JP2018042025A - Audio signal processing device, audio signal processing method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an audio signal processing device capable of reducing wind noise while preventing sound quality from being reduced.SOLUTION: An audio signal processing device comprises: generation means which generates in-phase components and reverse-phase components of multiple audio signals; first and second extraction means which extract signals of a first frequency band from signals of the in-phase components and the reverse-phase components; third and fourth extraction means for extracting signals of a second frequency band higher than the first frequency band from the signals of the in-phase components and the reverse-phase components; first differential means which outputs a differential between the signals that are extracted by the first and second extraction means; second differential means which outputs a differential between the signals that are extracted by the third and fourth extraction means; first and second integration means which integrate the differentials that are outputted by the first and second differential means; and control means which performs control in such a manner that wind noise reduction processing is performed on multiple audio signals, in accordance with the integration values of the first and second integration means.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an audio signal processing device, an audio signal processing method, and a program.

  A technique for reducing noise (hereinafter referred to as wind noise) generated by wind blown near a microphone in an audio processing apparatus such as a video camera is known (see Patent Document 1). A normal audio signal contains many in-phase components (in-phase components) in the left channel (Lch) and the right channel (Rch), whereas wind noise is a low frequency band in the left channel and the right channel. Contains many anti-phase components (anti-phase components). Therefore, in Patent Document 1, wind noise reduction processing is performed based on the low frequency component of the difference between the left channel and the right channel.

JP-A-5-14989

  However, in addition to wind noise, there is noise that includes many antiphase components in a low frequency band. That is noise (hereinafter referred to as touch sound) generated by vibration when the user touches the camera body (housing). For this reason, since the touch sound and the wind noise cannot be discriminated only by including the low frequency of the anti-phase component, there is a possibility that the wind noise reduction process may be performed even though the touch sound is actually the touch sound. Since the touch sound converges in a relatively short time, there is a problem that the sound quality deteriorates when the wind noise reduction process is performed.

  An object of the present invention is to provide an audio signal processing device, an audio signal processing method, and a program capable of reducing wind noise while preventing deterioration in sound quality.

  An audio signal processing device according to the present invention includes an in-phase component generation unit that generates in-phase components of a plurality of audio signals, an anti-phase component generation unit that generates anti-phase components of the plurality of audio signals, and an in-phase component signal A first extraction means for extracting a signal in the first frequency band, a second extraction means for extracting the signal in the first frequency band out of the signals in the anti-phase component, and the in-phase component A third extraction means for extracting a signal in a second frequency band higher than the first frequency band in the signal; and a signal in the second frequency band in the signal of the negative phase component. A fourth extraction unit; a first difference unit that outputs a difference between the signal extracted by the first extraction unit and the signal extracted by the second extraction unit; and the third extraction unit. Extracted by the extracted signal and the fourth extraction means Second difference means for outputting the difference from the received signal, first integration means for integrating the difference output by the first difference means, and second for integrating the difference output by the second difference means. And the integration value of the first integration means is equal to or greater than a first threshold, and the difference between the integration value of the first integration means and the integration value of the second integration means is a second value. And control means for controlling to perform wind noise reduction processing on the plurality of audio signals when the threshold is equal to or greater than the threshold value.

  According to the present invention, it is possible to reduce wind noise while preventing deterioration in sound quality.

It is a figure which shows the structural example of the imaging device by this embodiment. It is a figure which shows the structural example of an audio | voice processing part. It is a spectrum figure which shows frequency distribution of a touch sound. It is a spectrum figure which shows the frequency distribution of a wind noise. It is a figure which shows the operation state of a wind noise reduction process. It is a flowchart which shows the reduction process of a wind noise. It is a flowchart which shows the reduction process of a wind noise.

  FIG. 1 is a diagram illustrating a configuration example of an imaging apparatus 100 according to an embodiment of the present invention. The imaging device 100 is an audio signal processing device. The imaging device 100 can be applied to a smart phone, a tablet, an industrial camera, a medical camera, and the like in addition to a digital camera and a video camera. The imaging apparatus 100 includes a CPU 102, a program ROM 103, a memory 104, a display 105, an operation unit 106, an imaging unit 107, an image processing unit 108, a sound collecting unit 109, an audio processing unit 110, and A recording unit 111 is included. In addition, the imaging apparatus 100 includes a battery, a recording medium drive, and other input / output terminals. Moreover, the imaging device 100 has a housing, and each of the functional blocks is arranged in the housing. Further, vibration generated when the user touches the casing of the imaging apparatus 100 is captured by the sound collection unit 109 as a touch sound.

  The bus 101 is a general-purpose bus for inputting / outputting various data, control signals, instruction signals, and the like to each block of the imaging apparatus 100. The CPU 102 is a central processing unit that controls the operation of the imaging apparatus 100. The CPU 102 executes various programs to be described later regarding the control of the voice processing unit 110, and performs display control of the display 105, reception processing of the operation unit 106, and the like. The program ROM 103 stores data and operation processing procedures of the CPU 102 (for example, programs such as start-up processing of the imaging apparatus 100, basic input / output processing, and each processing described later).

  The memory 104 is used as a work area for the CPU 102. The display 105 is a display unit for providing a graphic user interface (GUI). The operation unit 106 is a plurality of switches arranged on the housing of the imaging apparatus 100, or a resistive film type or capacitive type touch panel arranged on the surface of the display 105. The touch panel can instruct various operation inputs to the CPU 102 by combining the display image of the display 105 and the detection area of the touch panel.

  The image capturing unit 107 controls the light amount of the optical image of the subject captured by the lens using an aperture, converts the optical image into an image signal using an image sensor such as a CCD sensor or a CMOS sensor, performs analog-digital conversion, and performs a signal processing unit. To 108. The image processing unit 108 executes image processing necessary for image recording / playback, and is a microcomputer equipped with a program for executing the following processing. Further, the image processing unit 108 may execute the following processing as a part of the function of the CPU 102. The image processing unit 108 temporarily stores the digital image signal acquired from the imaging unit 107 in an internal memory, and performs image quality adjustment processing for adjusting white balance, color, brightness, and the like based on the settings. Further, the image processing unit 108 changes the image size such as the number of pixels and aspect ratio of the image obtained from the imaging unit 107. Further, the image processing unit 108 generates moving image data from the image signals of a plurality of frames that have undergone image quality adjustment processing.

  The sound collection unit 109 captures the sound around the imaging apparatus 100 using a built-in microphone, converts the acquired analog sound signal into a digital signal, and transmits the digital signal to the sound processing unit 110. The sound collection unit 109 outputs audio signals of the left channel (Lch) and the right channel (Rch). The audio processing unit 110 executes a process necessary for recording and reproducing audio, and is a microcomputer equipped with a program for executing the following process. Further, the audio processing unit 110 may execute the following processing as a part of the function of the CPU 102.

  The sound processing unit 110 temporarily stores the digital sound signal transmitted from the sound collection unit 109 in an internal memory, and relates to sound such as effect processing for imparting special effects to the sound, level optimization processing, noise reduction processing, and the like. Process. The audio processing unit 110 transmits the audio signal for which the above processing has been completed to the recording unit 111.

  The recording unit 111 converts an image signal and an audio signal into a data format suitable for recording, and writes data to and reads stored data from a recording medium such as a data tape, an optical disk, or a flash memory.

  FIG. 2 is a diagram illustrating a configuration example of the audio processing unit 110. The audio processing unit 110 performs digital signal processing. The audio processing unit 110 includes bit shifters 201, 202, 208, 209, 213, 214, 220, before and after a plurality of signal addition / subtraction units, filter processing units, and absolute value conversion processing units to prevent overflow due to signal processing. 235, 236, 242. The shift amounts of these bit shifters are set so that an appropriate signal level can be obtained for each arrangement location. Further, the bit shifter may be arranged at other positions as required.

  The audio processing unit 110 receives the right channel audio signal Rch and the left channel audio signal Lch from the sound collection unit 109. The bit shifter 201 bit-shifts and outputs the right channel audio signal Rch. The bit shifter 202 bit-shifts the left channel audio signal Lch and outputs it. The adder 203 adds the output signals of the bit shifters 201 and 202 to output in-phase components (in-phase components) included in the right channel audio signal Rch and the left channel audio signal Lch. The adder 203 is an in-phase component generation unit that generates in-phase components of the plurality of audio signals Rch and Lch. The subtracter 204 subtracts the output signal of the bit shifter 202 from the output signal of the bit shifter 201, thereby outputting a signal of an antiphase component (an antiphase component) included in the right channel audio signal Rch and the left channel audio signal Lch. . The subtractor 204 is an anti-phase component generation unit that generates anti-phase components of the plurality of audio signals Rch and Lch. This in-phase component signal contains a large amount of normal speech, and the low-frequency component of the anti-phase component contains a lot of wind noise. Wind noise is noise generated by the wind blown near the sound collection unit 109.

  The wind noise processing means includes a high-pass filter (hereinafter referred to as HPF) 205, an adder 206, and a subtractor 207, and performs wind noise reduction processing on a plurality of audio signals Rch and Lch. The HPF 205 is high-pass filter means, and reduces wind noise by attenuating the low-frequency band of the anti-phase component output from the subtractor 204. The CPU 102 controls the on / off and cut-off frequency of the HPF 205 according to a wind noise detection result to be described later. That is, when the wind noise reduction process is not performed, the CPU 102 controls the HPF 205 so that the low frequency band of the input signal is output without being attenuated. When performing wind noise reduction processing, the CPU 102 controls the HPF 205 to attenuate and output the low frequency band of the input signal. Further, when the wind noise reduction process is performed, the CPU 102 controls to change the cutoff frequency of the HPF 205 to a higher frequency side as the detected wind noise is larger. The adder 206 is a first addition means, and adds the in-phase component output from the adder 203 and the anti-phase component output from the HPF 205 to add the right channel audio signal after the wind noise reduction processing is performed. Is output. The subtractor 207 is a first subtracting means, and subtracts the anti-phase component output from the HPF 205 from the in-phase component output from the adder 203 to thereby perform the left channel audio signal after being subjected to the wind noise reduction process. Is output. Although the effect of wind noise reduction by the HPF 205 appears, an HPF may be added after the adder 206 and the subtractor 207 in order to correct the audibility of the low frequency range that includes more wind noise.

  The bit shifter 208 bit-shifts the output signal of the adder 206 and outputs it. The bit shifter 209 bit shifts the output signal of the subtracter 207 and outputs it. The other processing unit 210 performs signal processing such as frequency characteristic correction and ALC (automatic level control) on the audio signal that has been subjected to the wind noise reduction processing output from the bit shifters 208 and 209, and the right channel audio signal Rch and A left channel audio signal Lch is generated. Then, the other processing unit 210 transmits the right channel audio signal Rch and the left channel audio signal Lch to the recording unit 111 via the internal bus 101.

  Next, the configuration of the wind noise detection unit in the sound processing unit 110 will be described. A low-pass filter (hereinafter referred to as LPF) 211 passes only a signal in a low frequency band (first frequency band) out of in-phase component signals output from the adder 203. The LPF 211 is a first extraction unit that extracts a signal in the first frequency band from the signals having the in-phase components. The LPF 211 may be a band-pass filter (hereinafter referred to as BPF) that allows a desired frequency band to pass. The bit shifter 213 bit-shifts the output signal of the LPF 211 and outputs it. The absolute value circuit (ABS) 215 is a first absolute value means, which converts a positive / negative amplitude signal output from the bit shifter 213 into an absolute value signal and outputs it.

  The LPF 212 passes only the signal in the low frequency band (first frequency band) out of the antiphase component signals output from the subtractor 204. The LPF 212 is a second extracting unit that extracts a signal in the second frequency band from the signals of the above antiphase components. The LPF 212 may be a BPF that passes a desired frequency band. The bit shifter 214 bit-shifts the output signal of the LPF 212 and outputs it. The absolute value circuit 216 is a second absolute value means, which converts a positive / negative amplitude signal output from the bit shifter 214 into an absolute value signal and outputs it.

  The amplifier 217 amplifies the output signal of the absolute value circuit 216 and outputs it. The subtractor 218 subtracts the in-phase component output from the amplifier 217 from the anti-phase component output from the absolute value circuit 216, thereby outputting the level difference between the two in the low frequency band. The subtractor 218 is a first difference unit that outputs a difference between the output signal of the absolute value circuit 216 and the output signal of the amplifier 217. As described above, since the wind noise includes many anti-phase components in the low frequency band, the magnitude of the wind noise can be estimated from the subtraction result of the subtractor 218. At this time, it is possible to set by the amplifier 217 how much level difference occurs between both the integrators 221 and 222 to be described later.

  Here, the information desired to be obtained by the subtractor 218 is how large the anti-phase component is relative to the in-phase component. Information that makes the negative phase component smaller is unnecessary, and if integrators 221 and 222, which will be described later, have integrated the values in the negative direction, the positive values are integrated immediately after detecting the wind noise. I can't go. For this reason, a negative value limiter 219 is provided.

  The negative value limiting limiter 219 is a first negative value limiting means, and does not output when the value of the output signal of the subtractor 218 is negative, but outputs it when it is 0 or positive. Thereby, the integrators 221 and 222 integrate the output of the subtractor 218 only when the anti-phase component is larger than the in-phase component. The bit shifter 220 bit-shifts the output signal of the negative value limiter 219 and outputs it. The integrator 221 is first integrating means for integrating the output signal of the bit shifter 220. The integrator 222 is a third integration unit that integrates the output signal of the bit shifter 220. The integrator 221 and the integrator 222 have different integration periods, and the integration period of the integrator 222 is longer than the integration period of the integrator 221. Therefore, the integrator 221 quickly integrates the value when the anti-phase component in the low frequency band is larger than the in-phase component, and transmits it to the CPU 102 as the short-term integrated value short_low in the low frequency band. On the other hand, the integrator 222 integrates the value relatively gently when the anti-phase component in the low frequency band is larger than the in-phase component, and transmits it to the CPU 102 as the long-term integrated value long_low in the low frequency band.

  Further, the in-phase component signal and the anti-phase component signal obtained by the adder 203 and the subtracter 204 are also used for performing similar detection in a frequency band higher than the first frequency band (second frequency band). Is done. The serial connection of the LPF 231 and the HPF 233 allows only a signal in the middle frequency band (second frequency band) of the in-phase component signals output from the adder 203 to pass. The LPF 231 and the HPF 233 are third extraction means for extracting a signal in the second frequency band from the above in-phase component signals. Note that the LPF 231 and the HPF 233 may be connected in series by one BPF. The bit shifter 235 bit shifts the output signal of the HPF 233 and outputs it. The absolute value circuit 237 is a third absolute value means, which converts the positive / negative amplitude signal output from the bit shifter 235 into an absolute value signal and outputs it.

  The serial connection of the LPF 232 and the HPF 234 allows only the signal in the middle frequency band (second frequency band) of the signals of the reverse phase components output from the subtractor 204 to pass. The LPF 232 and the HPF 234 are fourth extraction means for extracting a signal in the second frequency band from the above-described antiphase component signals. The series connection of the LPF 232 and the HPF 234 may be one BPF. The bit shifter 236 bit-shifts the output signal of the HPF 234 and outputs it. The absolute value circuit 238 is a fourth absolute value means, which converts the positive / negative amplitude signal output from the bit shifter 236 into an absolute value signal and outputs it.

  The amplifier 239 amplifies the output signal of the absolute value circuit 237 and outputs it. The subtracter 240 subtracts the in-phase component output from the amplifier 239 from the anti-phase component output from the absolute value circuit 238, thereby outputting the level difference between the two in the mid-frequency range. The subtractor 240 is a second difference unit that outputs a difference between the output signal of the absolute value circuit 238 and the output signal of the amplifier 239. The negative value limiting limiter 241 is a second negative value limiting means, and does not output when the value of the output signal of the subtractor 240 is negative, but outputs it when it is 0 or positive. The bit shifter 242 bit-shifts the output signal of the negative value limiter 241 and outputs it. The integrator 243 is a second integration unit that integrates the output signal of the bit shifter 242. The integration period of the integrator 243 is the same as the integration period of the integrator 221. When the reverse-phase component in the middle range is larger than the in-phase component, the integrator 243 quickly integrates the value and transmits it to the CPU 102 as the short-term integral value short_mid in the middle range.

  Next, the difference between the wind noise and the touch sound of the sound processing unit 110 and the wind noise reduction process based on the difference will be described. FIG. 3 is an example of a spectrum diagram showing the frequency distribution of the touch sound at the outputs of the adder 203 and the subtracter 204. The in-phase component of the touch sound is an output signal of the adder 203. The antiphase component of the touch sound is an output signal of the subtracter 204. It can be seen that in the low frequency band, an anti-phase component comparable to the in-phase component is generated. Similarly, a reverse phase component comparable to the in-phase component appears in the middle frequency band.

  FIG. 4 is an example of a spectrum diagram showing the frequency distribution of wind noise at the outputs of the adder 203 and the subtracter 204. The in-phase component of wind noise is the output signal of the adder 203. The anti-phase component of wind noise is the output signal of the subtractor 204. Similar to the touch sound, it can be seen that the wind noise has an anti-phase component comparable to the in-phase component in the low frequency band. This is the reason why it is difficult to distinguish the difference between wind noise and touch sound only by the magnitude of the antiphase component in the low sound range. However, when wind noise occurs, the frequency range of the middle sound range has different characteristics from the touch sound. In the wind noise, it can be seen that the anti-phase component is clearly smaller than the in-phase component in the frequency band extending from 300 Hz to 4000 Hz. Therefore, the first frequency band includes a part or all of less than 300 Hz, and the second frequency band includes a part or all of 300 Hz or more and 4000 Hz or less.

  When wind noise occurs, a negative-phase component comparable to the in-phase component appears in the low frequency band, but during the actual wind noise generation, the negative-phase component is larger than the in-phase component. The state of large is randomly generated with the passage of time. The difference value output from the negative value limiter 219 is integrated by the integrator 221 at the timing when the negative phase component is larger. As a result, when wind noise is included, the integral value of the integrator 221 increases, and it can be seen that wind noise is generated by detecting the integral value of the integrator 221. On the other hand, when a touch sound is generated, an anti-phase component comparable to the in-phase component appears in the low frequency band, so that the integral value of the integrator 221 becomes large as in the case of wind noise.

  However, if wind noise is included, the output to the integrator 243 is limited by the negative value limiter 241 because the anti-phase component is smaller than the in-phase component in the midrange, and the integrator 243 The integral value does not increase. On the other hand, when a touch sound is included, a negative phase component comparable to the in-phase component appears even in the middle range as shown in FIG. 3, so that the negative value limiter 241 outputs the negative phase component at a larger timing. The resulting difference value is integrated.

  Therefore, even when the integration value of the integrator 221 is large, whether the wind noise is generated by checking the integration value of the integrator 243 or a touch sound is included instead of the wind noise. It can be detected. That is, even if the integration value of the integrator 221 is large, it can be determined that the noise is wind noise if the integration value of the integrator 243 is not large.

  FIG. 5 shows integrated values short_low, short_mid, and long_low transmitted from each integrator to the CPU 102 when the input audio signal includes wind noise wind and touch sound touch.

  First, a case where the audio signal includes only the touch sound touch will be described. In the period T1 during which the touch sound touch is acquired, the anti-phase components increase in both the low frequency band and the middle frequency band as seen in the spectrum diagram of FIG. At this time, the integrator 221 quickly integrates the integral value short_low, and the integral value short_low becomes equal to or greater than the threshold value TH2. Further, the integrator 243 also integrates the integral value short_mid rapidly, and the integral value short_mid reaches a certain value.

  When the integral value short_low becomes equal to or greater than the predetermined value TH2, the CPU 102 compares the integral value short_low with the integral value short_mid. At this time, since the integral value short_mid is close to the integral value short_low, the difference between the two values does not increase and does not exceed the threshold value TH3. Since it can be determined from this result that the input noise is a touch sound, the CPU 102 performs control so as not to perform the wind noise reduction process.

  Next, a case where the audio signal includes only wind noise wind will be described. In the periods T2 and T3 during which the wind noise wind is acquired, the anti-phase component increases in the low frequency band as seen in the spectrum diagram of FIG. Therefore, in the period T2 having the same length as the period T1, the integrator 221 quickly integrates the integral value short_low, and the integral value short_low exceeds the threshold value TH2, but the integral value short_mid of the integrator 243 does not increase.

  When the integral value short_low becomes equal to or greater than the threshold value TH2, the CPU 102 compares the integral value short_low with the integral value short_mid. The integral value short_low is a large value, but the integral value short_mid is a small value, so that the difference between the two values is large and is equal to or greater than the threshold value TH3. From this result, since it can be determined that the input noise is wind noise, the CPU 102 performs control to perform wind noise reduction processing. At this time, the CPU 102 may change the setting of the cutoff frequency of the HPF 205 according to the integration amount and integration speed of the integration value short_low.

  Also, after the start of the wind noise reduction process, if the state of many low-phase components in the low frequency band continues, the integration value long_low that the integrator 222 gently integrated becomes equal to or greater than the threshold value TH1. In the period T3, the CPU 102 shifts the judgment criterion for the control of the wind noise reduction process to that based on the integral value long_low. That is, the CPU 102 performs control so as to perform wind noise reduction processing when the integral value long_low is equal to or greater than the threshold value TH1. Thereby, it is possible to prevent a sensitive reaction that may be caused by a short integration time of the integrated values short_low and short_mid.

  Next, a case where the audio signal includes wind noise wind and touch sound touch will be described. In the period T2, the CPU 102 determines that the noise is wind noise, and performs wind noise reduction processing. In the period T4 during which the wind noise reduction process is in operation, the integral value short_mid becomes large, and the difference between the integral values short_low and short_mid becomes smaller than the threshold value TH3. In that case, the noise acquired in the period T4 is considered to be a touch sound. However, at this time, since the integration value long_low that has already been gently integrated by the integrator 222 is equal to or greater than the predetermined value TH1, the judgment criterion for the control of wind noise reduction processing is based on the value of the integration value long_low. It has migrated. Accordingly, the wind noise reduction processing is continuously performed without being affected by the state of the integral value short_mid.

  FIG. 6 is a flowchart illustrating the audio signal processing method of the imaging apparatus 100, and illustrates a wind noise reduction processing method. The processing in FIG. 6 is performed by the CPU 102 controlling each unit. First, in step S11, the CPU 102 determines whether or not the long-term integration value long_low in the low frequency band is greater than or equal to a threshold value (greater than or equal to a third threshold value TH1). If the integrated value long_low is greater than or equal to the threshold value TH1, the CPU 102 determines that wind noise is included in the audio signal, proceeds to step S14, and the integrated value long_low is less than the threshold value (less than the threshold value TH1). In that case, the process proceeds to step S12. In step S12, the CPU 102 determines whether or not the short period integral value short_low in the low frequency band is equal to or greater than the first threshold value TH2, and if it is equal to or greater than the threshold value TH2, the process proceeds to step S13 and is less than the threshold value TH2. If so, the process proceeds to step S15.

  In step S13, the CPU 102 compares the short-term integrated value short_mid in the middle frequency band and the short-term integrated value short_low in the low frequency band to determine whether the sound signal includes wind noise. If the value obtained by subtracting the integral value short_mid from the integral value short_low is equal to or greater than the threshold value TH3, the CPU 102 determines that wind noise is included in the audio signal, and proceeds to step S14. On the other hand, if the value obtained by subtracting the integral value short_mid from the integral value short_low is less than the threshold value TH3, the CPU 102 determines that the sound signal does not include wind noise, and advances the process to step S15. That is, in step S13, if the difference between the integral value short_low and the integral value short_mid is greater than or equal to the second threshold value TH3, the CPU 102 advances the process to step S14.

  On the other hand, when the difference between the integral value short_low and the integral value short_mid is less than the second threshold value TH3, the CPU 102 advances the process to step S15. In step S14, the CPU (control means) 102 determines that the sound signal includes wind noise, and causes the sound processing unit 110 to perform wind noise reduction processing on the plurality of sound signals Rch and Lch. Control.

  The other processing unit 210 in the sound processing unit 110 transmits the right channel sound signal Rch and the left channel sound signal Lch subjected to the wind noise reduction process to the CPU 102, and the CPU 102 returns the process to step S11. In step S15, the CPU 102 controls the plurality of audio signals Rch and Lch not to perform the wind noise reduction process, and returns the process to step S11. For example, the CPU 102 controls the HPF 205 so as not to perform the wind noise reduction process by controlling the HPF 205 to the operation stop state (off state). In that case, the HPF 205 passes the input signal as it is.

  As described above, in this embodiment, the audio processing unit 110 detects the frequency component in the middle sound range in addition to the low frequency component of the difference between the in-phase component and the anti-phase component of the right channel audio signal Rch and the left channel audio signal Lch. . If the difference between the in-phase component and the low-frequency component is larger than the threshold value TH2, the CPU 102 proceeds to step S13. In step S13, if the difference between the difference between the low-frequency component of the in-phase component and the anti-phase component and the difference between the frequency component of the mid-frequency component of the in-phase component and the anti-phase component is smaller than the threshold value TH3, the CPU 102 It is determined that it is not included, and the wind noise reduction process is not performed.

  Thus, the present embodiment can surely reduce wind noise, and does not include wind noise and does not perform wind noise reduction processing when touch sound is included. It is possible to prevent the sound quality from being deteriorated by the reduction process.

  Here, in the configuration of FIG. 2, an integrator 222 having a long integration period is provided, and the CPU 102 detects wind noise based on the output value long_low of the integrator 222. A case where noise reduction processing is performed will be described. If the integrator 222 is eliminated in the process of FIG. 6, if a touch sound is generated during the execution of the wind noise reduction process, the wind noise reduction process is interrupted. Therefore, the process shown in FIG. 7 is performed.

  FIG. 7 is a flowchart illustrating a sound signal processing method of the imaging apparatus 100, and illustrates a wind noise reduction processing method. First, in step S21, the CPU 102 determines whether or not the short-term integrated value short_low in the low frequency band is greater than or equal to the threshold value TH2. If the integrated value short_low is equal to or greater than the threshold value TH2, the CPU 102 advances the process to step S22 in order to determine whether or not wind noise is included in the voice. On the other hand, when the integral value short_low is less than the threshold value TH2, the CPU 102 advances the process to step S25.

  In step S22, the CPU 102 compares the short-term integral value short_mid in the mid-frequency band with the short-term integral value short_low in the low-frequency band. If the value obtained by subtracting the integral value short_mid from the integral value short_low is equal to or greater than the threshold value TH3, the CPU 102 determines that wind noise is included in the audio signal, and proceeds to step S24. On the other hand, when the value obtained by subtracting the integral value short_mid from the integral value short_low is less than the threshold value TH3, the CPU 102 advances the process to step S23. That is, in step S22, if the difference between the integral value short_low and the integral value short_mid is greater than or equal to the threshold value TH3, the CPU 102 advances the process to step S24. If the difference between the integral value short_low and the integral value short_mid is less than the threshold value TH3, the CPU 102 advances the process to step S23.

  In step S23, the CPU 102 determines whether or not a wind noise reduction process has been performed in the previous process. When the CPU 102 performs wind noise reduction processing in the previous processing, the CPU 102 is performing wind noise reduction processing on the plurality of audio signals Rch and Lch, and the audio signal includes wind noise. Judge and proceed to step S24. In this case, in step S24, the CPU 102 is performing a wind noise reduction process on the plurality of audio signals Rch and Lch, and performs a sound so as to continue the wind noise reduction process on the plurality of audio signals Rch and Lch. The processing unit 110 is controlled.

  In step S23, if the CPU 102 has not performed the wind noise reduction process in the previous process, the CPU 102 determines that the wind noise is not included in the audio signal, and advances the process to step S25. In step S24, the CPU 102 determines that the sound signal includes wind noise, and controls the sound processing unit 110 to perform wind noise reduction processing on the plurality of sound signals Rch and Lch. The other processing unit 210 in the sound processing unit 110 transmits the right channel sound signal Rch and the left channel sound signal Lch subjected to the wind noise reduction process to the CPU 102, and the CPU 102 returns the process to step S21. In step S25, the CPU 102 controls the plurality of audio signals Rch and Lch not to perform the wind noise reduction process, and returns the process to step S21.

  As described above, step S21 is the same process as step S12 of FIG. Step S22 is the same process as step S13 of FIG. In step S13, when the value obtained by subtracting the integral value short_mid from the integral value short_low is less than the threshold value TH3, the CPU 102 does not operate the wind noise reduction process.

  On the other hand, in step S23, the CPU 102 determines whether or not wind noise reduction processing has been performed in the previous processing. If the CPU 102 performs the wind noise reduction process in the previous process, the CPU 102 continues the wind noise reduction process without interruption even if the touch sound is collected during the wind noise reduction process. be able to.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

203 Adder, 204 Subtractor, 211, 212, 231, 232 LPF, 233, 234 HPF, 218, 240 Subtractor, 221, 222, 243 Integrator

Claims (11)

In-phase component generating means for generating in-phase components of a plurality of audio signals;
Anti-phase component generating means for generating anti-phase components of the plurality of audio signals;
First extraction means for extracting a signal in a first frequency band from the signals of the in-phase component;
Second extraction means for extracting a signal of the first frequency band out of the signal of the negative phase component;
Third extraction means for extracting a signal in a second frequency band higher than the first frequency band in the in-phase component signal;
A fourth extraction means for extracting a signal of the second frequency band from the signal of the negative phase component;
First difference means for outputting a difference between the signal extracted by the first extraction means and the signal extracted by the second extraction means;
Second difference means for outputting a difference between the signal extracted by the third extraction means and the signal extracted by the fourth extraction means;
First integration means for integrating the difference output by the first difference means;
Second integration means for integrating the difference output by the second difference means;
The integration value of the first integration means is greater than or equal to a first threshold, and the difference between the integration value of the first integration means and the integration value of the second integration means is greater than or equal to a second threshold. And a control means for performing control so as to perform wind noise reduction processing on the plurality of audio signals. And a third integration means for integrating the difference output from the first difference means in an integration period longer than the integration period of the first integration means,
The control means performs control so that wind noise reduction processing is performed on the plurality of audio signals when an integration value of the third integration means is equal to or greater than a third threshold value. Item 2. The audio signal processing device according to Item 1.   When the integral value of the third integrator is equal to or greater than a third threshold, the control means determines whether the integral value of the first integrator is equal to or greater than a first threshold; and Control is performed so that wind noise reduction processing is performed on the plurality of audio signals regardless of whether the difference between the integration value of the integration means and the integration value of the second integration means is greater than or equal to a second threshold value. The audio signal processing apparatus according to claim 2, wherein:   The control means has an integration value of the first integration means equal to or greater than a first threshold, and a difference between the integration value of the first integration means and the integration value of the second integration means is a second value. Even if it is less than the threshold, when the wind noise reduction process is being performed on the plurality of audio signals, control is performed to continue the wind noise reduction process on the plurality of audio signals. The audio signal processing apparatus according to claim 1.   5. The audio signal processing apparatus according to claim 1, wherein the first frequency band includes a part or all of less than 300 Hz.   6. The audio signal processing device according to claim 1, wherein the second frequency band includes a part or all of 300 Hz to 4000 Hz.   The audio signal processing apparatus according to any one of claims 1 to 6, wherein the plurality of audio signals are a right channel audio signal and a left channel audio signal. Furthermore, it has wind noise processing means for performing wind noise reduction processing on the plurality of audio signals,
The wind noise processing means is
High pass filter means for attenuating the low frequency band of the anti-phase component;
First addition means for adding the in-phase component and the output signal of the high-pass filter means;
8. The audio signal processing apparatus according to claim 1, further comprising a first subtracting unit that subtracts an output signal of the high-pass filter unit from the in-phase component. A first absolute value means for converting the signal extracted by the first extraction means into an absolute value signal;
Second absolute value means for converting the signal extracted by the second extraction means into an absolute value signal;
Third absolute value means for converting the signal extracted by the third extraction means into an absolute value signal;
Fourth absolute value means for converting the signal extracted by the fourth extraction means into an absolute value signal;
When the value of the output signal of the first difference means is negative, the value of the output signal of the first difference means is not output, and the first negative value limiting means that outputs when the value is 0 or positive When,
When the value of the output signal of the second difference means is negative, the value of the output signal of the second difference means is not output, and the second negative value limiting means that outputs when the value is 0 or positive And
The first difference means outputs a value obtained by subtracting the output signal of the first absolute value means from the output signal of the second absolute value means,
The second difference means outputs a value obtained by subtracting the output signal of the third absolute value means from the output signal of the fourth absolute value means,
The first integrating means integrates the output signal of the first negative value limiting means,
9. The audio signal processing apparatus according to claim 1, wherein the second integration unit integrates an output signal of the second negative value limiting unit. An in-phase component generation step of generating in-phase components of a plurality of audio signals by the in-phase component generation means;
A negative phase component generating step of generating negative phase components of the plurality of audio signals by a negative phase component generating means;
A first extraction step of extracting a signal in a first frequency band from the in-phase component signal by a first extraction means;
A second extraction step of extracting a signal of the first frequency band out of the signal of the negative phase component by a second extraction means;
A third extraction step of extracting a signal of a second frequency band higher than the first frequency band of the signals of the in-phase component by a third extraction unit;
A fourth extraction step of extracting a signal of the second frequency band out of the signal of the negative phase component by a fourth extraction means;
A first difference step for outputting a difference between the signal extracted in the first extraction step and the signal extracted in the second extraction step by a first difference means;
A second difference step for outputting a difference between the signal extracted in the third extraction step and the signal extracted in the fourth extraction step by a second difference means;
A first integration step of integrating the difference output in the first difference step by a first integration means;
A second integration step of integrating the difference output in the second difference step by a second integration means;
The control means has an integration value of the first integration step equal to or greater than a first threshold value, and a difference between the integration value of the first integration step and the integration value of the second integration step is a second threshold value. And a control step for performing control so as to perform wind noise reduction processing on the plurality of audio signals.   The program for functioning a computer as each means of the audio | voice signal processing apparatus as described in any one of Claim 1 to 9.

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