JP2008092411A - Audio signal generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio signal generating device which generates stereo signals as expanded stereo signals having a wide interval through narrow-interval speakers, and reproduces a center sound source as a signal giving no feeling of absence of center localization. <P>SOLUTION: The audio signal generating device includes: FFT means 21 and 22 for obtaining sine wave components and cosine wave components at predetermined frequency intervals by Fourier-transforming a stereo signal; a frequency detecting means 24 for comparing the sine wave components and cosine wave components with each other respectively to detect frequencies having level differences within a predetermined range; an adding means 27 for obtaining addition components by adding sine wave components and cosine wave components of the frequencies detected by the frequency detecting means respectively among sine and cosine wave components obtained by the FFT means; an IFFT means 28 for inversely Fourier-transforming the addition components to obtain addition stereo signals; and signal generating means 3 and 4 for adding the addition audio signals to the expanded stereo signals obtained by processing the stereo signals to generate audio signals for reproduction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention generates a stereo signal from a narrow-spaced speaker arranged at a narrower interval than left and right speakers at a predetermined interval, and generates the stereo sound signal as an enlarged stereo signal having a wider interval than the narrow-spaced speaker. The present invention relates to a signal generation device.

Recently, small speakers capable of producing sound signals with high fidelity have come into practical use, and stereo reproduction devices that are small but have excellent realism have come into the market.
On the other hand, in order to perform stereo reproduction with a sense of presence, it is usually assumed that left and right speakers are installed at a position that becomes an equilateral triangle, that is, a position of ± 30 degrees in front of the viewer. In some cases, it is necessary to install a speaker in a narrow space. A predetermined stereo effect is obtained even when the installation angle of the speaker is small.

  In a loudspeaker arrangement with a small installation angle, a desired stereo effect can be obtained by generating sound from the loudspeaker with an enlarged stereo sound that localizes the sound source outside the position where the left and right speakers are arranged. However, in playback with expanded stereo sound, the central sound source located in the center of the left and right speakers is also enlarged and played, so the enlarged central sound source is not localized at the center position of the left and right speakers, and is played back as a so-called hollow sound. Will be. The vocal sound source sung in the center of the speaker is viewed as a sound dispersed around. It is preferable that a desired stereo effect can be obtained even when the installation angle of the left and right speakers is small, and that the sound source localized at the center of the speaker can be reproduced with a sound without any hollows.

Patent Document 1 discloses a sound field reproduction device that eliminates the unnatural feeling at the time of a monaural signal by switching the effect of the stereo enhancement process depending on whether the input signal is stereo or monaural. Whether the input signal is a stereo signal or a monaural signal is determined by a determination circuit, and based on this result, the ratio of the addition of the output signal of the FIR filter and the input signal is changed. When the input signal is stereo, the output signal of the FIR filter is larger, and when the input signal is monaural, the input signal is controlled by controlling the rate of addition in the adder so that the output signal of the FIR filter is smaller. Has disclosed a sound field reproduction device in which the blurring of the sound image and the deterioration of the sound quality are not conspicuous when the sound is monaural.
JP-A-5-243882

  However, the sound field reproducing device disclosed in Patent Document 1 only changes the effect of expanding the stereo feeling depending on whether the input signal is a stereo signal or a signal close to monaural. When the instruments are arranged in stereo and the vocals are singing in the center with a monaural sound with no blur, the accompaniment instruments are enlarged and played with the stereo expansion effect, and the vocals are also played with the expansion effect Therefore, the blur of the sound image of the vocal sound and the deterioration of the sound quality become conspicuous. In particular, when a stereo signal is sounded from a narrowly spaced speaker arranged at a narrower interval than left and right speakers at a predetermined interval, and the stereo signal is generated as an enlarged stereo signal having a wider interval than that of the narrowly spaced speaker, the center position The effect of the enlarged stereo sound signal is also given to the vocal sound source that is localized to the sound source, and it has not been possible to realize a sound signal generation device that generates a sound source for reproduction together with a vocal sound source without blur.

  Accordingly, the present invention has been made to solve the above-described problems. A stereo signal is generated by a narrowly spaced speaker arranged at a narrower interval than left and right speakers having a predetermined interval, and the stereo signal is narrowly spaced. It is generated as an enlarged stereo signal with a wider interval than the speakers, and only the central sound source localized at the center of the left and right speakers does not give the effect of the enlarged stereo sound signal, and as a playback acoustic signal without a sense of hollow It is an object of the present invention to provide an acoustic signal generation device that enables generation.

  According to a first aspect of the present invention, the processing for localizing a sound image to a position expanded to the left and right relative to the sound image localization position obtained when the input audio signals of two left and right channels are reproduced by a pair of left and right speakers is input. In an acoustic signal generating apparatus for outputting an enlarged audio signal obtained by performing an audio signal, a sine wave component of each frequency for each predetermined frequency interval by Fourier transforming each of the input left and right channel audio signals And the FFT means for obtaining the cosine wave component, and the level difference between the sine wave component of the left channel audio signal and the sine wave component of the right channel audio signal for each frequency obtained from the FFT means is compared and the level difference is within a predetermined range. Is detected from the FFT means, and a first frequency group having a single frequency group is detected. The second frequency group in which the levels of the cosine wave component of the left channel audio signal and the cosine wave component of the right channel audio signal for each frequency are compared and the frequencies having a level difference within a predetermined range are grouped together. The frequency group detecting means for detecting, the frequency detecting means for detecting a common frequency among the frequencies of the first frequency group and the frequency of the second frequency group detected by the frequency group detecting means, and the FFT means. Of the sine wave component of the left channel audio signal of each frequency and the sine wave component of the right channel audio signal of each frequency, the sine wave components of the common frequency detected by the frequency detection means are added together to add sine And a cosine wave component of the left channel audio signal of each frequency obtained by the FFT means and the right of each frequency. Among the cosine wave components of the channel audio signal, adding means for adding the cosine wave components of the common frequency detected by the frequency detecting means to obtain an added cosine wave component, and the addition sine obtained from the adding means IFFT means for obtaining an added audio signal by performing inverse Fourier transform on the wave component and the added cosine wave component, and the added audio signal obtained by the IFFT means to the enlarged audio signal subjected to the process of localizing the sound image to the position expanded to the left and right There is provided an acoustic signal generation device comprising: signal generation means for generating a signal obtained by adding signals as a new enlarged audio signal.

  According to the present invention, the FFT means for obtaining the sine wave component and the cosine wave component of each frequency for each predetermined frequency interval by Fourier transforming each of the input left and right two-channel audio signals, and each obtained by the FFT means The levels of the sine wave component of the left channel audio signal and the sine wave component of the right channel audio signal for each frequency are compared to detect a first frequency group in which frequencies having a level difference within a predetermined range are grouped together. , The levels of the cosine wave component of the left channel audio signal and the cosine wave component of the right channel audio signal obtained for each frequency obtained by the FFT means are compared, and the frequencies whose level difference is within a predetermined range are defined as one unit. Frequency group detecting means for detecting two frequency groups, and the frequency of the first frequency group detected by the frequency group detecting means and the second frequency group The frequency detection means for detecting a common frequency among the frequencies of the frequency group, and the frequency of the sine wave component of the left channel audio signal of each frequency and the sine wave component of the right channel audio signal of each frequency obtained by the FFT means The sine wave components of the common frequency detected by the detecting means are added together to obtain an added sine wave component, and the cosine wave component of the left channel audio signal of each frequency and the right channel audio of each frequency obtained by the FFT means. Of the cosine wave components of the signal, an adding means for adding the cosine wave components of the common frequency detected by the frequency detecting means to obtain an added cosine wave component, and an added sine wave component and an added cosine obtained from the adding means IFFT means for obtaining an added audio signal by performing inverse Fourier transform on wave components, and processing for localizing a sound image at a position expanded left and right And a signal generation unit that generates a signal obtained by adding the added audio signal obtained by the IFFT unit to the expanded audio signal performed as a new expanded audio signal, so that the stereo signal is spaced at a narrower interval than the left and right speakers at a predetermined interval. Generates sound from the arranged narrow-speaker speakers and generates a stereo signal as an enlarged stereo signal with a wider interval than the narrow-speaker speaker, and only the central sound source localized at the center of the left and right speakers has the effect of the enlarged stereo sound signal Therefore, it is possible to realize an acoustic signal generation device that can generate a reproduction acoustic signal without a sense of hollowing out.

Hereinafter, an acoustic signal generation device according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram illustrating a configuration example of an acoustic signal generation device according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the sound image localization expansion operation of the acoustic signal generation device according to the embodiment of the present invention. FIG. 3 is a diagram for explaining transoral processing of the acoustic signal generation device according to the embodiment of the present invention. FIG. 4 is a block diagram illustrating a configuration example of the sound image localization expansion processor of the acoustic signal generation device according to the embodiment of the present invention. FIG. 5 is a flowchart illustrating an operation example of the acoustic signal generation device according to the embodiment of the present invention. FIG. 6 is a flowchart illustrating an application operation example of the acoustic signal generation device according to the embodiment of the present invention.

  The acoustic signal generation device generates a stereo signal as an enlarged stereo signal having a wider interval than that of the narrow interval speaker by causing the stereo signal to sound from a narrow interval speaker arranged at a narrower interval than the left and right speakers at a predetermined interval. In addition, only the central sound source localized at the center of the left and right speakers does not give the effect of the enlarged stereo sound signal, and the object is to realize a device that can be generated as a reproduction sound signal without a sense of hollowing out, FFT means for obtaining a sine wave component and a cosine wave component of each frequency for each predetermined frequency interval by Fourier transforming each of the input left and right two-channel audio signals, and left channel audio for each frequency obtained from the FFT means The level difference between the sine wave component of the signal and the sine wave component of the right channel audio signal is compared. A first frequency group having a set of frequencies in a certain range is detected, and a cosine wave component of the left channel audio signal and a cosine wave component of the right channel audio signal for each frequency obtained by the FFT means Frequency group detecting means for detecting a second frequency group in which frequencies having a level difference within a predetermined range are grouped together, and the frequency of the first frequency group detected by the frequency group detecting means, A frequency detection means for detecting a common frequency among the frequencies of the second frequency group; a sine wave component of the left channel audio signal of each frequency and a sine wave component of the right channel audio signal of each frequency obtained by the FFT means; Among them, the sine wave components of the common frequency detected by the frequency detection means are added together to obtain an addition sine wave component, and the FFT means Among the obtained cosine wave components of the left channel audio signal of each frequency and the cosine wave components of the right channel audio signal of each frequency, add and add the cosine wave components of the common frequency detected by the frequency detection means. An adding means for obtaining a cosine wave component, an IFFT means for obtaining an added audio signal by performing inverse Fourier transform on the added sine wave component and the added cosine wave component obtained from the adding means, and a process for localizing the sound image to a position expanded left and right This is realized by including signal generation means for generating a signal obtained by adding the added audio signal obtained by the IFFT means to the performed enlarged audio signal as a new enlarged audio signal.

The configuration of the acoustic signal generation device will be described.
The acoustic signal generation device 10 shown in FIG. 1 includes a stereo sound expansion processing unit 1 including a sound image localization expansion processor 11 and a transoral reproduction processor 12, FFTs (Fast Fourier Transforms) 21, 22, and amplitude. A center sound processing unit 2 including a phase comparator 23, a central component determiner 24, central component extractors 25 and 26, a component adder 27, an IFFT (Inverse fast Fourier transform) 28, and a controller 29. And adders 3 and 4.
The acoustic signal generation apparatus shown in FIG. 4 includes a sound image localization expansion processor 11 including filters 111 and 112, and a transoral reproduction processor 12 including filters 121 and 122, addition circuits 123 and 124, filters 125 and 126. Composed.

The operation of the acoustic signal generator will be described.
First, the left and right sound input signals input to the sound signal generation device 10 are input to the stereo sound expansion processing unit 1 and the center sound processing unit 2. When the sound image localization enlargement processor 11 of the stereo sound enlargement processing unit 1 produces a sound from the playback speakers arranged at narrow intervals, the position of the speaker at which the generated sounds are arranged at normal intervals when the left and right sound input signals are produced from the reproduction speakers. Then, an enlarged acoustic signal is generated by enlarging the sound image localization so that the sound is heard when using headphones as a sound generated from the sound. When the transoral reproduction processor 12 reproduces the enlarged sound signal generated for listening to headphones through a speaker, the viewer generates the reproduced sound from the speaker as a speaker reproduction signal that is viewed in the same manner as when listening to the headphones.

  The center sound processing unit 2 acquires only the sound signal localized at the center from the input left and right sound input signals as the center sound signal. The adder 3 adds the left output signal generated as the speaker reproduction signal by the transoral reproduction processor 12 and the center sound signal acquired by the center sound processing unit 2 and outputs the result. Similarly, the adder 4 adds and outputs the right output signal generated as the speaker reproduction signal and the center sound. The left and right output signals output from the acoustic signal generation device 10 are reproduced as enlarged sound signals generated from the positions of the speakers arranged at normal intervals when the sound emitted from the speakers arranged at narrow intervals is reproduced. The sound source localized in the center by the sound input signal is not subjected to the enlarged sound signal processing, and the sound signal generation device 10 is generated that is generated as a reproduction sound signal without blurring of the center sound source and a feeling of hollowing out.

Next, this will be described in detail.
The center sound processing unit 2 shown in FIG. 1 will be further described.
The FFT 21 performs a high-speed frequency conversion process on the left sound input signal sampled at, for example, 44.1 kHz and converted into a digital signal, for example, using 1024 sampling points as window sections. A sine frequency component and a cosine frequency component of the left acoustic input signal are obtained. The FFT 22 similarly obtains a sine frequency component and a cosine frequency component of the right sound input signal. The amplitude phase comparator 23 compares the sine frequency component and the cosine frequency component of the left and right acoustic input signals output from the FFTs 21 and 22, and compares the level difference between the sine frequency component and the cosine frequency component obtained by comparison. Are output for each frequency obtained by analysis. The central component determination unit 24 compares the sine frequency component of the left acoustic input signal, the cosine frequency component, the sine frequency component of the right acoustic input signal, and the corresponding cosine frequency component for each frequency obtained by analysis. Then, it is determined that the center sound signal is localized at the center of the right and left speakers for viewing, with the frequency value having a level difference of, for example, 3 dB or less between the sine frequency component and the cosine frequency component at the same frequency component.

  The central component extractor 25 acquires each of the sine frequency component and the cosine frequency component determined to be the center sound signal among the frequencies constituting the left sound input signal obtained by frequency analysis by the FFT 21. The central component extractor 26 acquires each of the sine frequency component and the cosine frequency component determined to be the center sound signal among the frequencies constituting the right sound input signal obtained by frequency analysis by the FFT 22. The component adder 27 adds the sine frequency component and the cosine frequency component acquired by the central component extractors 25 and 26, respectively. The IFFT 28 performs inverse fast Fourier transform on each of the sine frequency component and cosine frequency component obtained by the addition in a window period corresponding to the window periods of the FFTs 21 and 22. Only the center sound signal included in the left and right sound input signals is obtained. Each of the adders 3 and 4 adds the extracted center sound signal to the left and right enlarged acoustic signals subjected to the transoral reproduction process.

The acoustic signal generation device 10 outputs a left and right output signal obtained by adding the enlarged left and right enlarged acoustic signals and the center sound signal that has been extracted and not enlarged. Since the center sound signal is output as both a signal that has undergone enlargement processing and a signal that has not undergone enlargement processing, the ambient sound that has undergone enlargement processing and the center sound that has not undergone enlargement processing are viewed as a fused sound. It is a design matter to weaken the center sound signal expansion process, or to adjust the level ratio between the center sound that has been expanded and the center sound that has not been expanded. Therefore, an appropriate distribution ratio is set so that the center sound can be viewed without being separated.
The controller 29 controls each circuit block described above.

  Here, it has been described that the center sound source is extracted by the FFTs 21 and 22 using the sine frequency component and the cosine frequency component, respectively. The center sound source is extracted by the FFTs 21 and 22 by checking the level of the frequency component and the phase difference of the frequency component. For example, when the level difference is about 3 dB and the phase difference is within 30 degrees, for example, the center sound source is extracted. You may do it.

The processing in the sound image localization enlargement processor 11 and the transoral reproduction processor 12 will be further described.
FIG. 2 shows, for example, sound fields generated from left and right speakers 51 and 52 arranged at an opening angle of 20 degrees on the front of the viewer 59, and virtual speakers 53 and 54 arranged at a standard opening angle of 60 degrees. This shows the expansion of the sound image localization for viewing as a sound generated from the sound. That is, the sound generated from the speakers 51 and 52 is heard by the viewer 59 as the sound generated from the virtual speakers 53 and 54. In this case, the transfer function of the sound that is generated from the left virtual speaker 53 and reaches the left ear of the viewer 59 is h _ll , and the transfer function of the sound that reaches the right ear is h _lr . The transfer function of the sound that is generated from the right virtual speaker 54 and reaches the right ear of the viewer 59 is h _rr , and the transfer function of the sound that reaches the left ear is h _rl . When signals reproduced from the left and right virtual speakers 53 and 54 are x _l (t) and x _r (t), the signals f _l (t) and f _r (t) reaching the left and right ears are expressed by the following equations. It is.

Referring to FIG. 3, transoral signal processing for causing sound from left and right speakers 55 and 56 to reach signals f ₁ (t) and f _r (t) of Expression (1) to the left and right ears of viewer 58. Is described.
This figure is a diagram for explaining the transoral reproduction process. The sounds of P _l (t) and P _r (t) collected at the right and left ears of the artificial head 57 at the recording site are shown to the viewer. The signal processing generated in the left and right ears 58 is described.
First, the signals P _l (t) and P _r (t) collected by the left and right ears of the artificial head 57 are input to the trans-oral reproduction processor 12 installed at the reproduction site. The signals output from the transoral reproduction processor are l (t) and r (t), and the signals l (t) and r (t) are generated from the left and right speakers 55 and 56, respectively.

Here, the transfer functions from the speaker 55 to the left and right ears of the viewer 58 are h _LS (t) and h _LO (t), and the transfer functions from the speaker 56 to the right and left ears of the viewer 58 are h _RS (t). , H _RO (t), and the sounds that should reach the left and right ears of the viewer 58 are P ₁ (t) and P _r (t), and are expressed by the following equations.

When both sides of Expression (2) are Fourier transformed and expressed in the form of a matrix, Expression (3) is obtained.

Here, when the filter matrix of the system is F, Equation (3) is expressed by the following equation.

In Expression (4), F is an inverse matrix of the four transfer function determinants H in Expression (3). The transoral system constituted by F is called a feedback system.
The matrix H can be further transformed as follows: Hereinafter, description will be made with (t) omitted.

Equation (5) into equation (3), Dividing both sides by H _LS H _RS.

Equation (6) is inverse Fourier transformed and transposed.

With reference to FIG. 4, the characteristics of the filter processing performed by the sound image localization enlargement processor 11 and the transoral reproduction processor 12 will be described.
The sound image localization enlargement processor 11 is a circuit block that performs the processing shown in Expression (1), and the filter 111 _applies a characteristic of h _ll (t) + h _rl (t) to the input left signal x _l (t). The filter 112 gives a characteristic of h _lr (t) + h _rr (t) to the input right signal x _r (t).
The transoral reproduction processor 12 is a circuit block that performs the processing shown in Expression (7). That is, it is an attempt to view f _l (t) outputted from the sound image localization enlargement processor 11, f _r a (t) as it is to the viewer 58.
Signal processing is performed so that f _l (t) = P _l (t) and f _r (t) = P _r (t).
The characteristic shown in the equation (7) can be obtained by the filters 121, 122, 125, 126 and the addition circuits (subtraction circuits) 123 and 124 shown in the transoral regeneration processor 12.

  The sound image localization enlargement processor 11 and the transoral reproduction processor 12 use a reproduction speaker arranged at a narrow interval, and listen to the reproduced sound as a sound generated from the position of the speaker arranged at a normal interval. As described above, although the sound image localization can be viewed and enlarged, the center sound source localized at the center of the left and right speakers is also viewed with the enlarged acoustic signal processing. The center sound processing unit 2 extracts the center sound source from the left and right sound input signals and reproduces it without performing the enlarged sound signal processing, so that the sound image of the center sound source becomes larger than necessary or is viewed as a hollow sound. It is preventing.

With reference to FIG. 5, the process flow of the acoustic signal generation device 10 will be described.
First, in S (step) 71, the left and right sound input signals are input to the sound signal generation device 10. In S72, the left and right sound input signals are supplied to the stereo sound expansion processing unit 1 and the center sound processing unit 2. In S73, the stereo sound enlargement processing unit 1 performs sound image localization enlargement processing and transoral reproduction processing of the left and right sound input signals, and generates an enlarged sound signal. In S74, the center sound processing unit 2 performs FFT processing on the left and right sound input signals to obtain amplitude and phase information, or component information of sine wave components and cosine wave components. In S75, the component information obtained by the FFT processing is the same between the left and right acoustic input signals, that is, whether it is the center sound signal or not, compared with the acoustic signal reproduced from the vicinity of the left and right speakers. Is determined. In S76, if frequency and level components similar to the left and right are detected, it is determined that the signal is a center sound signal. The center sound component is extracted. In S77, the extracted center component is IFFT to obtain a center sound signal.
In S78, the input signal expanded in S73 and the center sound signal extracted in S77 are added. The acoustic signal obtained by the addition in S79 is output from the acoustic signal generation device 10 as an output signal.

With reference to FIG. 6, the flow of application processing of the acoustic signal generation device 10 will be described.
The application process shown in FIG. 6 differs from the process shown in FIG. 5 in the processing method for extracting the center sound signal from the input signal. The same processes as those shown in FIG. 5 are denoted by the same reference numerals and description thereof is omitted.
In S81, a filter characteristic for passing only the central component is obtained from the frequency characteristic in which the central component of the left and right acoustic signals obtained by the determination in S75 is present. In S82, a filter having the obtained bandpass characteristic is realized. The filter is also similar to an equalizer characteristic having a steep passage and cutoff characteristic. In S83, the center sound signal is extracted by passing the input signal supplied in S72 with the characteristics realized in S82. After S78, the operation is the same, and an acoustic signal is output from the acoustic signal generation device 10.

  As described above, according to the acoustic signal generation device 10 shown in the present embodiment, the left and right two-channel audio signals that are input are Fourier-transformed and the sine wave component and cosine wave of each frequency for each predetermined frequency interval. Compare the levels of the FFT means 21 and 22 for obtaining the components and the sine wave component of the left channel audio signal and the sine wave component of the right channel audio signal for each frequency obtained by the FFT means, and the level difference is within a predetermined range. Detects the first frequency group with a certain frequency as one unit, and compares the level of the cosine wave component of the left channel audio signal and the cosine wave component of the right channel audio signal for each frequency obtained from the FFT means Frequency group detecting means 23 for detecting a second frequency group in which frequencies having a level difference within a predetermined range are grouped, and a frequency A frequency detection means 24 for detecting a common frequency among the frequencies of the first frequency group and the second frequency group detected by the group detection means; and the left channel audio signal of each frequency obtained by the FFT means. Of the sine wave component and the sine wave component of the right channel audio signal of each frequency, the sine wave components of the common frequency detected by the frequency detecting means are added together to obtain an added sine wave component and obtained by the FFT means. Among the cosine wave component of the left channel audio signal of each frequency and the cosine wave component of the right channel audio signal of each frequency, the cosine wave components of the common frequency detected by the frequency detecting means are added together to add the cosine wave component The addition means 27 for obtaining the sum and the addition sine wave component and the addition cosine wave component obtained by the addition means are subjected to inverse Fourier transform to obtain an addition audio IFFT means 28 for obtaining a signal, and signal generation for generating a signal obtained by adding the added audio signal obtained by the IFFT means to the enlarged audio signal subjected to the process of localizing the sound image at a position enlarged left and right as a new enlarged audio signal Since the means 3 and 4 are provided, the stereo signal is emitted from a narrow-spaced speaker arranged at a narrower interval than the left and right speakers at a predetermined interval, and the stereo signal is expanded as a widened stereo signal having a wider interval than the narrow-spaced speaker. Realizes an acoustic signal generation device that can be generated as a reproduction acoustic signal without the effect of an enlarged stereo sound signal, and only the central sound source localized at the center of the left and right speakers does not give the effect of an enlarged stereo sound signal it can.

It is a block diagram which shows the structural example of the acoustic signal generation apparatus which concerns on implementation of this invention. It is a figure for demonstrating the operation | movement of sound image localization expansion of the acoustic signal generation apparatus which concerns on implementation of this invention. It is a figure for demonstrating the trans-oral process of the acoustic signal generator based on implementation of this invention. It is a block diagram which shows the structural example of the sound image localization expansion processor of the acoustic signal generator which concerns on implementation of this invention. It is the figure which showed the operation example of the acoustic signal generation apparatus which concerns on implementation of this invention with the flowchart. It is the figure which showed the example of application operation | movement of the acoustic signal generator based on implementation of this invention with the flowchart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stereo sound expansion process part 2 Center sound process part 3, 4 Adder 10 Acoustic signal production | generation apparatus 11 Sound image localization expansion processer 12 Trans-oral reproduction | regeneration processor 21, 22 FFT
23 Amplitude / phase comparator 24 Central component determination unit 25, 26 Central component extractor 27 Component adder 28 IFFT
29 Controller 111, 112, 121, 122, 125, 126 Filter 123, 124 Adder circuit

Claims (1)

Obtained by performing sound image localization processing on the input audio signal to a position expanded to the left and right with respect to the sound image localization position obtained when the input left and right two-channel audio signals are reproduced by a pair of left and right speakers. In an acoustic signal generation device that outputs an enlarged audio signal,
FFT means for obtaining a sine wave component and a cosine wave component of each frequency for each predetermined frequency interval by Fourier transforming each of the input left and right two-channel audio signals;
The levels of the sine wave component of the left channel audio signal and the sine wave component of the right channel audio signal obtained for each frequency obtained from the FFT means are compared, and the frequencies having a level difference within a predetermined range are defined as one unit. 1 frequency group is detected, and the levels of the cosine wave component of the left channel audio signal and the cosine wave component of the right channel audio signal for each frequency obtained from the FFT means are compared, and the level difference is within a predetermined range. A frequency group detection means for detecting a second frequency group in which a certain frequency is a unit;
Frequency detection means for detecting a common frequency among the frequencies of the first frequency group and the second frequency group detected by the frequency group detection means;
Of the sine wave component of the left channel audio signal of each frequency and the sine wave component of the right channel audio signal of each frequency obtained by the FFT unit, sine wave components of the common frequency detected by the frequency detection unit are combined. Addition to obtain an addition sine wave component, and the frequency detection means detects the cosine wave component of the left channel audio signal of each frequency and the cosine wave component of the right channel audio signal of each frequency obtained by the FFT means. Adding means for adding the cosine wave components having the same common frequency to obtain an added cosine wave component;
IFFT means for obtaining an added audio signal by performing inverse Fourier transform on the added sine wave component and the added cosine wave component obtained from the adding means;
Signal generating means for generating, as a new enlarged audio signal, a signal obtained by adding the added audio signal obtained by the IFFT means to the enlarged audio signal subjected to the process of localizing the sound image at the position expanded to the left and right;
An acoustic signal generation device comprising:

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