JP5040507B2 - Automatic sound quality control device and integrated circuit - Google Patents

Description

  The present invention relates to an automatic sound quality control device for automatically controlling sound quality in order to compensate for noise masking on a multi-channel audio signal, and an integrated circuit.

  The conventional automatic sound quality control apparatus has changed the frequency characteristics of the audio signal of each channel in order to compensate for masking due to noise (see, for example, Patent Document 1).

As a technique for changing the frequency characteristic of an audio signal of a specific channel, a processing circuit that corrects the frequency characteristic of only the center channel audio signal among multi-channel audio signals with an equalizer is known (for example, Patent Document 2). See).
JP 09-148867 A JP 2004-266604 A

  However, the automatic sound quality control device described in Patent Document 1 has a problem that a calculation amount is required to change the frequency characteristics of the audio signal of each channel. Further, there is a problem that an equalizer, which is expensive hardware, is required for each channel in order to satisfy the calculation amount requirement.

  Further, in the processing circuit described in Patent Document 2, equalization is performed only on the audio signal of the center channel including the audio component, and processing on the audio signals of other channels is not performed. Therefore, although the amount of calculation is reduced, there is a problem in that the sound quality balance between the audio signal of the channel to be equalized and the audio signal of the channel not to be equalized is poor, and the effect of compensating for masking due to noise may be impaired.

  An object of the present invention is to reduce the amount of calculation and to make the hardware inexpensive, and to compensate for masking due to noise in comparison with a conventional automatic sound quality control device that changes frequency characteristics for all channels. An object of the present invention is to provide an automatic sound quality control device that does not significantly impair the effect.

  The automatic sound quality control apparatus according to the present invention calculates a compensation amount for compensating for masking of a multi-channel audio signal by a noise signal for each frequency band, and a volume component which is an average value of the compensation amount, and the compensation amount A frequency unit that calculates a frequency component obtained by subtracting each of the volume components from the frequency component, and a frequency characteristic that changes only a frequency characteristic of an audio signal of a specific channel included in the multi-channel based on the frequency component calculated by the calculation unit The frequency characteristic is changed by the changing unit, the volume changing unit that changes the volume of the audio signal of all the channels included in the multi-channel based on the volume component calculated by the calculating unit, and the frequency characteristic changing unit, The audio signal of the specific channel whose volume has been changed by the volume changing unit, and the volume changing unit And an outputting unit for outputting the audio signal of the channel other than the specific channel that has changed the volume as a sound like.

  The present invention reduces the amount of calculation compared to an automatic sound quality control device that changes the frequency characteristics of audio signals of all channels, makes the hardware inexpensive, and does not significantly impair the effect of compensating for masking due to noise in terms of hearing. A control device can be provided.

(First embodiment)
Hereinafter, an automatic sound quality control apparatus 1 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an automatic sound quality control apparatus 1 according to the first embodiment of the present invention. In FIG. 1, an automatic sound quality control apparatus 1 includes an input unit 10 to which a multi-channel audio signal is input, and a first A / D converter unit (Analog to Digital Converter) that converts an audio signal from an analog signal to a digital signal. 11, a microphone 12 that takes in noise and converts it into a noise signal, a second A / D converter unit 13 that converts the noise signal from an analog signal into a digital signal, and a DSP (Digital Signal Processor) that compensates for noise in the audio signal ) 14, a D / A converter unit (Digital to Analog Converter) 15 that converts the audio signal from a digital signal to an analog signal, an amplifier unit 16 that amplifies the audio signal, and outputs the audio signal as sound And an output unit 17.

  The input unit 10 includes a plurality of input terminals. Electronic devices such as audio, television and radio tuners are connected to the input terminals of the input unit 10. An audio signal is input to the input unit 10 for each channel from the electronic device. The input unit 10 is connected to the first A / D converter unit 11. The input unit 10 outputs the audio signal input from the electronic device to the first A / D converter unit 11 for each channel.

  The first A / D converter unit 11 includes a plurality of A / D converters. Each A / D converter included in the first A / D converter unit 11 is connected to each input terminal included in the input unit 10. An audio signal is input to the first A / D converter unit 11 from the input unit 10 for each channel. The first A / D converter unit 11 converts an audio signal input for each channel from an analog signal to a digital signal. The first A / D converter unit 11 is connected to the DSP 14. The first A / D converter unit 11 outputs the audio signal converted into the digital signal to the DSP 14 for each channel.

  The microphone 12 takes in noise and converts it into a noise signal. This noise signal is an analog signal. The microphone 12 is connected to the second A / D converter unit 13. The microphone 12 inputs a noise signal to the second A / D converter unit 13.

  The second A / D converter unit 13 includes one A / D converter. A microphone 12 is connected to the second A / D converter unit 13. A noise signal is input from the microphone 12 to the second A / D converter unit 13. The second A / D converter unit 13 converts the noise signal from an analog signal to a digital signal. The second A / D converter unit 13 is connected to the DSP 14. The second A / D converter unit 13 outputs the noise signal converted into the digital signal to the DSP 14.

  A first A / D converter unit 11 and a second A / D converter unit 13 are connected to the DSP 14. An audio signal is input to the DSP 14 from the first A / D converter unit 11 for each channel. The signal input to the DSP 14 is a digital signal. The DSP 14 further receives a noise signal converted into a digital signal from the second A / D converter unit 13. The DSP 14 compensates the noise of the audio signal for each channel based on the audio signal input for each channel and the input noise signal. The DSP 14 is connected to the D / A converter unit 15. The DSP 14 outputs the noise-compensated audio signal to the D / A converter unit 15 for each channel.

  The D / A converter unit 15 includes a plurality of D / A converters. A DSP 14 is connected to each D / A converter included in the D / A converter unit 15. The D / A converter unit 15 receives an audio signal whose noise is compensated for each channel from the DSP 14. The audio signal input to the D / A converter unit 15 is a digital signal. The D / A converter unit 15 converts the audio signal input for each channel from a digital signal to an analog signal. The D / A converter unit 15 is connected to the amplifier unit 16. The D / A converter unit 15 outputs an audio signal converted from a digital signal to an analog signal to the amplifier unit 16 for each channel.

  The amplifier unit 16 includes a plurality of amplifiers. Each amplifier provided in the amplifier unit 16 is connected to each D / A converter included in the D / A converter unit 15. The amplifier unit 16 receives an audio signal whose noise is compensated for each channel from the D / A converter unit 15. The audio signal input to the amplifier unit 16 is an analog signal. The amplifier unit 16 amplifies the audio signal input for each channel. The amplifier unit 16 is connected to the output unit 17. The amplifier unit 16 outputs the audio signal amplified for each channel to the output unit 17 for each channel.

  The output unit 17 includes a plurality of speakers. Each amplifier included in the amplifier unit 16 is connected to each speaker included in the output unit 17. The audio signal amplified for each channel is input from the amplifier unit 16 to the output unit 17. The output unit 17 outputs the audio signal amplified for each channel as sound for each speaker.

  Hereinafter, how the audio signal is compensated through the DSP 14 will be described.

  The DSP 14 includes various functional blocks including a calculation unit 18, an equalizer unit 19, and a level adjustment unit 20.

  Each A / D converter included in the first A / D converter unit 11 and the second A / D converter unit 13 are connected to the calculation unit 18. The calculation unit 18 receives an audio signal converted into a digital signal for each channel from the first A / D converter unit 11. Further, the noise signal converted into the digital signal is input to the calculation unit 18 from the second A / D converter unit 13.

  Based on the audio signal input for each channel from the first A / D converter unit 11 and the noise signal input from the second A / D converter unit 13, the calculation unit 18 calculates the compensation amount and the frequency. The component and the volume component are calculated. Hereinafter, the calculation method will be described. The calculation unit 18 adds and synthesizes the input audio signals of the respective channels, and divides the added and synthesized audio signal into predetermined frequency bands. The total number of sections is N. N is an integer greater than 1. The frequency band section i can take an integer value of 1 or more and N or less. The calculating unit 18 calculates the compensation amount C (i) of the signal corresponding to the section i in the summed audio signal for all the sections 1 to N.

  Next, the calculation unit 18 calculates the volume component ν based on the compensation amount C (i) calculated for each section i and the following (Equation 1). The volume component ν is a value obtained by adding the compensation amount C (i) of each section i for all sections 1 to N and dividing by the total number N of sections. That is, the volume component ν is an average value of the compensation amount C (i). The volume component ν is not a value for each section i, but a single value common to each section i.

  Next, the calculation unit 18 calculates a frequency component C ′ (i) for each section i. The frequency component C ′ (i) is calculated based on the compensation amount C (i) calculated for each section i, the calculated volume component ν, and C ′ (i) = C (i) −ν. Is done.

  The calculation unit 18 is connected to the equalizer unit 19. The calculation unit 18 outputs the frequency component C ′ (i) calculated for each section i to the equalizer unit 19. The calculation unit 18 is connected to the level adjustment unit 20. The calculation unit 18 outputs the volume component ν to the level adjustment unit 20.

  The equalizer unit 19 includes a plurality of equalizers. Each equalizer provided in the equalizer unit 19 is connected to each A / D converter to which an audio signal of a specific channel is input among the plurality of A / D converters provided in the first A / D converter unit 11. An audio signal of a specific channel is input from the first A / D converter unit 11 to the equalizer unit 19. The specific channel will be described later. Moreover, the calculation part 18 is connected to each equalizer with which the equalizer part 19 is provided, respectively. The frequency component C ′ (i) is input from the calculation unit 18 to the equalizer unit 19. The equalizer unit 19 divides the audio signal of the specific channel input from the first A / D converter unit 11 into the same frequency band as the frequency band included in each division i used in the calculation unit 18. The equalizer unit 19 raises the level of each frequency component C ′ (i) with respect to the signal of the portion corresponding to each section i (1 ≦ i ≦ N) in the audio signal of the specific channel. Thereby, the equalizer unit 19 changes the frequency characteristic of the audio signal of the specific channel. The equalizer unit 19 is connected to the level adjustment unit 20. The equalizer unit 19 outputs the audio signal of the specific channel whose frequency characteristic is changed to the level adjusting unit 20 for each channel.

  The level adjustment unit 20 includes a plurality of level adjusters. Each level adjuster provided in the level adjustment unit 20 is connected to each equalizer provided in the equalizer unit 19. An audio signal of a specific channel whose frequency characteristics are changed is input from the equalizer unit 19 to the level adjustment unit 20. Each A / D converter to which audio signals of channels other than the specific channel among a plurality of A / D converters provided in the first A / D converter unit 11 are input is connected to the level adjusting unit 20. An audio signal of a channel other than the specific channel is input from the first A / D converter unit 11 to the level adjustment unit 20. A calculation unit 18 is connected to each level adjuster provided in the level adjustment unit 20. The level adjustment unit 20 receives the volume component ν from the calculation unit 18. The level adjustment unit 20 adds the volume component ν input from the calculation unit 18 to the audio signal of each channel input from the first A / D converter unit 11 and the equalizer unit 19. Thereby, the level adjustment unit 20 changes the volume of the audio signal of each channel input from the first A / D converter unit 11 and the equalizer unit 19. The level adjustment unit 20 is connected to the D / A converter unit 15. The level adjustment unit 20 outputs the audio signal whose volume has been changed to the D / A converter unit 15 for each channel.

  The D / A converter unit 15 includes a plurality of D / A converters. Each level adjuster provided in the level adjustment unit 20 is connected to each D / A converter provided in the D / A converter unit 15. The D / A converter unit 15 receives an audio signal whose volume has been changed from the level adjustment unit 20 for each channel. The D / A converter 15 converts the input audio signal from a digital signal to an analog signal for each channel. The amplifier unit 16 amplifies the audio signal of each channel input from the D / A converter unit 15 for each channel. Each speaker included in the output unit 17 outputs the audio signal of each channel amplified by the amplifier unit 16 as sound.

  Here, the types of multi-channels, the channel configuration of each multi-channel, specific channels, and channels other than the specific channels are shown in Table 1.

  As shown in the above (Table 1), the multi-channel includes, for example, 3ch, 4ch, 5.1ch, 6.1ch, 7.1ch. In the above (Table 1), “L” means a front left channel (hereinafter referred to as L channel). “R” means a front light channel (hereinafter referred to as “R channel”). “S” means a surround channel (hereinafter referred to as “S channel”). “Ls” is a left surround channel (hereinafter referred to as Ls channel). “Rs” means a write surround channel (hereinafter referred to as Rs channel). “C” is a center channel (hereinafter referred to as C channel). “LFE” means a subwoofer (hereinafter referred to as an LFE channel). “BS” means a back surround channel (hereinafter referred to as a BS channel). “Lb” means a write-back channel (hereinafter referred to as Lb channel). “Rb” means a write-back channel (hereinafter referred to as Rb channel).

  When the multi-channel is 3ch, the specific channel includes an L channel and an R channel. On the other hand, channels other than the specific channel are composed of S channels.

  When the multi-channel is 4ch, the specific channel is composed of an L channel and an R channel. On the other hand, channels other than the specific channel are configured by an Ls channel and an Rs channel.

  When the multi-channel is 5.1ch, the specific channel includes an L channel, an R channel, and a C channel. On the other hand, channels other than the specific channel include an Ls channel, an Rs channel, and an LFE channel.

  When the multi-channel is 6.1ch, the specific channel includes an L channel, an R channel, and a C channel. On the other hand, channels other than the specific channel include an Ls channel, an Rs channel, a Bs channel, and an LFE channel.

  When the multi-channel is 7.1ch, the specific channel is composed of an L channel, an R channel, and a C channel. On the other hand, channels other than the specific channel include an Ls channel, an Rs channel, an Lb channel, an Rb channel, and an LFE channel.

  Since the automatic sound quality control apparatus according to the first embodiment of the present invention changes the frequency characteristic only for the audio signal of the specific channel, the equalizer may be removed from the configuration for the audio signal of the channel other than the specific channel. it can. For this reason, it is possible to reduce the amount of calculation and make the hardware cheaper than the conventional automatic sound quality control device that changes the frequency characteristics of the audio signals of all channels. In addition, channels other than the specific channel often include sound effects with a low level mainly to increase the sense of presence. Therefore, by changing the frequency characteristics for the audio signal of a specific channel and increasing the level by the volume component that is the average value of the compensation amount for the audio signal of a channel other than the specific channel, the masking due to noise is compensated for hearing. Thus, it is possible to provide an automatic sound quality control device that does not significantly impair the effect. According to the automatic sound quality control apparatus of the first embodiment of the present invention, it is possible to automatically reproduce a multi-channel audio signal in an environment where there is noise such as in a vehicle.

  The first A / D converter unit 11 may be included in the input unit 10 or may be included in the DSP 14. Further, the second A / D converter unit 13 may be included in the microphone 12 or may be included in the DSP 14. The D / A converter unit 15 may be included in the DSP 14 or may be included in the amplifier unit 16 or the output unit 17. The amplifier unit 16 may be included in the output unit 17. The automatic control device 1 does not necessarily include the microphone 12 and may have any configuration as long as a noise signal that is a digital signal is input to the DSP 14.

  In addition, although DSP14 illustrated having an adder, a multiplier, and an accumulator, you may be comprised with other hardware and those combination. Each functional block such as the calculation unit 18 included in the DSP 14 is typically realized as an LSI (Large Scale Integration) which is an integrated circuit. These may be individually made into one chip, or may be made into chips so as to include a part or all of them. Although referred to as LSI here, it may be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used. Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. There is a possibility of adaptation of biotechnology.

(Other aspects of the first embodiment)
As another aspect of the first embodiment of the present invention, the automatic sound quality control device 1 may be configured as shown in FIG. Another aspect of the first embodiment of the present invention is different from the first embodiment of the present invention in the arrangement of the equalizer unit 29 and the level adjusting unit 30 included in the DSP 14. Other configurations of other aspects of the first embodiment of the present invention are the same as those of the first embodiment of the present invention.

  The level adjustment unit 30 includes a plurality of level adjusters. Each level adjuster provided in the level adjustment unit 30 is connected to each A / D converter provided in the first A / D converter unit 11. The level adjustment unit 30 receives an audio signal for each channel from the first A / D converter unit 11. Further, the calculation unit 18 is connected to each level adjuster provided in the level adjustment unit 30. The level adjustment unit 30 receives the volume component ν from the calculation unit 18. The level adjustment unit 30 changes the volume by adding the volume component ν input from the calculation unit 18 to the audio signal of each channel input from the first A / D converter unit 11. The level adjustment unit 30 is connected to the equalizer unit 29. The level adjustment unit 30 outputs the audio signal of the specific channel to the equalizer unit 29 for each channel. The level adjustment unit 30 is connected to the D / A converter unit 15. The level adjustment unit 30 outputs audio signals of channels other than the specific channel to the D / A converter unit 15 for each channel.

  The equalizer unit 29 includes a plurality of equalizers. Each level adjuster provided in the level adjustment unit 30 is connected to each equalizer provided in the equalizer unit 29. An audio signal of a specific channel is input to the equalizer unit 29 from the level adjustment unit 30 for each channel. Further, the calculation unit 18 is connected to each equalizer included in the equalizer unit 29. The frequency component C ′ (i) is input from the calculation unit 18 to the equalizer unit 29. The equalizer unit 29 divides the audio signal of the specific channel input from the level adjustment unit 30 into the same frequency band as the frequency band included in each division i used in the calculation unit 18. The equalizer unit 29 increases the level of each frequency component C ′ (i) with respect to the signal of the portion corresponding to each section i (1 ≦ i ≦ N) in the input audio signal of the specific channel. Thereby, the equalizer unit 29 changes the frequency characteristic of the audio signal of the input specific channel. The equalizer unit 29 is connected to the D / A converter unit 15. The equalizer unit 29 outputs the audio signal of the specific channel whose frequency characteristic is changed to the D / A converter unit 15 for each channel.

  Each D / A converter included in the D / A converter unit 15 is connected to each equalizer included in the equalizer unit 29 and each level adjuster included in the level adjustment unit 30. The D / A converter unit 15 converts the audio signal of each channel input from the equalizer unit 29 and the level adjustment unit 30 from a digital signal to an analog signal. The amplifier unit 16 amplifies the audio signal of each channel input from the D / A converter unit 15. The output unit 17 outputs the audio signal of each channel amplified by the amplifier unit 16 as sound.

(Second Embodiment)
FIG. 3 is a block diagram showing the configuration of the automatic sound quality control device 1 according to the second embodiment of the present invention. In FIG. 3, in the automatic sound quality control apparatus 1 according to the second embodiment of the present invention, the DSP 34 includes a calculation unit 38, a first equalizer unit 39 a, a second equalizer unit 39 b, and a level adjustment unit 40. This is different from the configuration of the first embodiment. Since other configurations are the same as those of the first embodiment, detailed description of corresponding portions is omitted. Hereinafter, how the audio signal is compensated through the DSP 34 will be described.

The calculation unit 38 is based on the audio signal input for each channel from the first A / D converter unit 11 and the noise signal input for each channel from the second A / D converter unit 13. A compensation amount, a frequency component, and a volume component are calculated. The calculation unit 38 adds and synthesizes the input audio signals of the respective channels, and divides the added and synthesized audio signal into predetermined frequency bands. The total number of sections is two types, N ₁ and N ₂ . N ₁ and N ₂ are integers greater than ₁ , and N ₂ <N ₁ . The frequency band section i can take an integer value of ₁ or more and N ₁ or less. The frequency band section j can take an integer value of 1 or more and N ₂ or less. Here, in order to simplify the description, an example in which N ₁ is a multiple of N ₂ is shown.

First, the calculation unit 38 is based on the audio signal input and synthesized for each channel from the first A / D converter unit 11 and the noise signal input from the second A / D converter unit 13. Thus, the first frequency component C ′ ₁ (i) (1 ≦ i ≦ N ₁ ) and the volume component ν when the number of frequency band sections is N ₁ are calculated in the same manner as in the first embodiment.

Next, the calculation unit 38 calculates the second frequency based on the first frequency component C ′ ₁ (i) (1 ≦ i ≦ N ₁ ) calculated for each section i and the following (Equation 2). The component C ′ ₂ (j) (1 ≦ j ≦ N ₂ ) is calculated.

The calculation unit 38 is connected to the first equalizer unit 39a. The calculation unit 38 outputs the first frequency component C ′ ₁ (i) (1 ≦ i ≦ N ₁ ) calculated for each section i to the first equalizer unit 39a. The calculation unit 38 is connected to the second equalizer unit 39b. The calculation unit 38 outputs the second frequency component C ′ ₂ (j) (1 ≦ j ≦ N ₂ ) calculated for each section j to the second equalizer unit 39b. The calculation unit 38 is connected to the level adjustment unit 40. The calculation unit 38 outputs the volume component ν to the level adjustment unit 40.

The first equalizer unit 39a includes a plurality of equalizers. Each equalizer provided in the first equalizer unit 39a is connected to each A / D converter to which an audio signal of a specific channel is input among the plurality of A / D converters provided in the first A / D converter unit 11. The An audio signal of a specific channel is input from the first A / D converter unit 11 to the first equalizer unit 39a for each channel. Moreover, the calculation part 38 is each connected to each equalizer with which the 1st equalizer part 39a is provided. The first frequency component C ′ ₁ (i) (1 ≦ i ≦ N ₁ ) is input from the calculation unit 38 to the first equalizer unit 39a. The first equalizer unit 39a classifies the audio signal of the specific channel input from the first A / D converter unit 11 for each frequency band that is the same as the frequency band included in each class i used in the calculation unit 38. To do. The first equalizer unit 39a applies each first frequency component C ′ ₁ (i) to the signal corresponding to each section i (1 ≦ i ≦ N ₁ ) of the input audio signal of the specific channel. Just raise the level. Thereby, the first equalizer unit 39a changes the frequency characteristic of the audio signal of the input specific channel. The first equalizer unit 39 a is connected to the level adjustment unit 40. The first equalizer unit 39a outputs the audio signal of the specific channel whose frequency characteristic is changed to the level adjusting unit 40 for each channel.

The second equalizer unit 39b includes at least one equalizer. Each of the equalizers included in the second equalizer unit 39b includes an A / D converter to which an audio signal of a channel other than the specific channel among the plurality of A / D converters included in the first A / D converter unit 11 is input. Is connected. Audio signals of channels other than the specific channel are input from the first A / D converter unit 11 to the second equalizer unit 39b for each channel. Moreover, the calculation part 38 is each connected to each equalizer with which the 2nd equalizer part 39b is provided. Each second frequency component C ′ ₂ (j) (1 ≦ j ≦ N ₂ ) is input from the calculation unit 38 to the second equalizer unit 39b. The second equalizer unit 39 b uses the same frequency band as the frequency band included in each section j used in the calculation unit 38 for the audio signals of channels other than the specific channel input from the first A / D converter unit 11. Divide by each. The second equalizer unit 39b applies each second frequency component C ′ ₂ to the signal corresponding to each section j (1 ≦ j ≦ N ₂ ) of the input audio signals of channels other than the specific channel. Raise the level by (j). Thereby, the second equalizer unit 39b changes the frequency characteristic of the audio signal of the channel other than the input specific channel. The second equalizer unit 39 b is connected to the level adjustment unit 40. The second equalizer unit 39b outputs audio signals of channels other than the specific channel whose frequency characteristics are changed to the level adjusting unit 40 for each channel.

  The level adjustment unit 40 includes a plurality of level adjusters. Each level adjuster provided in the level adjustment unit 40 is connected to each equalizer provided in the first equalizer unit 39a and each equalizer provided in the second equalizer unit 39b. An audio signal of a specific channel whose frequency characteristic is changed is input to the level adjustment unit 40 for each channel from the first equalizer unit 39a. Further, the audio signal of the channel other than the specific channel whose frequency characteristic is changed is input to the level adjusting unit 40 for each channel from the second equalizer unit 39b. A calculation unit 38 is connected to each level adjuster included in the level adjustment unit 40. The level adjustment unit 40 receives the volume component ν from the calculation unit 38. The level adjustment unit 40 changes the volume by adding the volume component ν input from the calculation unit 38 to the audio signals of the respective channels input from the first equalizer unit 39a and the second equalizer unit 39b. The level adjustment unit 40 is connected to the D / A converter unit 15. The level adjustment unit 40 outputs the audio signal of each channel whose volume has been changed to the D / A converter unit 15 for each channel.

  The D / A converter unit 15 converts the audio signal of each channel input from the level adjustment unit 40 from a digital signal to an analog signal. The amplifier unit 16 amplifies the audio signal of each channel input from the D / A converter unit 15. The output unit 17 outputs the audio signal of each channel amplified by the amplifier unit 16 as sound.

  In the automatic sound quality control device 1 according to the second embodiment, two equalizers are used. However, three or more equalizers may be used.

  According to the automatic sound quality control apparatus of the second embodiment of the present invention as described above, the number of frequency band sections for audio signals of channels other than the specific channel is equal to the number of frequency band sections for audio signals of the specific channel. Smaller than. For this reason, although the amount of calculation increases compared with the automatic sound quality control apparatus of the first embodiment that changes only the volume of audio signals other than the specific channel, conventional automatic sound quality control that changes the frequency characteristics of the audio signals of all channels. It is possible to provide an automatic sound quality control device in which the calculation amount is reduced as compared with the device and the hardware is configured at a low cost. In addition, the number of frequency band divisions for audio signals of channels other than the specific channel is smaller than the number of frequency band divisions for audio signals of the specific channel. For this reason, an automatic sound quality control device that does not impair the effect of compensating for masking due to noise can be provided in terms of audibility compared to the first embodiment. According to this automatic sound quality control device, it is possible to automatically reproduce a multi-channel audio signal in an environment where there is noisy noise such as in a vehicle.

(Other aspects of the second embodiment)
As another aspect of the second embodiment of the present invention, the automatic sound quality control device 1 may be configured as shown in FIG. Another aspect of the second embodiment of the present invention is different from the second embodiment of the present invention in the arrangement of the first equalizer unit 49a, the second equalizer unit 49b, and the level adjusting unit 50. Other configurations of other aspects of the second embodiment of the present invention are the same as those of the second embodiment of the present invention.

  The level adjustment unit 50 includes a plurality of level adjusters. Each level adjuster provided in the level adjustment unit 50 is connected to each A / D converter provided in the first A / D converter unit 11. An audio signal is input to the level adjustment unit 50 from the first A / D converter unit 11 for each channel. Further, a calculation unit 38 is connected to each level adjuster included in the level adjustment unit 50. The level adjustment unit 50 receives the volume component ν from the calculation unit 38. The level adjustment unit 50 adds the volume component ν input from the calculation unit 38 to the audio signal of each channel input from the first A / D converter unit 11 to change the volume. The level adjusting unit 50 is connected to the first equalizer unit 49a and the second equalizer unit 49b. The level adjustment unit 50 outputs an audio signal of a specific channel to the first equalizer unit 49a for each channel, and outputs an audio signal of a channel other than the specific channel to the second equalizer unit 49b for each channel.

The first equalizer unit 49a includes a plurality of equalizers. Each equalizer provided in the first equalizer unit 49a is connected to each level adjuster to which an audio signal of a specific channel is input among the plurality of level adjusters provided in the level adjuster 50. An audio signal of a specific channel is input from the level adjustment unit 50 to the first equalizer unit 49a for each channel. Moreover, the calculation part 38 is connected to each equalizer with which the 1st equalizer part 49a is provided. Each first frequency component C ′ ₁ (i) (1 ≦ i ≦ N ₁ ) is input from the calculation unit 38 to the first equalizer unit 49a. The first equalizer unit 49 a divides the audio signal of the specific channel input from the level adjustment unit 50 for each frequency band that is the same as the frequency band included in each division i used in the calculation unit 38. The first equalizer unit 49a applies each first frequency component C ′ ₁ (i) to the signal of the portion corresponding to each section i (1 ≦ i ≦ N ₁ ) in the input audio signal of the specific channel. Raise the level by (1 ≦ i ≦ N ₁ ). Thereby, the first equalizer unit 49a changes the frequency characteristics of the input audio signal of the specific channel. The first equalizer unit 49 a is connected to the D / A converter unit 15. The first equalizer unit 49a outputs the audio signal of the specific channel whose frequency characteristic is changed to the D / A converter unit 15 for each channel.

The second equalizer unit 49b includes at least one equalizer. Each equalizer provided in the second equalizer unit 49b is connected to each level adjuster to which an audio signal of a channel other than the specific channel is input among the plurality of level adjusters provided in the level adjuster 50. Audio signals of channels other than the specific channel are input from the level adjustment unit 50 to the second equalizer unit 49b for each channel. Moreover, the calculation part 38 is connected to each equalizer with which the 2nd equalizer part 49b is provided. Each second frequency component C ′ ₂ (j) (1 ≦ j ≦ N ₂ ) is input from the calculation unit 38 to the second equalizer unit 49b. The second equalizer unit 59b divides the audio signals of channels other than the specific channel input from the level adjustment unit 50 into the same frequency bands as the frequency bands included in each division j used in the calculation unit 38. The second equalizer unit 49b applies each second frequency component C ′ ₂ (j) to the portion of the signal corresponding to each section j (1 ≦ j ≦ N ₂ ) in the input audio signal of the specific channel. Raise the level by (1 ≦ j ≦ N ₂ ). Thereby, the second equalizer unit 49b changes the frequency characteristic of the audio signal of the channel other than the input specific channel. The second equalizer unit 49 b is connected to the D / A converter unit 15. The second equalizer unit 49b outputs audio signals of channels other than the specific channel whose frequency characteristics have been changed to the D / A converter unit 15 for each channel.

  Each D / A converter included in the D / A converter unit 15 is connected to each equalizer included in the first equalizer unit 49a and each equalizer included in the second equalizer unit 49b. The D / A converter unit 15 converts the audio signal of each channel input from the first equalizer unit 49a and the second equalizer unit 49b from a digital signal to an analog signal. The amplifier unit 16 amplifies the audio signal of each channel input from the D / A converter unit 15. The output unit 17 outputs the audio signal of each channel amplified by the amplifier unit 16 as sound.

  As described above, the automatic sound quality control apparatus according to the present invention has an effect of reducing the amount of calculation and compensating for masking of a multi-channel audio signal with an inexpensive hardware configuration, and there is noise in a vehicle. In an environment, a multi-channel audio signal can be automatically reproduced so as to be easily heard, which is useful.

1 is a block diagram of an automatic sound quality control device 1 according to a first embodiment of the present invention. The block diagram of the automatic sound quality control apparatus 1 of the other aspect of the 1st Embodiment of this invention. The block diagram of the automatic sound quality control apparatus 1 of the 2nd Embodiment of this invention. The block diagram of the automatic sound quality control apparatus 1 of the other aspect of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Input part 11 1st A / D converter part 12 Microphone 13 2nd A / D converter part 14, 34 DSP
15 D / A converter section 16 Amplifier section 17 Output section 18, 38 Calculation section 19, 29 Equalizer section 20, 30, 40, 50 Level adjustment section 39a, 49a First equalizer section 39b, 49b Second equalizer section

Claims (6)

A compensation amount that compensates for masking of a multi-channel audio signal by a noise signal is calculated for each frequency band, and a volume component that is an average value of the compensation amount, and a frequency obtained by subtracting the volume component from the compensation amount. A calculation unit for calculating the components;
A frequency characteristic changing unit that changes only a frequency characteristic of an audio signal of a specific channel included in the multi-channel based on the frequency component calculated by the calculating unit;
Based on the volume component calculated by the calculation unit, a volume change unit that changes the volume of the audio signals of all channels included in the multi-channel,
The frequency characteristic is changed by the frequency characteristic changing unit, the audio signal of the specific channel whose volume is changed by the volume changing unit, and the audio signal of a channel other than the specific channel whose volume is changed by the volume changing unit; An automatic sound quality control device including an output unit that outputs sound as sound. A compensation amount that compensates for masking of a multi-channel audio signal by a noise signal is calculated for each frequency band, and a volume component that is an average value of the compensation amount, and a subtracting the volume component from the compensation amount, respectively. And calculating a second frequency component based on the number of frequency band segments, the number of segments less than the number of frequency band segments, and the first frequency component. A calculation unit for calculating a component;
A first frequency characteristic changing unit that changes only a frequency characteristic of an audio signal of a specific channel included in the multi-channel based on the first frequency component calculated by the calculating unit;
Based on the second frequency component calculated by the calculation unit, a second frequency characteristic changing unit that changes only the frequency characteristic of an audio signal of a channel other than the specific channel among the multichannels;
Based on the volume component calculated by the calculation unit, a volume change unit that changes the volume of the audio signals of all channels included in the multi-channel,
The frequency characteristic is changed by the first frequency characteristic changing unit, the audio signal of the specific channel whose volume is changed by the volume changing unit, and the frequency characteristic is changed by the second frequency characteristic changing unit, and the volume An automatic sound quality control apparatus comprising: an output unit that outputs an audio signal of a channel other than the specific channel whose volume has been changed by the changing unit as a sound. When the multi-channel includes a center channel, the specific channels are a front right channel, a front left channel, and a center channel,
The automatic sound quality control device according to claim 1 or 2, wherein when the multi-channel does not include a center channel, the specific channels are a front right channel and a front left channel. A compensation amount that compensates for masking of a multi-channel audio signal by a noise signal is calculated for each frequency band, and a volume component that is an average value of the compensation amount, and a frequency obtained by subtracting the volume component from the compensation amount. A calculation unit for calculating the components;
A frequency characteristic changing unit that changes only a frequency characteristic of an audio signal of a specific channel included in the multi-channel based on the frequency component calculated by the calculating unit;
An integrated circuit comprising: a volume changing unit that changes the volume of audio signals of all channels included in the multi-channel based on the volume component calculated by the calculating unit. A compensation amount that compensates for masking of a multi-channel audio signal by a noise signal is calculated for each frequency band, and a volume component that is an average value of the compensation amount, and a subtracting the volume component from the compensation amount, respectively. And calculating a second frequency component based on the number of frequency band segments, the number of segments less than the number of frequency band segments, and the first frequency component. A calculation unit for calculating a component;
A first frequency characteristic changing unit that changes only a frequency characteristic of an audio signal of a specific channel included in the multi-channel based on the first frequency component calculated by the calculating unit;
Based on the second frequency component calculated by the calculation unit, a second frequency characteristic changing unit that changes only the frequency characteristic of an audio signal of a channel other than the specific channel among the multichannels;
An integrated circuit comprising: a volume changing unit that changes the volume of audio signals of all channels included in the multi-channel based on the volume component calculated by the calculating unit. When the multi-channel includes a center channel, the specific channels are a front right channel, a front left channel, and a center channel,
6. The integrated circuit according to claim 4, wherein when the multi-channel does not include a center channel, the specific channels are a front right channel and a front left channel.

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