JP5897489B2 - Audio signal processing apparatus, audio signal processing method, and audio signal processing program - Google Patents

Description

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

In Patent Document 1, a DSP that processes a digital signal obtained by amplifying an audio signal input from a microphone and then digitally converting the signal has an AGC circuit. In this apparatus, when the input level on the receiving side is low and the calculation accuracy of the pseudo echo signal is insufficient, the AGC circuit reduces the output of the digital signal to prevent howling.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-125071

  However, the above-described apparatus has a problem that it is difficult to improve the S / N ratio because the ratio of noise to the sound subjected to digital conversion processing increases when the input sound is small.

In the first aspect of the present invention, an audio input unit that outputs an input analog audio signal corresponding to an input audio, and a conversion unit that digitally converts the input analog audio signal within a dynamic range and outputs it as an input digital audio signal And a control unit for controlling the conversion unit, the conversion unit amplifying or attenuating the input analog audio signal, and A / A for digitally converting the amplified or attenuated input analog audio signal D conversion unit, the control unit, based on either the input digital audio signal and the pseudo echo signal calculated from the external audio signal input from the outside, the analog gain of the analog amplifier unit the audio signal processing device for setting, as well, to provide an audio signal processing method and audio signal processing program.

In the second aspect of the present invention, an audio input unit that outputs an input analog audio signal corresponding to the input audio, and a conversion unit that digitally converts the input analog audio signal within a dynamic range and outputs the converted signal as an input digital audio signal. And a control unit for controlling the conversion unit, the conversion unit amplifying or attenuating the input analog audio signal, and A / A for digitally converting the amplified or attenuated input analog audio signal A D conversion unit, the control unit controls an analog gain of the analog amplifier unit to adapt to an intensity of the input analog audio signal, and the analog amplifier unit has an intensity of the input analog audio signal , An audio signal processing device that changes the analog gain at the timing of zero crossing, an audio signal processing method, and audio To provide a No. processing program.

In the third aspect of the present invention, an audio input unit that outputs an input analog audio signal corresponding to the input audio, and a conversion unit that digitally converts the input analog audio signal within a dynamic range and outputs it as an input digital audio signal And a control unit for controlling the conversion unit, and a digital amplifier unit for amplifying or attenuating the input digital audio signal, the conversion unit amplifying or attenuating the input analog audio signal, and an amplification Or an A / D converter that digitally converts the attenuated input analog audio signal, and the control unit controls the analog gain of the analog amplifier unit to adapt to the intensity of the input analog audio signal. The digital gain of the digital amplifier unit according to the analog gain set in the analog amplifier unit The control unit obtains a change timing at which the analog gain of the analog amplifier unit is changed from the analog amplifier unit, and changes the digital gain of the digital amplifier unit based on the change timing. An audio signal processing device that controls timing, an audio signal processing method, and an audio signal processing program are provided.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 is an overall configuration diagram of an audio signal processing device 10. FIG. 2 is an overall configuration diagram of a control unit 30. FIG. It is a figure explaining peak detection and peak output. It is a block diagram explaining AGC52. It is a figure explaining the setting of the target gain (mu) by the target gain setting part. 4 is a block diagram illustrating a timing control unit 28. FIG. It is a figure explaining the case where variable analog gain alpha1 is changed at timings other than a zero cross for comparison. It is a figure explaining the case where variable analog gain alpha1 is changed at the timing of zero crossing. It is a figure explaining the time change of a signal. 4 is a flowchart of audio signal processing by the audio signal processing device 10. 2 shows an exemplary hardware configuration of a computer 1900 according to the present embodiment.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is an overall configuration diagram of the audio signal processing apparatus 10. As an example, the audio signal processing apparatus 10 is a hands-free communication device in which an audio input unit and an audio output unit are integrated, a conference system having an audio input unit and an audio output unit, a house or a building (for example, a kitchen and the like). It is installed in intercoms that enable conversation in a bath, etc., and intercoms that connect indoors and outdoors. The audio signal processing device 10 controls the conversion unit 22 so that the input analog audio signal SS21 falls within the dynamic range of the conversion unit 22. Thereby, the audio signal processing apparatus 10 digitally converts the input analog audio signal SS21 with a dynamic range adapted to the intensity of the input analog audio signal SS21. Thereby, the audio signal processing apparatus 10 improves the accuracy of A / D conversion and the S / N ratio.

  As shown in FIG. 1, the audio signal processing device 10 includes an input / output unit 12.

  The input / output unit 12 wirelessly communicates with an external device such as a portable device or a computer at the far end, or transmits / receives information including an audio signal to / from other devices including other audio signal processing devices. For example, the far-end input digital audio signal SS10 is input to the input / output unit 12 from an external device. The far-end input digital audio signal SS10 is an example of an external audio signal. The input / output unit 12 is connected to the D / A conversion unit 14. The input / output unit 12 outputs the far-end input digital audio signal SS10 to the D / A conversion unit 14. When the audio signal input from the far end is an analog signal, the input / output unit 12 may digitally convert the audio signal into the far end input digital audio signal SS10 and output the digital signal. In addition, the input / output unit 12 outputs a far-end output audio signal SS20 input from an echo canceller unit 26 described later to an external device by wireless communication or the like. The input / output unit 12 may output a far-end output audio signal obtained by converting the far-end output audio signal SS20 into an analog signal as necessary.

  The audio signal processing apparatus 10 includes a DSP (Digital signal processor) 70 that performs digital processing of far-end side audio input and output, and a CODEC (COder / DECoder) that performs analog processing related to near-end side audio output and input. 72. At least some of the echo canceller unit 26, the control unit 30, and the digital amplifier unit 24 may be configured by the DSP 70. Further, at least a part of the D / A conversion unit 14, the output amplifier 16, and the conversion unit 22 may be configured by the CODEC 72. Hereinafter, the configuration of the DSP 70 and the CODEC 72 is divided into a far-end input side and a near-end output side that are the receiving side, and a near-end input side and a far-end output side that are the transmitting side. explain.

  The audio signal processing device 10 further includes a D / A conversion unit 14, an output amplifier 16, and an audio output unit 18.

  The D / A converter 14 receives the far-end input digital audio signal SS10 from the input / output unit 12. Here, the D / A converter 14 may be configured such that the far-end input digital audio signal SS10 input from the input / output unit 12 is input via the DSP 70. The D / A converter 14 analog-converts the far-end input digital audio signal SS10 into a far-end input analog audio signal SS11. The analog output terminal of the D / A converter 14 is directly or indirectly connected to the output amplifier 16. The D / A converter 14 outputs the far-end input analog audio signal SS11 to the output amplifier 16.

  The output amplifier 16 amplifies the far-end input analog audio signal SS11 input from the D / A converter 14 with a gain ε. The gain in this embodiment is the ratio of output to input. Therefore, the relationship between the input SSin, the output SSout, and the gain Ga satisfies SSout = Ga × SSin. The output amplifier 16 is directly or indirectly connected to the audio output unit 18. The output amplifier 16 outputs the amplified far-end input analog audio signal SS12 to the audio output unit 18.

  For example, the audio output unit 18 is a speaker including headphones and earphones. The audio output unit 18 converts the electrical far-end input analog audio signal SS12 input from the output amplifier 16 into a far-end output audio FS1, which is an example of output audio, and outputs it.

  The audio signal processing device 10 further includes an audio input unit 20, a conversion unit 22, a digital amplifier unit 24, an echo canceller unit 26, a timing control unit 28, and a control unit 30.

  The voice input unit 20 is, for example, a microphone such as a condenser microphone. Near-end input speech NS such as a user wearing the speech signal processing device 10 or a user in the vicinity of the speech signal processing device 10 is input to the speech input unit 20. In addition, the far-end output voice FS1 output from the voice output unit 18 is transmitted to the voice input unit 20 through the housing or the like, and the far-end input voice FS2 including reflection of the indoor wall or the like is input as an echo. Here, the far-end input voice FS2 is the product of the echo gain γ1 and the far-end output voice FS1 due to the structure of the casing of the voice signal processing apparatus 10 or the like. The voice input unit 20 analog-converts the near-end input voice NS and the far-end input voice FS2 into an input analog voice signal SS21 that is an electrical analog signal. The voice input unit 20 is directly or indirectly connected to the conversion unit 22. The audio input unit 20 outputs the input analog audio signal SS21 to the conversion unit 22.

  The conversion unit 22 is connected between the audio input unit 20 and the digital amplifier unit 24. The conversion unit 22 amplifies the input analog audio signal SS21 input from the audio input unit 20 and digitally converts it to output it to the digital amplifier unit 24 as an input digital audio signal SS23. The conversion unit 22 further includes an analog amplifier unit 32 and an A / D conversion unit 34.

  The analog amplifier unit 32 amplifies the input analog audio signal SS21 input from the audio input unit 20 with a variable analog gain α1. The variable analog gain α1 of the analog amplifier unit 32 is controlled by the control unit 30 connected via the timing control unit 28. Here, “α1 = α0 + Δα” is preferable. Α0 is an initial value of the variable analog gain α1, and Δα is a difference from the initial value α0. The analog amplifier unit 32 is directly or indirectly connected to the A / D conversion unit 34. The analog amplifier unit 32 outputs the amplified input analog audio signal SS22 to the A / D conversion unit 34.

  The analog amplifier unit 32 is directly or indirectly connected to the timing control unit 28. The analog amplifier unit 32 detects a zero cross, which is a timing at which the intensity of the input analog audio signal SS22 becomes “0”, and outputs a detection signal DS to the timing control unit 28.

  The A / D converter 34 has a dynamic range indicating a range in which an analog signal can be digitally converted. The A / D conversion unit 34 digitally converts the input analog audio signal SS22 amplified by the analog amplifier unit 32 into an input digital audio signal SS23 within a dynamic range. The A / D conversion unit 34 is directly or indirectly connected to the digital amplifier unit 24 and the control unit 30. The conversion unit 22 outputs the input digital audio signal SS23 to the digital amplifier unit 24 and the control unit 30.

  The digital amplifier unit 24 amplifies or attenuates the input digital audio signal SS23 input from the A / D conversion unit 34 of the conversion unit 22 with the variable digital gain β1. For example, the digital amplifier unit 24 attenuates the input digital audio signal SS23 with the variable digital gain β1 set to the reciprocal of the variable analog gain α1. In other words, the digital amplifier unit 24 attenuates the output of the input digital audio signal SS23 to substantially the same intensity as before being amplified by the analog amplifier unit 32. The digital amplifier unit 24 is directly or indirectly connected to the echo canceller unit 26. The digital amplifier unit 24 outputs the attenuated input digital audio signal SS24 to the echo canceller unit 26.

  The echo canceller unit 26 is directly or indirectly connected to the far end input side and the far end output side of the input / output unit 12. The echo canceller unit 26 cancels a component corresponding to the far-end input digital audio signal SS10 input from the far-end input side of the input / output unit 12 from the input digital audio signal SS23 input from the digital amplifier unit 24. An output audio signal SS20 is generated. The echo canceller unit 26 outputs the far-end output audio signal SS20 to the far-end output side of the input / output unit 12. The echo canceller unit 26 includes an adaptive filter 36 and a subtracter 38.

  The adaptive filter 36 is, for example, an FIR (finite impulse response) filter. The adaptive filter 36 is directly or indirectly connected to the far end input side of the input / output unit 12. The far-end input digital audio signal SS 10 is input from the input / output unit 12 to the adaptive filter 36. The adaptive filter 36 generates a pseudo echo signal SS30 obtained by amplifying or attenuating the far-end input digital audio signal SS10 by using the gain ε of the output amplifier 16 and the echo gain γ2 considering the echo gain γ1 of the far-end input speech FS2. To do. For example, the echo gain γ2 is a product of the echo gain γ1, the gain ε of the output amplifier 16, and the initial value α0 of the variable analog gain α1. That is, “γ2 = γ1 × ε × α0”. The pseudo echo signal SS30 is a signal for canceling the component of the far-end input sound FS2 included in the input digital sound signal SS23. The adaptive filter 36 is directly or indirectly connected to the subtractor 38. The adaptive filter 36 outputs the pseudo echo signal SS30 to the subtracter 38.

  The subtractor 38 is directly or indirectly connected to the digital amplifier unit 24. The subtracter 38 receives the input digital audio signal SS24 attenuated from the digital amplifier unit 24. The subtractor 38 subtracts the pseudo echo signal SS30 from the input digital audio signal SS24, thereby generating a far end output audio signal SS20 in which the component of the far end input audio FS2 is canceled. The subtracter 38 is directly or indirectly connected to the far end output side of the input / output unit 12. The subtractor 38 outputs the far-end output audio signal SS20 to the input / output unit 12.

  The timing control unit 28 controls timing for switching the variable analog gain α1 of the analog amplifier unit 32 of the conversion unit 22. The timing control unit 28 acquires the input analog audio signal SS22. A detection signal DS indicating the timing at which the input analog audio signal SS22 is zero-crossed is input from the analog amplifier unit 32 to the timing control unit 28. The timing control unit 28 changes the analog gain α3 output for controlling the variable analog gain α1 of the analog amplifier unit 32 at the zero-cross timing and outputs it.

  The control unit 30 controls the conversion unit 22, the timing control unit 28, and the digital amplifier unit 24 that are directly or indirectly connected. The control unit 30 controls the variable analog gain α <b> 1 via the timing control unit 28, so that the amplified input analog audio signal SS <b> 22 falls within the dynamic range of the A / D conversion unit 34. Thereby, the control unit 30 stores the input analog audio signal SS21 input to the audio input unit 20 in the dynamic range of the conversion unit 22. The control unit 30 controls the timing of changing the variable digital gain β1 and the variable digital gain β1 of the digital amplifier unit 24 by the new analog gain α3 input from the timing control unit 28.

  FIG. 2 is an overall configuration diagram of the control unit 30. As shown in FIG. 2, the control unit 30 includes a first digital amplifier unit 40, a first peak detection unit 42, a second digital amplifier unit 44, a second peak detection unit 46, a comparator 48, and a selector 50. And an AGC 52 and a digital gain calculator 54.

  The first digital amplifier unit 40 is directly or indirectly connected to the far end input side of the input / output unit 12. The first digital amplifier unit 40 receives the far-end input digital audio signal SS10. The first digital amplifier unit 40 is directly or indirectly connected to the first peak detection unit 42. The first digital amplifier unit 40 outputs a pseudo echo signal SS38 obtained by amplifying the far-end input digital audio signal SS10 with an echo gain γ3 to the first peak detection unit 42. Note that “γ3 = ε × γ1”.

  The first peak detector 42 detects the peak of the pseudo echo signal SS38 input from the first digital amplifier 40. The first peak detector 42 is directly or indirectly connected to the comparator 48 and the selector 50. The first peak detector 42 outputs the first peak signal SS41 calculated from the detected peak to the comparator 48 and the selector 50.

  The second digital amplifier unit 44 is directly or indirectly connected to the output side of the A / D conversion unit 34 of the conversion unit 22. The input digital audio signal SS23 output from the A / D conversion unit 34 is input to the second digital amplifier unit 44. The second digital amplifier unit 44 is directly or indirectly connected to the second peak detection unit 46. The second digital amplifier unit 44 outputs the input digital audio signal SS39 obtained by amplifying or attenuating the input digital audio signal SS23 with the variable digital gain α2 to the second peak detection unit 46. Here, the variable digital gain α2 is the reciprocal of the variable analog gain α1 of the analog amplifier unit 32. Accordingly, the second digital amplifier unit 44 outputs the input digital audio signal SS39 having substantially the same intensity as the input analog audio signal SS21 before being amplified by the analog amplifier unit 32.

  The second peak detector 46 detects the peak of the input digital audio signal SS39 input from the second digital amplifier 44. The second peak detector 46 is directly or indirectly connected to the comparator 48 and the selector 50. The second peak detector 46 outputs the second peak signal SS42 calculated from the detected peak to the comparator 48 and the selector 50.

  The comparator 48 compares the first peak signal SS41 and the second peak signal SS42 to determine which is larger. The comparator 48 is directly or indirectly connected to the selector 50. The comparator 48 outputs to the selector 50 determination information JS as to which of the first peak signal SS41 and the second peak signal SS42 is larger.

  The selector 50 is directly or indirectly connected to the AGC 52. The selector 50 outputs a larger signal of the first peak signal SS41 and the second peak signal SS42 to the AGC 52 based on the determination information JS input from the comparator 48.

  AGC 52 is an abbreviation for Automatic Gain Control circuit. The AGC 52 sets the target gain μ based on the first peak signal SS41 and the second peak signal SS42 input from the selector 50. The AGC 52 sets and controls the analog gain α3 that controls the variable analog gain α1 of the analog amplifier unit 32 so as to be the target gain μ. The analog gain α3 is a gain for controlling the variable analog gain α1 of the analog amplifier unit 32. The AGC 52 calculates a gain difference Δ between the current analog gain α3 and the target gain μ. The AGC 52 sets an analog gain α3 at which the gain difference Δ is “0”. The AGC 52 is directly or indirectly connected to the timing control unit 28. The AGC 52 outputs the set analog gain α3 to the analog amplifier unit 32 via the timing control unit 28. Accordingly, the analog amplifier unit 32 changes the current variable analog gain α1 to the newly input analog gain α3.

  The digital gain calculation unit 54 is directly or indirectly connected to the timing control unit 28. The digital gain calculator 54 receives the variable analog gain α1 of the analog amplifier 32 from the timing controller 28. The digital gain calculation unit 54 controls the variable digital gain β1 of the digital amplifier unit 24 by outputting to the digital amplifier unit 24 a digital gain β2 that is the inverse of the variable analog gain α1 input from the timing control unit 28. Thereby, the variable digital gain β1 of the digital amplifier unit 24 becomes a value that cancels the intensity amplified by the variable analog gain α1 of the analog amplifier unit 32.

  The digital gain calculator 54 controls the timing for changing the variable digital gain β1. Specifically, when a zero cross is detected by the analog amplifier unit 32, the analog gain α 3 is input from the timing control unit 28 to the digital gain calculation unit 54. In other words, the analog gain α3 is input from the timing control unit 28 to the digital gain calculation unit 54 at the change timing when the variable analog gain α1 of the analog amplifier unit 32 is changed. As a result, the digital gain calculation unit 54 can control the timing for changing the variable digital gain β1 based on the change timing of the variable analog gain α1. Further, the digital gain calculation unit 54 outputs the digital gain β2 to the digital amplifier unit 24 at a timing shifted from the change timing of the variable analog gain α1 by the time DT2 required for the digital conversion by the A / D conversion unit 34, thereby changing the variable digital gain α1. The gain β1 is changed.

  FIG. 3 is a diagram for explaining peak detection and peak output. The horizontal axis in FIG. 3 indicates time, and the vertical axis indicates the intensity of vibration. The solid line indicates the absolute value of the pseudo echo signal SS38 input to the first peak detector 42. The dotted line indicates the value of the first peak signal SS41 output from the first peak detector 42.

  As illustrated in FIG. 3, when detecting the peak of the pseudo echo signal SS38, the first peak detection unit 42 increases the intensity of the first peak signal SS41 to the peak value, for example, in association with the peak. The first peak detection unit 42 decreases the first peak signal SS41 at the first decrease rate while not detecting the pseudo echo signal SS38 exceeding the first peak signal SS41. The first decrease rate is a predetermined value, and is a value that decreases the intensity of the first peak signal SS41 per unit time. A plurality of first reduction rates may be set in association with the intensity or peak value of the first peak signal SS41. Further, a lower limit may be set for the first peak signal SS41.

  The second peak detector 46 also applies the second reduction rate to the input digital audio signal SS39 and executes the same processing to output the second peak signal SS42. The second decrease rate may be the same value as the first decrease rate or may be a different value.

  FIG. 4 is a block diagram illustrating the AGC 52. As shown in FIG. 4, the AGC 52 includes a target gain setting unit 56 and an attack release setting unit 58.

  The target gain setting unit 56 sets a target gain μ based on target gain information described later. The target gain setting unit 56 outputs the target gain μ to the attack release setting unit 58.

  The attack release setting unit 58 controls the variable analog gain α1 of the analog amplifier unit 32 so that the target gain μ is obtained. Specifically, the output analog gain α3 is input to the attack release setting unit 58 together with the target gain μ. The attack release setting unit 58 calculates a gain difference Δ between the target gain μ and the output analog gain α3. The attack release setting unit 58 changes the analog gain α3 so as to reduce the gain difference Δ and outputs it. In other words, the attack release setting unit 58 sets the analog gain α3 so as to be the target gain μ. Here, the attack release setting unit 58 gradually increases or decreases the analog gain α3 so that the variable analog gain α1 does not change suddenly. The attack release setting unit 58 outputs the analog gain α3 to the analog amplifier unit 32 of the conversion unit 22 via the timing control unit 28. As a result, the analog amplifier unit 32 sets its own variable analog gain α1 so as to be the input analog gain α3, that is, the target gain μ.

  FIG. 5 is a diagram for explaining the setting of the target gain μ by the target gain setting unit 56. The dotted line shown in FIG. 5 shows the relationship between the input and output of the analog amplifier unit 32 with the target gain μ0 for comparison. The target gain μ0 for comparison is such that the input analog audio signal SS22 that is amplified and output by the analog amplifier unit 32 when the input analog audio signal SS21 input to the analog amplifier unit 32 is maximum is output from the A / D conversion unit 34. The maximum dynamic range is set. The solid line shown in FIG. 5 indicates the relationship between the input and output of the analog amplifier unit 32 by the target gain μ, that is, the relationship between the input analog audio signal SS21 and the amplified input analog audio signal SS22. The maximum range on the horizontal axis indicates the maximum value of the input analog audio signal SS21 input to the analog amplifier unit 32. The maximum range on the vertical axis indicates the maximum value of the dynamic range of the A / D converter 34.

  The target gain setting unit 56 sets a target gain μ as indicated by a solid line. Specifically, the target gain setting unit 56 sets the target gain μ to “μ1” when the input analog audio signal SS21 input to the analog amplifier unit 32 is less than the threshold Th. The target gain setting unit 56 sets the target gain μ to “μ2” when the input analog audio signal SS21 input to the analog amplifier unit 32 is equal to or greater than the threshold Th. The relationship between the target gain μ1, the target gain μ2, and the threshold Th is an example of target gain information.

  Here, “μ1> μ0”. Therefore, when the input analog audio signal SS21 input to the analog amplifier section 32 is less than the threshold Th, the dynamic range can be used larger than when the comparison target gain μ0 is used. Note that “μ0> μ2”, but since “μ1> μ0”, when the target gain μ0 for comparison is used in many regions where the input analog audio signal SS21 input to the analog amplifier unit 32 is equal to or greater than the threshold Th. Compared to, you can use a larger dynamic range.

  The target gain μ2 is set so that the input analog audio signal SS22 output from the analog amplifier unit 32 is smaller than the maximum value of the dynamic range when the input analog audio signal SS21 input to the analog amplifier unit 32 has the maximum value. Has been. For example, the target gain μ2 is set so that the input analog audio signal SS22 when the input analog audio signal SS21 has the maximum value is 80% to 90% from the maximum value of the dynamic range. Thereby, it can suppress that the input analog audio | voice signal SS22 which the analog amplifier part 32 outputs exceeds the range of a dynamic range.

  FIG. 6 is a block diagram illustrating the timing control unit 28. As shown in FIG. 6, the timing control unit 28 is a D-FF circuit as an example.

  The timing control unit 28 is provided on the most output side of the attack release setting unit 58 of the AGC 52 and is connected to a D-FF circuit 60 that functions as an output buffer of the DSP 70. The analog gain α3 is input from the AGC 52 to the timing control unit 28. In addition, the detection signal DS is input to the clock input at the timing when the output of the analog amplifier 32 becomes “0”. When the rising edge of the detection signal DS is input, the timing control unit 28 switches the analog gain α3 to be output to the new analog gain α3 input from the AGC 52. As a result, the analog amplifier unit 32 acquires the analog gain α3 at the timing when the output of the input analog audio signal SS21 to be input becomes “0”, and changes the variable analog gain α1 to the newly input analog gain α3. Can be made.

  Next, the reason why the variable analog gain α1 is changed at the zero cross timing will be described. FIG. 7 is a diagram illustrating a case where the variable analog gain α1 is changed at a timing other than zero cross for comparison. FIG. 8 is a diagram illustrating a case where the variable analog gain α1 is changed at the zero cross timing. 7 and 8, the horizontal axis indicates time, and the vertical axis indicates the intensity of the input analog audio signal SS22 output from the analog amplifier unit 32. 7 and 8, the solid line indicates the output of the analog amplifier unit 32 when the variable analog gain α1 is not changed. 7 and 8, the dotted line indicates the output of the analog amplifier unit 32 when the variable analog gain α1 is changed.

  As shown in FIG. 7, when the variable analog gain α1 is changed at a timing other than zero crossing, the output of the analog amplifier section 32 changes abruptly at the timing. Thereafter, even if the digital amplifier unit 24 synchronizes and attenuates the output of the analog amplifier unit 32, a change in sound characteristics may affect the sound quality. As a result, the voice heard by the far-end user increases the discomfort of the far-end user due to the change in the variable analog gain α1.

  On the other hand, when the variable analog gain α1 is changed at the zero cross timing as in the present embodiment shown in FIG. 8, the output of the analog amplifier section 32 hardly changes depending on the timing of the change. Therefore, since the voice heard by the far-end user does not change abruptly, the discomfort of the far-end user due to the change in the variable analog gain α1 can be reduced.

  FIG. 9 is a diagram for explaining a time change of a signal. The upper graph in FIG. 9 is a diagram illustrating the input analog audio signal SS22 output from the analog amplifier unit 32. The middle graph in FIG. 9 is a diagram showing the input digital audio signal SS23 output from the A / D converter 34. The lower graph in FIG. 9 is a diagram illustrating the input digital audio signal SS24 output from the digital amplifier unit 24. In the outputs after the zero cross in each graph of FIG. 9, the dotted line indicates the signal before the gain change, and the solid line indicates the signal after the gain change. In each graph, the horizontal axis indicates time, and the vertical axis indicates intensity. In addition, the relative value of the intensity | strength of the vertical axis | shaft in each graph differs.

  Between the upper graph and the middle graph, the analog gain α3 output by the control unit 30, the variable analog gain α1 of the analog amplifier unit 32, and the sampling frequency for detecting the zero cross are shown in order from the top. A variable digital gain β1 of the digital amplifier unit 24 is shown between the middle graph and the lower graph.

  As shown in the upper graph of FIG. 9, the control unit 30 changes the analog gain α3 at time T1 and outputs the analog gain α3 to the timing control unit 28. The timing control unit 28 stores the analog gain α3 at the input time T1, but does not output the analog gain α3 to the analog amplifier unit 32. Thereafter, the analog amplifier unit 32 detects a zero cross where the intensity of the input analog audio signal SS22 becomes “0”, and outputs the detected fact to the timing control unit 28. Strictly speaking, the analog amplifier unit 32 detects at a timing shifted by time DT1 from the zero cross within a sampling cycle range for detecting the zero cross. Therefore, the zero cross timing here is a time within the range of the sampling period from the zero cross timing. When the timing control unit 28 acquires that the zero cross has been detected, the timing control unit 28 outputs the analog gain α3 to the analog amplifier unit 32.

  When a new analog gain α3 is input, the analog amplifier unit 32 changes the variable analog gain α1 to the analog gain α3. As a result, the output of the analog amplifier unit 32 changes from a curve indicated by a dotted line in the upper part of FIG. 9 to a curve indicated by a solid line.

  Next, the A / D conversion unit 34 digitally converts the input analog audio signal SS22 input from the analog amplifier unit 32 and outputs it. Here, the A / D converter 34 requires time DT2 for digital conversion. As a result, the A / D converter 34 outputs the input digital audio signal SS23 at a timing shifted by time DT2 with respect to the input analog audio signal SS22. Therefore, the timing at which the input digital audio signal SS23 output from the A / D conversion unit 34 is switched with the switching of the variable analog gain α1 of the analog amplifier unit 32 is shifted by the time DT2.

  Next, the digital amplifier unit 24 outputs the input digital audio signal SS23 obtained by attenuating the input digital audio signal SS23 input from the A / D conversion unit 34 with the variable digital gain β1. Here, the digital gain calculator 54 outputs a new digital gain β2 after the time DT2 required for the digital conversion by the A / D converter 34 rather than the variable analog gain α1 of the analog amplifier 32 changing. . Therefore, the digital amplifier unit 24 changes the variable digital gain β1 at the zero cross timing of the output input digital audio signal SS23.

  FIG. 10 is a flowchart of audio signal processing by the audio signal processing apparatus 10. The flowchart on the left in FIG. 10 shows processing by the conversion unit 22, the digital amplifier unit 24, and the echo canceller unit 26. The flowchart on the right side in FIG. 10 describes processing by the control unit 30 and the timing control unit 28. Note that a computer having a CPU or the like may execute the audio signal processing shown in FIG. 10 by reading an audio signal processing program. The audio signal processing method will be described with reference to FIG.

  As shown in the left diagram of FIG. 10, in the audio signal processing, first, the analog amplifier unit 32 acquires the input analog audio signal SS22 via the audio input unit 20 (ST102). The analog amplifier unit 32 determines whether or not the input analog audio signal SS21 has crossed zero (ST104). If the analog amplifier unit 32 determines that the input analog audio signal SS21 has zero-crossed (ST104: Yes), the analog amplifier unit 32 outputs a detection signal DS indicating that the zero-cross has been detected to the timing control unit 28 (ST106). After changing the setting of the variable analog gain α1 to the new analog gain α3 input from the timing control unit 28 (ST108), the analog amplifier unit 32 amplifies the input analog audio signal SS21 with the changed variable analog gain α1. Input analog audio signal SS22 is output to A / D converter 34 (ST110).

  On the other hand, when the analog amplifier unit 32 does not detect the zero cross (ST104: No), the input analog audio signal obtained by amplifying the input analog audio signal SS21 with the current variable analog gain α1 without executing steps ST106 and ST108. SS22 is output to A / D converter 34 (ST110).

  The A / D converter 34 outputs the input digital audio signal SS23 obtained by digitally converting the input analog audio signal SS22 to the digital amplifier 24 (ST112). The digital amplifier unit 24 sets the variable digital gain β1 (ST114). Here, if the new digital gain β2 is not input from the digital gain calculation unit 54, the digital amplifier unit 24 maintains the current variable digital gain β1. On the other hand, if a new digital gain β2 is input from the digital gain calculation unit 54, the digital amplifier unit 24 sets the new digital gain β2 to the variable digital gain β1.

  The digital amplifier 24 outputs the input digital audio signal SS24 obtained by attenuating the input digital audio signal SS23 with the variable digital gain β1 to the subtractor 38 of the echo canceller 26 (ST116). The echo canceller 26 subtracts the pseudo echo signal SS30 output from the adaptive filter 36 from the input digital audio signal SS24 input to the subtractor 38, and outputs the far-end output audio signal SS20 from which the echo has been canceled to the input / output unit 12. (ST118). Thereafter, the input / output unit 12 outputs the far-end output audio signal SS20 to the far-end user's audio signal processing device or the like (ST120).

  As shown in the right diagram of FIG. 10, the first digital amplifier unit 40 of the control unit 30 acquires the far-end input digital audio signal SS10 from the far-end input side of the input / output unit 12, and then uses the echo gain γ3 to The pseudo echo signal SS38 obtained by amplifying or attenuating the input digital audio signal SS10 is output to the first peak detector 42 (ST202). The second digital amplifier unit 44 of the control unit 30 acquires the input digital audio signal SS23 from the A / D conversion unit 34, and then an input digital audio signal SS39 obtained by amplifying or attenuating the input digital audio signal SS23 with the variable digital gain α2. Is output to the second peak detector 46 (ST204).

  Next, the first peak detection unit 42 detects the peak of the pseudo echo signal SS38 output from the first digital amplifier unit 40, and outputs it to the comparator 48 and the selector 50 as the first peak signal SS41. The second peak detection unit 46 detects the peak of the input digital audio signal SS39 output from the second digital amplifier unit 44, and outputs it to the comparator 48 and the selector 50 as the second peak signal SS42 (ST206).

  The comparator 48 compares the first peak signal SS41 and the second peak signal SS42, and outputs determination information JS indicating a peak signal having a high intensity to the selector 50. Based on determination information JS, selector 50 outputs the peak signal having the higher intensity to AGC 52 (ST208).

  In the AGC 52, the target gain setting unit 56 sets the target gain μ based on the peak signal input from the selector 50 and outputs the target gain μ to the attack release setting unit 58. Attack release setting section 58 sets analog gain α3 and outputs the same to timing control section 28 (ST210).

  The timing control unit 28 determines whether or not the zero cross is based on the zero cross detection signal DS input from the analog amplifier unit 32 (ST212). When the detection signal DS is not input, the timing control unit 28 determines that it is not zero crossing (ST212: No), and repeats step ST202 and subsequent steps without changing the analog gain α3.

  On the other hand, when the detection signal is input, the timing control unit 28 determines zero cross (ST212: Yes), and calculates the analog gain α3 input from the control unit 30 as the digital gain calculation of the analog amplifier unit 32 and the control unit 30. Output to unit 54 (ST214).

  The digital gain calculation unit 54 sets the digital gain β2 based on the analog gain α3 input from the timing control unit 28 (ST216). Thereafter, the digital gain calculation unit 54 is in a standby state until the time DT2 elapses after the analog gain α3 is input from the timing control unit 28 (ST218: No). If the digital gain calculation unit 54 determines that the time DT2 has elapsed (ST218: Yes), it outputs the digital gain β2 to the digital amplifier unit 24 (ST220). After this, step ST202 and subsequent steps are repeated.

  As described above, in the audio signal processing device 10, the control unit 30 changes the variable analog gain α <b> 1 so that the input analog audio signal SS <b> 22 amplified by the analog amplifier unit 32 is converted into the dynamic of the A / D conversion unit 34. It is controlled to fit in the range. Thereby, the audio signal processing device 10 can digitally convert the input analog audio signal SS22 in a larger range of the dynamic range of the A / D converter 34. As a result, the audio signal processing device 10 can improve the S / N ratio.

  In the audio signal processing device 10, the variable analog gain α1 is changed at the zero cross timing of the input analog audio signal SS22. Thereby, since the audio signal processing device 10 can suppress a rapid change in the far-end output audio signal SS20, it is possible to reduce the discomfort of the user at the far end.

  In the audio signal processing device 10, the control unit 30 detects the peak of either the pseudo echo signal SS38 or the input digital audio signal SS39, and controls the variable analog gain α1 of the analog amplifier unit 32 based on the peak. ing. Therefore, the control unit 30 can gently change the variable analog gain α1 regardless of a sudden change in the intensity of the pseudo echo signal SS38 or the input digital audio signal SS39.

  Further, in the audio signal processing device 10, the control unit 30 controls the variable analog gain α1 with a signal having a high intensity among the pseudo echo signal SS38 or the input digital audio signal SS39. Here, in general, when an echo is generated, the pseudo echo signal SS38 input through the housing or the like is larger than the input digital audio signal SS39. Therefore, the control unit 30 can control the region where the variable analog gain α1 is large by the pseudo echo signal SS38. On the other hand, when no echo is generated, the input digital audio signal SS39 is larger than the pseudo echo signal SS38. Therefore, the control unit 30 can control the region where the variable analog gain α1 is small by the input digital audio signal SS39. Thereby, the control unit 30 can control the variable analog gain α1 with higher accuracy.

  In the audio signal processing device 10, the control unit 30 generates a pseudo echo signal SS 38 from the far-end input digital audio signal SS 10 before being output from the audio output unit 18. Thereby, since the control part 30 can predict an echo, it is not late for the echo input from the audio | voice input part 20, and it suppresses distortion of an echo, Variable analog gain (alpha) 1 of the analog amplifier part 32 Can be controlled.

  In the audio signal processing apparatus 10, the digital amplifier unit 24 outputs an input digital audio signal SS 24 obtained by attenuating the input digital audio signal SS 23 amplified by the analog amplifier unit 32 to the echo canceller unit 26. Further, the control unit 30 sets the variable digital gain β1 of the digital amplifier unit 24 to the reciprocal of the difference Δα from the initial value α0. As a result, the echo canceller 26 can remove echo from the input digital audio signal SS24 having substantially the same intensity as that before being amplified by the analog amplifier 32. Therefore, the echo canceller unit 26 does not need to change the intensity of the pseudo echo signal SS30 in accordance with the change of the variable analog gain α1 of the analog amplifier unit 32. Thereby, the echo canceller 26 can remove the echo while reducing the distortion of the echo without complicating the configuration.

  In the audio signal processing device 10, the control unit 30 changes the variable digital gain β1 by shifting the time required for the digital conversion by the A / D conversion unit 34 from the timing at which the variable analog gain α1 is changed. Accordingly, the control unit 30 can match the timing at which the variable analog gain α1 changes with the timing at which the variable digital gain β1 changes in the input digital audio signal SS23.

  Numerical values such as the arrangement, connection relationship, function, number, and the like of each configuration of the above-described embodiments may be changed as appropriate.

  In the above-described embodiment, the control unit 30 changes the variable analog gain α1 of the analog amplifier unit 32 to change the output of the input analog audio signal SS22 amplified by the analog amplifier unit 32 to the A / D conversion unit 34. Although an example of controlling so as to fall within the dynamic range has been given, the present invention is not limited to this. The control unit 30 may perform control so that the input analog audio signal SS <b> 21 falls within the dynamic range of the conversion unit 22. For example, the control unit 30 controls the dynamic range of the A / D conversion unit 34 so that the output of the input analog audio signal SS22 amplified by the analog amplifier unit 32 falls within the dynamic range of the A / D conversion unit 34. You may control to. Also by this, the control unit 30 can perform control so that the input analog audio signal SS <b> 21 falls within the dynamic range of the conversion unit 22. Here, in the 8-bit A / D converter 34, when the dynamic range is set to −2 V to +2 V (analog value per digital value 1), the resolution of the output digital value is “1/64 V (= 4 V / 256). " Further, when the dynamic range is −1V to + 1V, the resolution is “1 / 128V”. Such a change in the dynamic range can be realized by changing the maximum measurement voltage supplied to the A / D converter 34. When the control unit 30 controls the dynamic range of the A / D conversion unit 34, the analog amplifier unit 32 may be omitted.

  In the above-described embodiment, the analog amplifier unit 32 amplifies the input analog audio signal SS21. However, the analog amplifier unit 32 may attenuate the input analog audio signal SS21. In the above-described embodiment, the digital amplifier unit 24 attenuates the input digital audio signal SS23. However, the digital amplifier unit 24 may amplify the input digital audio signal SS23.

  In the above-described embodiment, the timing control unit 28 changes the variable analog gain α1 of the analog amplifier unit 32 at the zero-cross timing of the input analog audio signal SS21. However, the timing at which the variable analog gain α1 is changed is appropriately changed. It's okay. The control unit 30 preferably controls the change timing of the variable digital gain β1 of the digital amplifier unit 24 in accordance with the change timing of the change of the variable analog gain α1 of the analog amplifier unit 32.

  In the above-described embodiment, an example in which the control unit 30 sets the variable analog gain α1 of the analog amplifier unit 32 using the two target gains μ1 and μ2 has been described, but the number of target gains μ is limited to two. 3 or more may be sufficient. Alternatively, the target gain μ may be calculated from a mathematical expression such as a polynomial.

  In the above-described embodiment, the example in which the first digital amplifier unit 40 of the control unit 30 generates the pseudo echo signal SS38 from the predetermined echo gain γ3 has been described. However, the control unit 30 is adapted to the adaptation of the echo canceller unit 26. The pseudo echo signal SS30 may be acquired from the filter 36.

  In the above-described embodiment, the control unit 30 controls the variable digital gain β1 of the digital amplifier unit 24 to be the inverse of the difference Δα from the initial value α0, but the relationship between the variable digital gain β1 and the difference Δα is this. Not limited to. For example, the control unit 30 may control the value obtained by making the difference Δα inversely proportional to the variable digital gain β1. Thereby, even if the control part 30 changes the dynamic range of the conversion part 22, the gain of the signal which passes the conversion part 22 and the digital amplifier part 24 can be suppressed. Thereby, the echo canceller 26 can easily cope with the amplification by the analog amplifier 32.

  FIG. 11 shows an example of a hardware configuration of a computer 1900 according to this embodiment. A computer 1900 according to the present embodiment is an example of an apparatus that executes an audio signal processing program. The computer 1900 includes a CPU 2000 and a RAM 2020 connected to each other by a host controller 2082, a communication interface 2030 connected to the host controller 2082 by an input / output controller 2084, and an input / output unit having a hard disk drive 2040. A legacy input / output unit having a ROM 2010, a memory drive 2050, and an input / output chip 2070 connected to the output controller 2084;

  The host controller 2082 connects the RAM 2020 and the CPU 2000 that accesses the RAM 2020 at a high transfer rate. The CPU 2000 operates based on programs stored in the ROM 2010 and the RAM 2020 and controls each unit.

  The input / output controller 2084 connects the host controller 2082 to the communication interface 2030 and the hard disk drive 2040 that are relatively high-speed input / output devices. The communication interface 2030 communicates with other devices via a network. The hard disk drive 2040 stores programs and data such as a display program used by the CPU 2000 in the computer 1900.

  The input / output controller 2084 is connected to the ROM 2010, the memory drive 2050, and the relatively low-speed input / output device of the input / output chip 2070. The ROM 2010 stores a boot program that the computer 1900 executes at startup and / or a program that depends on the hardware of the computer 1900. The memory drive 2050 reads a program or data such as a display program from the memory card 2090 and provides it to the hard disk drive 2040 via the RAM 2020. The input / output chip 2070 connects the memory drive 2050 to the input / output controller 2084, and also connects various input / output devices to the input / output controller 2084 via, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like. Connect to.

  A program provided to the hard disk drive 2040 via the RAM 2020 is stored in a recording medium such as a memory card 2090 or an IC card and provided by a user. A program such as a display program is read from a recording medium, installed in the hard disk drive 2040 in the computer 1900 via the RAM 2020, and executed by the CPU 2000.

  A program installed in the computer 1900 and causing the computer 1900 to function as the audio signal processing apparatus 10 includes an audio input module, a conversion module, a digital amplifier module, and a control module. These programs or modules work on the CPU 2000 or the like to cause the computer 1900 to function as an audio input module, a conversion module, a digital amplifier module, and a control module.

  The information processing described in these programs is read by the computer 1900, so that the software and the above-described various hardware resources cooperate with each other as a voice input module, a conversion module, a digital amplifier module, And it functions as a control module. And the specific audio | voice signal processing apparatus 10 according to a use purpose is constructed | assembled by implement | achieving the calculation or the process of the information according to the use purpose of the computer 1900 in this embodiment by these concrete means.

  As an example, when communication is performed between the computer 1900 and an external device or the like, the CPU 2000 executes a communication program loaded on the RAM 2020 and executes a communication interface based on the processing content described in the communication program. A communication process is instructed to 2030. Under the control of the CPU 2000, the communication interface 2030 reads transmission data stored in a transmission buffer area or the like provided on a storage device such as the RAM 2020, the hard disk drive 2040, or the memory card 2090, and transmits it to the network. The reception data received from the network is written into a reception buffer area or the like provided on the storage device. As described above, the communication interface 2030 may transfer transmission / reception data to / from the storage device by a DMA (direct memory access) method. Instead, the CPU 2000 transfers the storage device or the communication interface 2030 as a transfer source. The transmission / reception data may be transferred by reading the data from the data and writing the data to the communication interface 2030 or the storage device of the transfer destination.

  In addition, the CPU 2000 causes the RAM 2020 to read all or necessary portions from among files or databases stored in an external storage device such as the hard disk drive 2040 and the memory drive 2050 (memory card 2090) into the RAM 2020 by DMA transfer or the like. Various processes are performed on the data on the RAM 2020. Then, CPU 2000 writes the processed data back to the external storage device by DMA transfer or the like. In such processing, since the RAM 2020 can be regarded as temporarily holding the contents of the external storage device, in the present embodiment, the RAM 2020 and the external storage device are collectively referred to as a memory, a storage unit, or a storage device. Various types of information such as various programs, data, tables, and databases in the present embodiment are stored on such a storage device and are subjected to information processing. Note that the CPU 2000 can also store a part of the RAM 2020 in the cache memory and perform reading and writing on the cache memory. Even in such a form, the cache memory bears a part of the function of the RAM 2020. Therefore, in the present embodiment, the cache memory is also included in the RAM 2020, the memory, and / or the storage device unless otherwise indicated. To do.

  In addition, the CPU 2000 performs various operations, such as various operations, information processing, condition determination, information search / replacement, etc., described in the present embodiment, specified for the data read from the RAM 2020 by the instruction sequence of the program. Is written back to the RAM 2020. For example, when performing the condition determination, the CPU 2000 determines whether the various variables shown in the present embodiment satisfy the conditions such as large, small, above, below, equal, etc., compared to other variables or constants. When the condition is satisfied (or not satisfied), the program branches to a different instruction sequence or calls a subroutine. Further, the CPU 2000 can search for information stored in a file or database in the storage device.

  The program or module shown above may be stored in an external recording medium. As the recording medium, in addition to the memory card 2090, an optical recording medium such as DVD or CD, a magneto-optical recording medium such as MO, a tape medium, a semiconductor memory such as an IC card, or the like can be used. Further, a storage device such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the computer 1900 via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Audio | voice signal processing apparatus 12 Input / output part 14 D / A conversion part 16 Output amplifier 18 Audio | voice output part 20 Audio | voice input part 22 Conversion part 24 Digital amplifier part 26 Echo canceller part 28 Timing control part 30 Control part 32 Analog amplifier part 34 A / D conversion unit 36 Adaptive filter 38 Subtractor 40 First digital amplifier unit 42 First peak detection unit 44 Second digital amplifier unit 46 Second peak detection unit 48 Comparator 50 Selector 52 AGC
54 Digital Gain Calculation Unit 56 Target Gain Setting Unit 58 Attack Release Setting Unit 60 D-FF Circuit 70 DSP
72 CODEC
1900 Computer 2000 CPU
2010 ROM
2020 RAM
2030 Communication interface 2040 Hard disk drive 2050 Memory drive 2070 Input / output chip 2082 Host controller 2084 Input / output controller 2090 Memory card

Claims (14)

An audio input unit for outputting an input analog audio signal corresponding to the input audio;
A converter that digitally converts the input analog audio signal within a dynamic range and outputs the digital audio signal as an input digital audio signal;
A control unit for controlling the conversion unit ,
The converter is
An analog amplifier for amplifying or attenuating the input analog audio signal;
An A / D converter that digitally converts the amplified or attenuated input analog audio signal;
The said control part is an audio | voice signal processing apparatus which sets the analog gain of the said analog amplifier part based on either the said input digital audio | voice signal and the pseudo echo signal calculated from the external audio | voice signal input from the outside . The control unit has a first peak signal set from a peak of the pseudo echo signal and a second peak signal calculated from a peak of the input digital audio signal attenuated by an inverse of the analog gain. the large peak signal, the audio signal processing apparatus according to claim 1 for setting the analog gain. An audio input unit for outputting an input analog audio signal corresponding to the input audio;
A converter that digitally converts the input analog audio signal within a dynamic range and outputs the digital audio signal as an input digital audio signal;
A control unit for controlling the conversion unit ,
The converter is
An analog amplifier for amplifying or attenuating the input analog audio signal;
An A / D converter that digitally converts the amplified or attenuated input analog audio signal;
The control unit controls the analog gain of the analog amplifier unit to adapt to the intensity of the input analog audio signal,
The analog amplifier unit is an audio signal processing device that changes the analog gain at a timing at which the intensity of the input analog audio signal crosses zero . A digital amplifier for amplifying or attenuating the input digital audio signal;
The controller is
While controlling the analog gain of the analog amplifier unit,
The audio signal processing device according to any one of claims 1 to 3, wherein a digital gain of the digital amplifier unit is controlled according to the analog gain set in the analog amplifier unit. An audio input unit for outputting an input analog audio signal corresponding to the input audio;
A converter that digitally converts the input analog audio signal within a dynamic range and outputs the digital audio signal as an input digital audio signal;
A control unit for controlling the conversion unit ;
A digital amplifier unit that amplifies or attenuates the input digital audio signal ;
The converter is
An analog amplifier for amplifying or attenuating the input analog audio signal;
An A / D converter that digitally converts the amplified or attenuated input analog audio signal;
The controller is
Controlling the analog gain of the analog amplifier unit to adapt to the intensity of the input analog audio signal, and controlling the digital gain of the digital amplifier unit according to the analog gain set in the analog amplifier unit,
The control unit acquires the change timing when the analog gain of the analog amplifier unit is changed from the analog amplifier unit, and controls the change timing of the digital gain of the digital amplifier unit based on the change timing. Audio signal processing device. Wherein the control unit, the audio signal processing apparatus according to claim 4 or 5 for controlling the value obtained by inversely proportional analog gain of the analog amplifier unit as the digital gain of the digital amplifier unit. The audio signal processing apparatus according to claim 1, further comprising an echo canceller that cancels echoes from the input digital audio signal. The audio signal processing device according to any one of claims 1 to 7 , further comprising an input / output unit that transmits and receives information to and from another device. An audio signal processing method for processing input audio by an audio signal processing device,
An audio input stage for outputting an input analog audio signal corresponding to the input audio;
A conversion step of digitally converting the input analog audio signal within a dynamic range and outputting as an input digital audio signal;
A control stage for controlling the conversion in the conversion stage ,
The converting step includes
An analog amplifier stage for amplifying or attenuating the input analog audio signal;
An A / D conversion stage for digitally converting the amplified or attenuated input analog audio signal;
The audio signal processing method in which the control step sets an analog gain in the analog amplifier step based on either the input digital audio signal or a pseudo echo signal calculated from an external audio signal input from the outside . An audio signal processing method for processing input audio by an audio signal processing device,
An audio input stage for outputting an input analog audio signal corresponding to the input audio;
A conversion step of digitally converting the input analog audio signal within a dynamic range and outputting as an input digital audio signal;
A control stage for controlling the conversion in the conversion stage ,
The converting step includes
An analog amplifier stage for amplifying or attenuating the input analog audio signal;
An A / D conversion stage for digitally converting the amplified or attenuated input analog audio signal;
The control stage controls the analog gain in the analog amplifier stage to adapt to the intensity of the input analog audio signal;
In the analog amplifier stage, the analog gain is changed at a timing when the intensity of the input analog audio signal crosses zero . An audio signal processing method for processing input audio by an audio signal processing device,
An audio input stage for outputting an input analog audio signal corresponding to the input audio;
A conversion step of digitally converting the input analog audio signal within a dynamic range and outputting as an input digital audio signal;
A control stage for controlling the conversion in the conversion stage;
A digital amplifier stage for amplifying or attenuating the input digital audio signal ;
The converting step includes
An analog amplifier stage for amplifying or attenuating the input analog audio signal;
An A / D conversion stage for digitally converting the amplified or attenuated input analog audio signal;
The control step includes
Controlling the analog gain in the analog amplifier stage to adapt to the intensity of the input analog audio signal, and controlling the digital gain in the digital amplifier stage according to the analog gain set for the analog amplifier stage,
The control step acquires the change timing of changing the analog gain in the analog amplifier step from the analog amplifier step, and controls the change timing of the digital gain in the digital amplifier step based on the change timing. Audio signal processing method. An audio signal processing program for causing a computer to function as an audio signal processing device,
A voice input function that outputs an input analog voice signal according to the input voice;
A conversion function for digitally converting the input analog audio signal within a dynamic range and outputting it as an input digital audio signal;
Causing the computer to execute a control function for controlling the conversion function ;
The conversion function is
An analog amplifier function for amplifying or attenuating the input analog audio signal;
An A / D conversion function for digitally converting the input analog audio signal amplified or attenuated,
The control function is an audio signal processing program that sets an analog gain of the analog amplifier function based on either the input digital audio signal or a pseudo echo signal calculated from an external audio signal input from the outside . An audio signal processing program for causing a computer to function as an audio signal processing device,
A voice input function that outputs an input analog voice signal according to the input voice;
A conversion function for digitally converting the input analog audio signal within a dynamic range and outputting it as an input digital audio signal;
Causing the computer to execute a control function for controlling the conversion function ;
The conversion function is
An analog amplifier function for amplifying or attenuating the input analog audio signal;
An A / D conversion function for digitally converting the input analog audio signal amplified or attenuated,
The control function controls the analog gain of the analog amplifier function to adapt to the intensity of the input analog audio signal,
The analog amplifier function is an audio signal processing program for changing the analog gain at a timing when the intensity of the input analog audio signal crosses zero . An audio signal processing program for causing a computer to function as an audio signal processing device,
A voice input function that outputs an input analog voice signal according to the input voice;
A conversion function for digitally converting the input analog audio signal within a dynamic range and outputting it as an input digital audio signal;
A control function for controlling the conversion function ;
A digital amplifier function for amplifying or attenuating the input digital audio signal ;
The conversion function is
An analog amplifier function for amplifying or attenuating the input analog audio signal;
An A / D conversion function for digitally converting the input analog audio signal amplified or attenuated,
The control function is
Controlling the analog gain of the analog amplifier function to adapt to the intensity of the input analog audio signal, and controlling the digital gain of the digital amplifier function according to the analog gain set in the analog amplifier function,
The control function acquires a change timing at which the analog gain of the analog amplifier function is changed from the analog amplifier function, and controls a change timing of the digital gain of the digital amplifier function based on the change timing. Audio signal processing program.

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