 .
  • the noise suppression process 407 g corresponds to the noise suppression unit 170 .
  • the programs 408 a to 408 g need not necessarily be stored in the hard disk device 408 from the beginning.
  • the programs are stored in a “portable physical medium” such as a flexible disk (FD), a CD-ROM, a DVD disk, a magneto-optical disk, and an IC card which are inserted in the computer 400 .
  • the computer 400 may read the programs 408 a to 408 g from these media and execute the programs.
  • the programs of the signal processing apparatuses 200 and 300 described in the second to the fourth embodiments are executed by the computer 400 in the same manner as the programs of the signal processing apparatus 100 .

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.

Description

CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-274742, filed on Dec. 15, 2011, the entire contents of which are incorporated herein by reference.
FIELD
The embodiments discussed herein are directed to a signal processing apparatus and the like.
BACKGROUND
When wind hits a microphone, a diaphragm included in the microphone vibrates largely, so that noise is included in an input signal. Here, if noise is included in the input signal, when speech recognition is performed or a hands-free phone call is made, the accuracy of the speech recognition and the quality of the phone call degrade. Therefore, in conventional speech recognition and a hands-free phone call, a conventional apparatus which suppresses irregular noise generated when wind hits the microphone is used.
FIG. 10 is a diagram illustrating an example of the conventional apparatus. As illustrated in FIG. 10, a conventional apparatus 10 is connected to microphones 10 a and 10 b. The microphones 10 a and 10 b are spaced apart from each other by a predetermined distance. The conventional apparatus 10 includes a correlation analyzer 11, a noise analyzer 12, and a noise reduction unit 13.
The microphone 10 a is a microphone which converts collected sound into an input signal Lin(t) and outputs the input signal Lin(t) to the conventional apparatus 10. The microphone 10 b is a microphone which converts collected sound into an input signal Rin(t) and outputs the input signal Rin(t) to the conventional apparatus 10. Here, t corresponds to a sampling number of the input signal.
The correlation analyzer 11 calculates a correlation value r(t) between the input signal Lin(t) and the input signal Rin(t) by using the formula (1). In the formula (1), the correlation analyzer 11 sequentially changes the value of i from 1 to n and calculates a correlation value r(t). For example, the value of n is 128. The correlation analyzer 11 outputs the correlation value r(t) to the noise analyzer 12.
r(t)=ΣLin(t−i)Rin(t−i)/((ΣLin(t−i)2)1/2(ΣRin(t−i)2)1/2)  (1)
When the value of the correlation value r(t) is small, the noise analyzer 12 determines that there is noise of wind and outputs control information to turn down volume to the noise reduction unit 13.
The noise reduction unit 13 adjusts the volumes of the input signals Lin(t) and Rin(t) and outputs the input signals Lin(t) and Rin(t) to an external apparatus. For example, when the noise reduction unit 13 receives the control information to turn down volume, the noise reduction unit 13 turns down the volumes of the input signals Lin(t) and Rin(t) and outputs the input signals Lin(t) and Rin(t) to the external apparatus.
Patent Document 1: Japanese Laid-open Patent Publication No. 2004-289762
Patent Document 2: Japanese Laid-open Patent Publication No. 2009-005133
However, in the conventional technique described above, there is a problem that noise included in a target input signal such as voice is not sufficiently suppressed.
For example, in the conventional technique, when wind blowing against the microphone is strong, the noise of the input signal can be suppressed. However, when wind blowing against the microphone is weak, the difference of correlation coefficient between a section including voice and a section including wind hitting noise is small, so that the noise is not accurately suppressed.
SUMMARY
According to an aspect of an embodiment, 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.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram illustrating a configuration of a signal processing apparatus according to a first embodiment;
FIG. 2 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the first embodiment;
FIG. 3 is a diagram for explaining an effect of the present invention compared with a conventional apparatus;
FIG. 4 is a diagram illustrating a configuration of a signal processing apparatus according to a second embodiment;
FIG. 5 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the second embodiment;
FIG. 6 is a diagram illustrating a configuration of a signal processing apparatus according to a third embodiment;
FIG. 7 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the third embodiment;
FIG. 8 is a diagram for explaining another process of a gain calculator;
FIG. 9 is a diagram illustrating an example of a computer that executes a signal processing program; and
FIG. 10 is a diagram illustrating an example of a conventional apparatus.
 DESCRIPTION OF EMBODIMENTS
Preferred embodiments of the present invention will be explained with reference to accompanying drawings. The present invention is not limited by the embodiments.
[a] First Embodiment
FIG. 1 is a diagram illustrating a configuration of a signal processing apparatus according to a first embodiment. As illustrated in FIG. 1, a signal processing apparatus 100 is connected to microphones 10 a and 10 b. The microphones 10 a and 10 b are spaced apart from each other by a predetermined distance.
The signal processing apparatus 100 includes an adder 110, a subtracter 120, and power calculators 130 a and 130 b. The signal processing apparatus 100 also includes a ratio calculator 140, a determination unit 150, a gain calculator 160, and a noise suppression unit 170.
The microphone 10 a is a microphone which converts collected sound into an input signal Lin(t) and outputs the input signal Lin(t) to the signal processing apparatus 100. The microphone 10 b is a microphone which converts collected sound into an input signal Rin(t) and outputs the input signal Rin(t) to the signal processing apparatus 100. Here, t corresponds to a sampling number of the input signal.
The adder 110 calculates an added value p(t) by adding the input signal Lin(t) and the input signal Rin(t) together. The added value p(t) is represented by the formula (2). The adder 110 outputs the added value p(t) to the power calculator 130 a.
p(t)=Lin(t)+Rin(t)  (2)
The subtracter 120 calculates an subtracted value m(t) by subtracting the input signal Rin(t) from the input signal Lin(t). The subtracted value m(t) is represented by the formula (3). The subtracter 120 outputs the subtracted value m(t) to the power calculator 130 b.
m(t)=Lin(t)−Rin(t)  (3)
The power calculator 130 a calculates a power Ppow(t) by summing up squared values of the added value p(t) of different sampling numbers. The power Ppow(t) is represented by the formula (4). The power calculator 130 a sequentially changes the value of j from 1 to n and calculates the power Ppow(t). The value of n is a natural number. For example, the value of n is 128. The power calculator 130 a outputs the power Ppow(t) to the ratio calculator 140.
Ppow(t)=Σp(t−j)2  (4)
The power calculator 130 b calculates a power Mpow(t) by summing up squared values of the subtracted value m(t) of different sampling numbers. The power Mpow(t) is represented by the formula (5). The power calculator 130 b sequentially changes the value of j from 1 to n and calculates the power Mpow(t). The value of n is a natural number. For example, the value of n is 128. The power calculator 130 b outputs the power Mpow(t) to the ratio calculator 140.
Mpow(t)=Σm(t−j)2  (5)
The ratio calculator 140 calculates a ratio v(t) of the power Ppow(t) and the power Mpow(t). For example, the ratio calculator 140 calculates the ratio v(t) by the formula (6). The ratio calculator 140 outputs the ratio v(t) to the determination unit 150 and the gain calculator 160. Here, v(t) may be a square root of the ratio of the power Ppow(t) and the power Mpow(t).
v(t)=Mpow(t)/Ppow(t)  (6)
The determination unit 150 determines whether noise is included in the input signals Lin(t) and Rin(t) based on the ratio v(t). When the value of the ratio v(t) is greater than or equal to a predetermined threshold value, the determination unit 150 determines that noise is included in the input signals Lin(t) and Rin(t). The determination unit 150 outputs a determination result to the gain calculator 160.
The gain calculator 160 calculates a gain based on the ratio v(t). The gain calculator 160 first calculates g′(t) by the formula (7) and thereafter calculates a gain g(t) by the formula (8).
g′(t)=1−v(t)  (7)
g(t)=max(g′(t),α)  (8)
In the formula (8), α is a lower limit value greater than or equal to 0 and smaller than or equal to 1. The gain calculator 160 calculates g′(t) and thereafter calculates the larger value of g′(t) and α as the gain g(t). The gain calculator 160 outputs the gain g(t) to the noise suppression unit 170.
The gain calculator 160 may calculate the gain g(t) when noise is included in the input signals Lin(t) and Rin(t) based on the determination result of the determination unit 150. On the other hand, when noise is not included in the input signals Lin(t) and Rin(t), the gain calculator 160 may set 1 to the gain g(t) and output the gain g(t) to the noise suppression unit 170.
The noise suppression unit 170 suppresses noise by multiplying the input signals Lin(t) and Rin(t) by the gain g(t). For example, the noise suppression unit 170 generates output signals Lout(t) and Rout(t) from the input signals Lin(t) and Rin(t) and outputs the generated signals to an external apparatus. For example, the output signals Lout(t) and Rout(t) are represented by the formula (9) and the formula (10).
Lout(t)=g(t)Lin(t)  (9)
Rout(t)=g(t)Rin(t)  (10)
Next, a processing procedure of the signal processing apparatus 100 according to the first embodiment will be described. FIG. 2 is a flowchart illustrating a processing procedure of the signal processing apparatus according to the first embodiment. For example, the process illustrated in FIG. 2 is performed when input signals are received from the microphones 10 a and 10 b.
As illustrated in FIG. 2, the signal processing apparatus 100 calculates the added value p(t) obtained by adding together the input signals Lin(t) and Rin(t) of the microphones 10 a and 10 b (step S101). The signal processing apparatus 100 calculates the subtracted value m(t) obtained by subtracting the input signal Rin(t) of one microphone 10 b from the input signal Lin(t) of the other microphone 10 a (step S102).
The signal processing apparatus 100 calculates the power Ppow(t) based on the added value p(t) (step S103). The signal processing apparatus 100 calculates the power Mpow(t) based on the subtracted value m(t) (step S104).
The signal processing apparatus 100 calculates the ratio v(t) (step S105) and determines whether noise is included (step S106). The signal processing apparatus 100 calculates the gain g(t) based on the ratio v(t) (step S107). The signal processing apparatus 100 outputs the output signals Lout(t) and Rout(t) whose noise is suppressed based on the gain g(t) (step S108).
Next, effects of the signal processing apparatus 100 according to the first embodiment will be described. In the signal processing apparatus 100, the determination unit 150 determines whether noise is included in the input signals Lin(t) and Rin(t) based on the added value p(t) calculated by the adder 110 and the subtracted value m(t) calculated by the subtracter 120. Therefore, it is possible to accurately determine whether noise is included, so that noise included in the input signals can be sufficiently suppressed by using the determination result.
Generally, the lower the frequency, the stronger the correlation between the input signals. This is because the lower the frequency, the smaller the variation of waveforms in the time axis direction, so that the waveforms have similar shapes. An extreme example is a direct current. Therefore, in order to strengthen the correlation, the adder 110 sums up the input signals. On the other hand, in order to suppress the correlation, the subtracter 120 subtracts one input signal from the other input signal.
Therefore, for example, in a case where the input signals of the microphone have a correlation, such as cases of voice and noise in a driving car, a relationship of the formula (11) is established.
“power of(Lin(t)+Rin(t))”>>“power of(Lin(t)−Rin(t))”  (11)
On the other hand, in a case where the correlation between the input signals of the microphone is weak, such as case of wind hitting noise, a relationship of the formula (12) is established.
“power of(Lin(t)+Rin(t))”≈“power of(Lin(t)−Rin(t))”  (12)
Therefore, in the signal processing apparatus 100 according to the first embodiment, noise can be accurately detected by using the ratio of the “power of (Lin(t)−Rin(t))” based on the “power of (Lin(t)+Rin(t))”. Also, an appropriate gain can be calculated by using the ratio of the “power of (Lin(t)-Rin(t))” based on the “power of (Lin(t)+Rin(t))”, and a noise component included in the input signals can be suppressed by using the gain.
FIG. 3 is a diagram for explaining an effect of the present invention compared with a conventional apparatus. Signals 20A in FIG. 3 indicates a relationship between the sampling number and the gain g(t) of the conventional apparatus. Signals 20B in FIG. 3 indicates a relationship between the sampling number and the gain g(t) of the signal processing apparatus 100. Sections 21 in the signals 20A and 20B are sections including voice. When comparing the signals 20A and 20B, in the signals 20B, the gain g(t) in sections including only wind hitting noise is reduced while the gain g(t) in the sections 21 is substantially maintained at 1. Therefore, in the present invention, it is possible to turn down volume of a part of input signals including noise without turning down volume of whole input signals in voice sections.
By the way, in the signal processing apparatus 100 according to the first embodiment, the determination unit 150 determines whether noise is included based on the value of the ratio v(t). However, it is not limited to this. The determination unit 150 may obtain a difference between the Ppow(t) and the Mpow(t), and when the difference value is smaller than a predetermined threshold value, the determination unit 150 may determine that noise is included in the input signals.
The signal processing apparatus 100 may be configured by integrating the determination unit 150 and the gain calculator 160 together.
[b] Second Embodiment
Next, a signal processing apparatus according to a second embodiment will be described. FIG. 4 is a diagram illustrating a configuration of the signal processing apparatus according to the second embodiment. As illustrated in FIG. 4, a signal processing apparatus 200 is connected to the microphones 10 a and 10 b. The microphones 10 a and 10 b are spaced apart from each other by a predetermined distance. The description about the microphones 10 a and 10 b is the same as that in the first embodiment.
The signal processing apparatus 200 includes a delay detector 201 and delay devices 202 a and 202 b. The signal processing apparatus 200 also includes an adder 210, a subtracter 220, and power calculators 230 a and 230 b. The signal processing apparatus 200 also includes a ratio calculator 240, a determination unit 250, a gain calculator 260, and a noise suppression unit 270.
The delay detector 201 calculates a correlation coefficient c(d) between the input signal Lin(t) and the input signal Rin(t) by the formula (13). The delay detector 201 changes a delay amount d and detects a delay amount dmax by which the value of correlation coefficient c(d) is the maximum.
c(d)=ΣLin(t)Rin(t−d)/((ΣLin(t)2)1/2(ΣRin(t−d)2)1/2)  (13)
After detecting the dmax, the delay detector 201 calculates a delay amount dL applied to the input signal from the microphone 10 a and a delay amount dR applied to the input signal from the microphone 10 b in order to synchronize the input signals inputted from the microphones 10 a and 10 b. A calculation example of the delay amounts dL and dR will be described below.
When the value of the dmax is greater than or equal to 0, the delay detector 201 sets the value of dL to 0 and sets the value of dR to the value of the dmax. Then, the delay detector 201 outputs the dL to the delay device 202 a and outputs the dR to the delay device 202 b.
On the other hand, when the value of the dmax is smaller than 0, the delay detector 201 sets the value of dL to the absolute value of the dmax and sets the value of dR to 0. Then, the delay detector 201 outputs the dL to the delay device 202 a and outputs the dR to the delay device 202 b.
The delay device 202 a performs a delay process of the input signal Lin(t) from the microphone 10 a. The delay device 202 a outputs an input signal Lin(t−dL) obtained by performing a delay process on the input signal Lin(t) to the adder 210 and the subtracter 220.
The delay device 202 b performs a delay process of the input signal Rin(t) from the microphone 10 b. The delay device 202 b outputs an input signal Rin(t−dR) obtained by performing a delay process on the input signal Rin(t) to the adder 210 and the subtracter 220.
The adder 210 calculates an added value p(t) by adding together the input signals Lin(t−dL) and Rin(t−dR) whose delay amounts are adjusted. The adder 210 outputs the added value p(t) to the power calculator 230 a.
The subtracter 220 calculates an subtracted value m(t) by subtracting the input signal Rin(t−dR) from the input signal Lin(t−dL). The subtracter 220 outputs the subtracted value m(t) to the power calculator 230 b.
The descriptions about the power calculators 230 a and 230 b, the ratio calculator 240, the determination unit 250, the gain calculator 260, and the noise suppression unit 270 are the same as those of the power calculators 130 a and 130 b, the ratio calculator 140, the determination unit 150, the gain calculator 160, and the noise suppression unit 170 illustrated in FIG. 1.
Next, a processing procedure of the signal processing apparatus 200 according to the second embodiment will be described. FIG. 5 is a flowchart illustrating the processing procedure of the signal processing apparatus according to the second embodiment. For example, the process illustrated in FIG. 5 is performed when input signals are received from the microphones 10 a and 10 b.
The signal processing apparatus 200 detects the maximum value of the correlation coefficient c(d) between the input signal Lin(t) and the input signal Rin(t) and calculates the delay amounts dL and dR for synchronization (step S201). The signal processing apparatus 200 calculates the p(t) by performing synchronous addition (step S202) and calculates the m(t) by performing synchronous subtraction (step S203).
The signal processing apparatus 200 calculates the power Ppow(t) based on the added value p(t) (step S204). The signal processing apparatus 200 calculates the power Mpow(t) based on the subtracted value m(t) (step S205).
The signal processing apparatus 200 calculates the ratio v(t) (step S206) and determines whether noise is included (step S207). The signal processing apparatus 200 calculates the gain g(t) based on the ratio v(t) (step S208). The signal processing apparatus 200 outputs the output signals Lout(t) and Rout(t) whose noise is suppressed based on the gain g(t) (step S209).
Next, effects of the signal processing apparatus 200 according to the second embodiment will be described. In the signal processing apparatus 200, the delay detector 201 calculates the delay amounts dL and dR and the delay devices 202 a and 202 b synchronize the input signals. In the signal processing apparatus 200, the determination unit 250 determines whether noise is included in the input signals Lin(t) and Rin(t) based on the added value p(t) calculated by the adder 210 and the subtracted value m(t) calculated by the subtracter 220. Therefore, even if the timings when voice of a user is collected by the microphones 10 a and 10 b are different from each other, the input signals can be synchronized by adjusting the delay amounts. Thus, it is possible to accurately determine whether noise is included in a direction of a user whose voice is desired to be recorded, so that noise included in the input signals can be suppressed by using the determination result.
[c] Third Embodiment
Next, a signal processing apparatus according to the third embodiment will be described. FIG. 6 is a diagram illustrating a configuration of the signal processing apparatus according to the third embodiment. As illustrated in FIG. 6, a signal processing apparatus 300 is connected to the microphones 10 a and 10 b. The microphones 10 a and 10 b are spaced apart from each other by a predetermined distance. The description about the microphones 10 a and 10 b is the same as that in the first embodiment.
The signal processing apparatus 300 includes FFTs (Fast Fourier Transforms) 301 a and 301 b, an adder 310, a subtracter 320, and power calculators 330 a and 330 b. The signal processing apparatus 300 also includes a ratio calculator 340, a determination unit 350, a gain calculator 360, a noise suppression unit 370, and IFFTs (Inverse FFTs) 371 a and 371 b.
The FFT 301 a positions a Hanning window with 50% overlap on the input signal Lin(t) acquired from the microphone 10 a and converts the input signal Lin(t) into a signal on the frequency axis by fast Fourier transform. The input signal Lin(t) converted into a signal on the frequency axis is represented as LIN(i, f). Here, i is a number of an analysis frame on which FFT is performed and f indicates the frequency. The FFT 301 a outputs the LIN(i, f) to the adder 310, the subtracter 320, and the noise suppression unit 370.
The FFT 301 b positions a Hanning window with 50% overlap on the input signal Rin(t) acquired from the microphone 10 b and converts the input signal Rin(t) into a signal on the frequency axis by fast Fourier transform. The input signal Rin(t) converted into a signal on the frequency axis is represented as RIN(i, f). The FFT 301 b outputs the RIN(i, f) to the adder 310, the subtracter 320, and the noise suppression unit 370. The FFTs 301 a and 301 b are an example of a frequency converter.
The adder 310 is a processing unit which calculates an added value p(i, f) by adding the input signal LIN(i, f) and the input signal RIN(i, f) together. The added value p(i, f) is represented by the formula (14). The adder 310 outputs the added value p(i, f) to the power calculator 330 a.
p(i, f)=LIN(i, f)+RIN(i, f)  (14)
The subtracter 320 calculates a subtracted value m(i, f) by subtracting the input signal RIN(i, f) from the input signal LIN(i, f). The subtracted value m(i, f) is represented by the formula (15). The subtracter 320 outputs the subtracted value m(i, f) to the power calculator 330 b.
m(i, f)=LIN(i, f)−RIN(i, f)  (15)
The power calculator 330 a calculates a power Ppow(i, f) by summing up squared values of the added value p(i, f) of different frame numbers. The power Ppow(i, f) is represented by the formula (16). The power calculator 330 a sequentially changes the value of j from 1 to n and calculates the power Ppow(i, f). The value of n is a natural number. For example, the value of n is 128. The power calculator 330 a outputs the power Ppow(i, f) to the ratio calculator 340.
Ppow(i, f)=Σp(i−j, f)  (16)
The power calculator 330 b calculates a power Mpow(i, f) by summing up squared values of the subtracted value m(i, f) of different frame numbers. The power Mpow(i, f) is represented by the formula (17). The power calculator 330 b sequentially changes the value of j from 1 to n and calculates the power Mpow(i, f). The value of n is a natural number. For example, the value of n is 128. The power calculator 330 b outputs the power Mpow(i, f) to the ratio calculator 340.
Mpow(i, f)=Σm(i−j, f)  (17)
The ratio calculator 340 calculates a ratio v(i, f) of the power Ppow(i, f) and the power Mpow(i, f). For example, the ratio calculator 340 calculates the ratio v(i, f) by the formula (18). The ratio calculator 340 outputs the ratio v(i, f) to the determination unit 350 and the gain calculator 360.
v(i, f)=Mpow(i, f)/Ppow(i, f)  (18)
The determination unit 350 determines whether noise is included in the input signals LIN(i, f) and RIN(i, f) based on the ratio v(i, f). When the value of the ratio v(i, f) is greater than or equal to a predetermined threshold value, the determination unit 350 determines that noise is included in the input signals LIN(i, f) and RIN(i, f). The determination unit 350 outputs a determination result to the gain calculator 360.
The gain calculator 360 calculates a gain based on the ratio v(i, f). The gain calculator 360 first calculates g′(i, f) by the formula (19) and thereafter calculates a gain g(i, f) by the formula (20).
g′(i, f)=1−v(i, f)  (19)
g(i, f)=max(g′(i, f),α)  (20)
In the formula (20), α is a lower limit value greater than or equal to 0 and smaller than or equal to 1. The gain calculator 360 calculates g′(i, f) and thereafter calculates the larger value of g′(i, f) and α as the gain g(i, f). The gain calculator 360 outputs the gain g(i, f) to the noise suppression unit 370.
The gain calculator 360 may calculate the gain g(i, f) when noise is included in the input signals LIN(i, f) and RIN(i, f) based on the determination result of the determination unit 350. On the other hand, when noise is not included in the input signals LIN(i, f) and RIN(i, f), the gain calculator 360 may set 1 to the gain g(i, f) and output the gain g(i, f) to the noise suppression unit 370.
The noise suppression unit 370 suppresses noise by multiplying the input signals LIN(i, f) and RIN(i, f) by the gain g(i, f). For example, the noise suppression unit 370 generates output signals LOUT(i, f) and ROUT (i, f) from the input signals LIN(i, f) and RIN(i, f) and outputs the generated signals to the IFFTs 371 a and 371 b. For example, the output signals LOUT(i, f) and ROUT (i, f) are represented by the formulas (21) and (22).
LOUT(i, f)=g(i, f)LIN(i, f)  (21)
ROUT(i, f)=g(i, f)RIN(i, f)  (22)
The IFFT 371 a is a processing unit which generates a signal Lin(t) on the time axis by performing an inverse Fourier transform and 50% overlap addition on the LOUT(i, f). The IFFT 371 a outputs the output signal Lin(t) to an external apparatus.
The IFFT 371 b is a processing unit which generates a signal Rin(t) on the time axis by performing an inverse Fourier transform and 50% overlap addition on the ROUT(i, f). The IFFT 371 b outputs the output signal Rin(t) to an external apparatus.
Next, a processing procedure of the signal processing apparatus 300 according to the third embodiment will be described. FIG. 7 is a flowchart illustrating the processing procedure of the signal processing apparatus according to the third embodiment. For example, the process illustrated in FIG. 7 is performed when input signals are received from the microphones 10 a and 10 b.
As illustrated in FIG. 7, the signal processing apparatus 300 calculates the LIN(i, f) and the RIN(i, f) by performing a Fourier transform on the input signals Lin(t) and Rin(t) of the microphones (step S301). The signal processing apparatus 300 calculates the added value p(i, f) obtained by adding together the input signals LIN(i, f) and RIN(i, f) of the microphones (step S302).
The signal processing apparatus 300 calculates the subtracted value m(i, f) obtained by subtracting the input signal RIN(i, f) of one microphone from the input signal LIN(i, f) of the other microphone (step S303). The signal processing apparatus 300 calculates the power Ppow(i, f) based on the added value p(i, f) (step S304).
The signal processing apparatus 300 calculates the power Mpow(i, f) based on the subtracted value m(i, f) (step S305). The signal processing apparatus 300 calculates the ratio v(i, f) (step S306) and determines whether noise is included (step S307).
The signal processing apparatus 300 calculates the gain g(i, f) based on the ratio v(i, f) (step S308). The signal processing apparatus 300 outputs the output signals LOUT(i, f) and ROUT(i, f) whose noise is suppressed based on the gain g(i, f) (step S309). The signal processing apparatus 300 performs an inverse Fourier transform on the output signals LOUT(i, f) and ROUT(i, f) and outputs Lout(t) and Rout(t) (step S310).
Next, effects of the signal processing apparatus 300 according to the third embodiment will be described. The signal processing apparatus 300 performs a Fourier transform on the input signals Lin(t) and Rin(t) and determines whether there is noise at each frequency. Then, the signal processing apparatus 300 calculates the gain g(i, f) at each frequency and multiplies the input signals LIN(i, f) and RIN(i, f) at each frequency by the gain g(i, f). Therefore, noise at each frequency can be suppressed.
[d] Fourth Embodiment
The processes of the aforementioned signal processing apparatuses 100 to 300 are an example. Hereinafter, another process of the signal processing apparatuses of the present invention will be described as a fourth embodiment. The process according to the fourth embodiment will be described with reference to the configuration diagram in FIG. 1.
Another process of the gain calculator 160 will be described. Although the gain calculator 160 calculates the gain g(t) by using the formula (7) and the formula (8), it is not limited to this. The gain calculator 160 may calculate the gain g(t) by using a decision table indicating a relationship between the gain g(t) and the ratio v(t) for each distance between the microphones 10 a and 10 b.
FIG. 8 is a diagram for explaining the other process of the gain calculator. For example, the gain calculator 160 defines that when the distance between the microphones 10 a and 10 b is 4.2 cm, the relationship between the gain g(t) and the ratio v(t) is a relationship changing as illustrated by a straight line 30A in FIG. 8. The relationship illustrated by the straight line 30A corresponds to the relationship of the formula (7).
On the other hand, the gain calculator 160 defines that when the distance between the microphones 10 a and 10 b is smaller than 4.2 cm, the relationship changes as illustrated by a curved line 30B in FIG. 8. In other words, the gain calculator 160 sets the change rate of the gain g(t) larger than that indicated by the straight line 30A when the value of the ratio v(t) is about 1 to 0.8. The gain calculator 160 performs the process as described above, so that it is possible to accurately suppress noise corresponding to the change of characteristics of the input signals caused by the difference of the distance between the microphones.
The gain calculator 160 may acquire information of the distance between the microphones 10 a and 10 b in any manner. A user may input the distance into the signal processing apparatus 100 by using an input device.
Another process of the power calculator 130 a will be described. The power calculator 130 a obtains the power Ppow(t) based on the formula (4). However, instead of the power Ppow(t), an average Pamp(t) of the absolute values may be calculated. For example, the power calculator 130 a obtains the average of the absolute values by the formula (23).
Pamp(t)=Σ|p(t−j)|  (23)
Similarly, the power calculator 130 b may calculate an average Mamp(t) of the absolute values instead of the power Mpow(t). For example, the power calculator 130 b obtains the average of the absolute values by the formula (24).
Mamp(t)=Σ|m(t−j)|  (24)
It is known that when the average of the absolute values is obtained, the processing load of the computer is smaller than when the power is obtained. Therefore, when it is configured so that the power calculators 130 a and 130 b calculate the average of the absolute values instead of the power, the cost of the signal processing apparatus 100 can be reduced.
By the way, the signal processing apparatus 100 may suppress noise by using microphones 10 c and 10 d not illustrated in the drawings in addition to the pair of microphones 10 a and 10 b. For example, the signal processing apparatus 100 calculates the ratio v(t) from the microphones 10 a and 10 b by the same process as that in the first embodiment. The v(t) calculated from the microphones 10 a and 10 b is defined as v1(t).
Also, the ratio v(t) is calculated from the microphones 10 c and 10 d by the same process as that in the first embodiment. The v(t) calculated from the microphones 10 c and 10 d is defined as v2(t). When both the v1(t) and v2(t) are greater than a predetermined threshold value, the signal processing apparatus 100 may adjust the input signals Lin(t) and Rin(t) by the gain g(t).
For example, the signal processing apparatus 100 may obtain g′(t) by the formula (25) or the formula (26). The processes after calculating the g′(t) is the same as that in the first embodiment. The g′(t) may be obtained by subtracting the average value of the v1(1) and v2(2) from 1.
g′(t)=1−v1(t)  (25)
g′(t)=1−v2(t)  (26)
In this way, the gain g(t) is calculated by using the microphones 10 a to 10 d, so that it is possible to accurately suppress noise of the input signals even when there are a plurality of users.
The processing units included in the signal processing apparatuses 100 to 300 described in the first to the fourth embodiments correspond to integrated devices such as, for example, ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array). Also, the processing units correspond to electronic circuits such as CPU and MPU (Micro Processing Unit).
Next, an example of a computer that executes a signal processing program which realizes the same function as that of the signal processing apparatuses 100 to 300 described in the embodiments will be described. FIG. 9 is a diagram illustrating an example of the computer that executes the signal processing program.
As illustrated in FIG. 9, a computer 400 includes a CPU 401 that performs various calculation processes, an input device 402 that receives input of data from a user, and a display 403. The computer 400 also includes a reading device 404 that reads a program and the like from a storage medium and an interface device 405 that transmits and receives data to and from another computer through a network. The computer 400 also includes microphones 406 a and 406 b. The computer 400 also includes a RAM 407 that temporarily stores various information and a hard disk device 408. The devices 401 to 408 are connected to a bus 409.
The hard disk device 408 includes, for example, an addition program 408 a, a subtraction program 408 b, a power calculation program 408 c, a ratio calculation program 408 d, a determination program 408 e, a gain calculation program 408 f, and a noise suppression program 408 g. The CPU 401 reads the programs 408 a to 408 g and develops the programs in the RAM 407.
The addition program 408 a functions as an addition process 407 a. The subtraction program 408 b functions as a subtraction process 407 b. The power calculation program 408 c functions as a power calculation process 407 c. The ratio calculation program 408 d functions as a ratio calculation process 407 d. The determination program 408 e functions as a determination process 407 e. The gain calculation program 408 f functions as a gain calculation process 407 f. The noise suppression program 408 g functions as a noise suppression process 407 g.
For example, the addition process 407 a corresponds to the adder 110. The subtraction process 407 b corresponds to the subtracter 120. The power calculation process 407 c corresponds to the power calculators 130 a and 130 b. The ratio calculation process 407 d corresponds to the ratio calculator 140. The determination process 407 e corresponds to the determination unit 150. The gain calculation process 407 f corresponds to the gain calculator 160. The noise suppression process 407 g corresponds to the noise suppression unit 170.
The programs 408 a to 408 g need not necessarily be stored in the hard disk device 408 from the beginning. For example, the programs are stored in a “portable physical medium” such as a flexible disk (FD), a CD-ROM, a DVD disk, a magneto-optical disk, and an IC card which are inserted in the computer 400. The computer 400 may read the programs 408 a to 408 g from these media and execute the programs. The programs of the signal processing apparatuses 200 and 300 described in the second to the fourth embodiments are executed by the computer 400 in the same manner as the programs of the signal processing apparatus 100.
According to the disclosed signal processing apparatus, there is an effect that noise included in the input signal can be suppressed.
All examples and conditional language recited herein are intended for pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

Claims (10)

What is claimed is:
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;
a ratio calculator that calculates a ratio of the subtracted value to the added value;
a gain calculator that calculates a 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;
a determination unit that determines noise being included in the input signals when a difference between the added value and the subtracted value is less than a threshold value; and
a noise suppression unit that suppresses noise of the input signals based on the gain calculated by the gain calculator.
2. The signal processing apparatus according to claim 1,
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.
3. 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.
4. 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.
5. The signal processing apparatus according to claim 1, 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.
6. The signal processing apparatus according to claim 1, wherein the ratio calculator calculates a ratio of an absolute value of the subtracted value to an absolute value of the added value.
7. The signal processing apparatus according to claim 1, 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.
8. The signal processing apparatus according to claim 1, wherein the gain calculator calculates the gain based on a formula g(t)=1−v(t), g(t) indicating the gain, v(t) indicating ratio when a distance between the microphones is 4.2 cm, and calculates the gain based on a decision table which sets a change rate of the gain different from the change rate of the gain calculated by the formula when the distance between the microphones is smaller than 4.2 cm.
9. 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;
calculating a ratio of the subtracted value to the added value;
calculating a 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;
determining noise being included in the input signals when a difference between the added value and the subtracted value is less than a threshold value; and
suppressing noise of the input signals based on the gain calculated at the calculating the gain.
10. A non-transitory 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;
calculating a ratio of the subtracted value to the added value;
calculating a 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;
determining noise being included in the input signals when a difference between the added value and the subtracted value is less than a threshold value; and
suppressing noise of the input signals based on the gain calculated at the calculating the gain.
US13/685,079 2011-12-15 2012-11-26 Signal processing apparatus and signal processing method Expired - Fee Related US9271075B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011-274742 2011-12-15
JP2011274742A JP5929154B2 (en) 2011-12-15 2011-12-15 Signal processing apparatus, signal processing method, and signal processing program

Publications (2)

Publication Number Publication Date
US20130156221A1 US20130156221A1 (en) 2013-06-20
US9271075B2 true US9271075B2 (en) 2016-02-23

Family

ID=47429554

Family Applications (1)

Application Number Title Priority Date Filing Date
US13/685,079 Expired - Fee Related US9271075B2 (en) 2011-12-15 2012-11-26 Signal processing apparatus and signal processing method

Country Status (3)

Country Link
US (1) US9271075B2 (en)
EP (1) EP2608201B1 (en)
JP (1) JP5929154B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220199100A1 (en) * 2020-12-21 2022-06-23 Qualcomm Incorporated Spatial audio wind noise detection

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9516418B2 (en) * 2013-01-29 2016-12-06 2236008 Ontario Inc. Sound field spatial stabilizer
US9106196B2 (en) * 2013-06-20 2015-08-11 2236008 Ontario Inc. Sound field spatial stabilizer with echo spectral coherence compensation
US9271100B2 (en) 2013-06-20 2016-02-23 2236008 Ontario Inc. Sound field spatial stabilizer with spectral coherence compensation
US9099973B2 (en) * 2013-06-20 2015-08-04 2236008 Ontario Inc. Sound field spatial stabilizer with structured noise compensation
CN104282303B (en) 2013-07-09 2019-03-29 威盛电子股份有限公司 The method and its electronic device of speech recognition are carried out using Application on Voiceprint Recognition
EP3163903B1 (en) * 2015-10-26 2019-06-19 Nxp B.V. Accoustic processor for a mobile device
JP6967353B2 (en) * 2017-02-15 2021-11-17 三菱重工サーマルシステムズ株式会社 Air conditioner and air conditioning system

Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4334740A (en) 1978-09-12 1982-06-15 Polaroid Corporation Receiving system having pre-selected directional response
JPH05308696A (en) 1992-05-06 1993-11-19 Matsushita Electric Ind Co Ltd Wind noise sensor
JP2001313992A (en) 2000-04-28 2001-11-09 Nippon Telegr & Teleph Corp <Ntt> Sound pickup device and sound pickup method
US20030120485A1 (en) * 2001-12-21 2003-06-26 Fujitsu Limited Signal processing system and method
US20030147538A1 (en) * 2002-02-05 2003-08-07 Mh Acoustics, Llc, A Delaware Corporation Reducing noise in audio systems
EP1450353A1 (en) 2003-02-21 2004-08-25 Harman Becker Automotive Systems-Wavemakers, Inc. System for suppressing wind noise
JP2004289762A (en) 2003-01-29 2004-10-14 Toshiba Corp Method of processing sound signal, and system and program therefor
JP2005110127A (en) 2003-10-01 2005-04-21 Canon Inc Wind noise detecting device and video camera with wind noise detecting device
JP2006237816A (en) 2005-02-23 2006-09-07 Sanyo Electric Co Ltd Arithmetic unit, sound pickup device and signal processing program
WO2007059255A1 (en) * 2005-11-17 2007-05-24 Mh Acoustics, Llc Dual-microphone spatial noise suppression
EP1940196A1 (en) 2006-12-25 2008-07-02 Sony Corporation Audio signal processing apparatus, audio signal processing method and imaging apparatus
US20080175407A1 (en) * 2007-01-23 2008-07-24 Fortemedia, Inc. System and method for calibrating phase and gain mismatches of an array microphone
US20080212794A1 (en) * 2007-03-01 2008-09-04 Canon Kabushiki Kaisha Audio processing apparatus
JP2008245254A (en) 2007-03-01 2008-10-09 Canon Inc Audio processing apparatus
US20080260175A1 (en) 2002-02-05 2008-10-23 Mh Acoustics, Llc Dual-Microphone Spatial Noise Suppression
JP2009005133A (en) 2007-06-22 2009-01-08 Sanyo Electric Co Ltd Wind noise reducing apparatus and electronic device with the wind noise reducing apparatus
US20090175466A1 (en) * 2002-02-05 2009-07-09 Mh Acoustics, Llc Noise-reducing directional microphone array
US20090226006A1 (en) * 2007-10-19 2009-09-10 Sennheiser Electronic Corporation Microphone device
JP2010028307A (en) 2008-07-16 2010-02-04 Sony Corp Noise reduction device, method, and program
JP2010252375A (en) 2010-06-16 2010-11-04 Funai Electric Co Ltd Voice signal transmitting/receiving apparatus

Patent Citations (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4334740A (en) 1978-09-12 1982-06-15 Polaroid Corporation Receiving system having pre-selected directional response
JPH05308696A (en) 1992-05-06 1993-11-19 Matsushita Electric Ind Co Ltd Wind noise sensor
JP2001313992A (en) 2000-04-28 2001-11-09 Nippon Telegr & Teleph Corp <Ntt> Sound pickup device and sound pickup method
US7203640B2 (en) 2001-12-21 2007-04-10 Fujitsu Limited System and method for determining an intended signal section candidate and a type of noise section candidate
US20030120485A1 (en) * 2001-12-21 2003-06-26 Fujitsu Limited Signal processing system and method
US20030147538A1 (en) * 2002-02-05 2003-08-07 Mh Acoustics, Llc, A Delaware Corporation Reducing noise in audio systems
US20090175466A1 (en) * 2002-02-05 2009-07-09 Mh Acoustics, Llc Noise-reducing directional microphone array
US20080260175A1 (en) 2002-02-05 2008-10-23 Mh Acoustics, Llc Dual-Microphone Spatial Noise Suppression
JP2004289762A (en) 2003-01-29 2004-10-14 Toshiba Corp Method of processing sound signal, and system and program therefor
EP1450353A1 (en) 2003-02-21 2004-08-25 Harman Becker Automotive Systems-Wavemakers, Inc. System for suppressing wind noise
JP2005110127A (en) 2003-10-01 2005-04-21 Canon Inc Wind noise detecting device and video camera with wind noise detecting device
JP2006237816A (en) 2005-02-23 2006-09-07 Sanyo Electric Co Ltd Arithmetic unit, sound pickup device and signal processing program
WO2007059255A1 (en) * 2005-11-17 2007-05-24 Mh Acoustics, Llc Dual-microphone spatial noise suppression
EP1940196A1 (en) 2006-12-25 2008-07-02 Sony Corporation Audio signal processing apparatus, audio signal processing method and imaging apparatus
US20080175407A1 (en) * 2007-01-23 2008-07-24 Fortemedia, Inc. System and method for calibrating phase and gain mismatches of an array microphone
US20080212794A1 (en) * 2007-03-01 2008-09-04 Canon Kabushiki Kaisha Audio processing apparatus
JP2008245254A (en) 2007-03-01 2008-10-09 Canon Inc Audio processing apparatus
US8068620B2 (en) 2007-03-01 2011-11-29 Canon Kabushiki Kaisha Audio processing apparatus
JP2009005133A (en) 2007-06-22 2009-01-08 Sanyo Electric Co Ltd Wind noise reducing apparatus and electronic device with the wind noise reducing apparatus
US20090226006A1 (en) * 2007-10-19 2009-09-10 Sennheiser Electronic Corporation Microphone device
JP2010028307A (en) 2008-07-16 2010-02-04 Sony Corp Noise reduction device, method, and program
JP2010252375A (en) 2010-06-16 2010-11-04 Funai Electric Co Ltd Voice signal transmitting/receiving apparatus

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Extended European Search Report dated Jun. 14, 2013 for corresponding European Application No. 12194568.7.
Japanese Office Action mailed Apr. 21, 2015 for corresponding Japanese Patent Application No. 2011-274742, with Partial English Translation, 4 pages.
Japanese Office Action mailed Sep. 1, 2015 for corresponding Japanese Patent Application No. 2011-274742, with Partial English Translation, 4 pages.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220199100A1 (en) * 2020-12-21 2022-06-23 Qualcomm Incorporated Spatial audio wind noise detection
US11721353B2 (en) * 2020-12-21 2023-08-08 Qualcomm Incorporated Spatial audio wind noise detection

Also Published As

Publication number Publication date
EP2608201A3 (en) 2013-07-17
JP2013125197A (en) 2013-06-24
JP5929154B2 (en) 2016-06-01
US20130156221A1 (en) 2013-06-20
EP2608201A2 (en) 2013-06-26
EP2608201B1 (en) 2022-06-01

Similar Documents

Publication Publication Date Title
US9271075B2 (en) Signal processing apparatus and signal processing method
KR100883712B1 (en) Method of estimating sound arrival direction, and sound arrival direction estimating apparatus
US9113241B2 (en) Noise removing apparatus and noise removing method
US10679641B2 (en) Noise suppression device and noise suppressing method
US9460731B2 (en) Noise estimation apparatus, noise estimation method, and noise estimation program
US8891780B2 (en) Microphone array device
KR101610161B1 (en) System and method for speech recognition
KR20120080409A (en) Apparatus and method for estimating noise level by noise section discrimination
CN105103230B (en) Signal processing device, signal processing method, and signal processing program
EP2920949B1 (en) Echo suppression
JP2014122939A (en) Voice processing device and method, and program
US9754606B2 (en) Processing apparatus, processing method, program, computer readable information recording medium and processing system
US9779754B2 (en) Speech enhancement device and speech enhancement method
US10014838B2 (en) Gain adjustment apparatus and gain adjustment method
US8856001B2 (en) Speech sound detection apparatus
JP6638248B2 (en) Audio determination device, method and program, and audio signal processing device
US10706870B2 (en) Sound processing method, apparatus for sound processing, and non-transitory computer-readable storage medium
KR101509649B1 (en) Method and apparatus for detecting sound object based on estimation accuracy in frequency band
US11004463B2 (en) Speech processing method, apparatus, and non-transitory computer-readable storage medium for storing a computer program for pitch frequency detection based upon a learned value
US10636438B2 (en) Method, information processing apparatus for processing speech, and non-transitory computer-readable storage medium
US11227625B2 (en) Storage medium, speaker direction determination method, and speaker direction determination device
CN114495961A (en) Voice noise reduction method and device, electronic equipment and computer readable storage medium
CN115691532A (en) Wind noise pollution range estimation method, wind noise pollution range suppression device, medium and terminal
JP2014095769A (en) Utterance zone determination device, utterance zone determination method, and utterance zone determination program

Legal Events

Date Code Title Description
AS Assignment

Owner name: FUJITSU LIMITED, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MATSUO, NAOSHI;REEL/FRAME:029451/0783

Effective date: 20121105

STCF Information on status: patent grant

Free format text: PATENTED CASE

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 4

AS Assignment

Owner name: SIA SYNCROSOFT, LATVIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HARDER, WULF;PEETERS, BERND;RESAS, UWE;AND OTHERS;REEL/FRAME:052718/0775

Effective date: 20051031

Owner name: WHITECRYPTION CORPORATION, DELAWARE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SIA WHITECRYPTION;REEL/FRAME:052718/0834

Effective date: 20110602

Owner name: SIA WHITECRYPTION, LATVIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SIA SYNCROSOFT;REEL/FRAME:052719/0825

Effective date: 20100726

FEPP Fee payment procedure

Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

LAPS Lapse for failure to pay maintenance fees

Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY