JP5454157B2 - Sound processor - Google Patents

Description

  The present invention is a component in which a sound image is localized at a target position (direction) in a stereo format acoustic signal (for example, a component included in each signal of a right channel and a left channel. Hereinafter, referred to as a “localization component”). It relates to technology that emphasizes or suppresses.

  Conventionally, a technique for suppressing a predetermined localization component from an acoustic signal recorded on a recording medium such as a CD has been proposed. For example, Patent Document 1 discloses a technique for suppressing a component (typically a singing sound) in which a sound image is localized in the center direction by subtracting one of stereo audio signals from the other (reverse phase addition). ing.

JP 2007-079413 A

  However, the technique of Patent Document 1 has a problem that the acoustic signal after suppression of a predetermined component is in a monaural format. Similar problems can occur when emphasizing the localization component. In view of the above circumstances, an object of the present invention is to generate a stereo-type acoustic signal in which a localization component is emphasized or suppressed.

  In order to solve the above-described problems, the sound processing apparatus according to the present invention is configured to emphasize or suppress a localization component at a specific position in the stereo first sound signal and the second sound signal, which is configured with coefficient values for each frequency. A first generating means for generating one numerical sequence, and a second numerical sequence composed of coefficient values corresponding to the phase difference for each frequency between the first acoustic signal and the second acoustic signal, and the amplitude of the first acoustic signal, Second generation means for generating from the amplitude of the second acoustic signal and the amplitude of the sum component of both, and a first processing coefficient sequence that is composed of coefficient values for each frequency and emphasizes or suppresses the localization component as a first numerical value sequence Synthesizing means generated from the second numerical sequence, and signal processing means for causing each coefficient value of the first processing coefficient sequence to act on each frequency component of the first acoustic signal and the second acoustic signal. In the above configuration, since the first processing coefficient sequence is applied to each frequency component of the first acoustic signal and the second acoustic signal, it is possible to generate a stereo format acoustic signal in which the localization component is emphasized or suppressed. Is possible. In addition, since the phase difference between the first acoustic signal and the second acoustic signal is reflected in the first processing coefficient sequence, localization is possible even when there is a significant phase difference between the first acoustic signal and the second acoustic signal. There is an advantage that the effect of emphasis or suppression of components can be sufficiently maintained.

  In a preferred aspect of the present invention, the second generation means includes an amplitude calculation means for calculating, for each frequency, an amplitude sum obtained by adding the amplitudes of the first acoustic signal and the second acoustic signal, and an amplitude of the sum component. Setting means for setting each coefficient value of the second numerical sequence according to the difference between the sum and the amplitude of the sum component. In the above aspect, the tendency that the difference between the sum of the amplitudes of the first acoustic signal and the second acoustic signal and the amplitude of the sum component changes according to the phase difference between the first acoustic signal and the second acoustic signal is utilized. Thus, it is possible to generate the second numerical sequence that reflects the phase difference between the first acoustic signal and the second acoustic signal with high accuracy.

  The sound processing apparatus according to a preferred aspect of the present invention includes a sum component generating means for generating a sum component by adding the first sound signal and the second sound signal, and a difference component obtained by suppressing the localization component as the first sound signal. Difference component generating means generated by subtraction with the second acoustic signal, the first generating means generates a first numerical sequence from the sum component and the difference component, and the second generating means generates the sum component. The amplitude of the sum component generated by the means is applied to the generation of the second numerical sequence. In the above aspect, since the sum component used for generating the first numerical sequence is also used for generating the second numerical sequence, there is an advantage that the load of generating the second numerical sequence is reduced.

  In a preferred aspect of the present invention, the first generation means generates a first numerical sequence according to a result of subtracting the other spectrum from one spectrum of the sum component and the difference component. In the above aspect, a spectrum in which the localization component is emphasized or suppressed with high accuracy is generated by subtracting the other spectrum from one spectrum of the sum component and difference component, so that the localization component is effectively emphasized or suppressed. There is an advantage that the obtained first processing coefficient sequence can be generated.

  The sound processing apparatus according to a preferred example of the aspect including the difference component generation unit includes a variable setting unit that variably sets a localization variable indicating the specific position, and the difference component generation unit includes the localization variable set by the variable setting unit. The other is subtracted from one of the first acoustic signal and the second acoustic signal at a ratio according to. In the above aspect, the ratio of the first acoustic signal and the second acoustic signal at the time of subtraction by the difference component generation means is variably set according to the localization variable. Therefore, there is an advantage that the position (direction) of the localization component to be emphasized or suppressed can be variably controlled (not limited to the central direction).

  The acoustic processing device according to a preferred aspect of the present invention subtracts each coefficient value of the first processing coefficient sequence corresponding to one of the localization component enhancement and suppression from a predetermined value to the other of the localization component enhancement and suppression. Third generation means for generating a corresponding second processing coefficient sequence is provided. In the above aspect, it is possible to generate both processing coefficient sequences for emphasizing and suppressing localization components. In addition, since the second processing coefficient sequence is generated by subtracting each coefficient value of the first processing coefficient sequence from the predetermined value, each of the first processing coefficient sequence and the second processing coefficient sequence is generated individually. In comparison, there is an advantage that the load of generating the first processing coefficient sequence and the second processing coefficient sequence is reduced.

  The acoustic processing device according to each of the above aspects is realized by hardware (electronic circuit) such as a DSP (Digital Signal Processor) dedicated to processing of an acoustic signal, or a general-purpose calculation such as a CPU (Central Processing Unit). It is also realized by cooperation between the processing device and a program (software). The program of the present invention includes a first generation process that generates a first numerical sequence that is composed of coefficient values for each frequency and emphasizes or suppresses a localization component at a specific position in the first acoustic signal and the second acoustic signal in stereo format. The second numerical sequence composed of coefficient values corresponding to the phase difference for each frequency between the first acoustic signal and the second acoustic signal is represented by the sum component of the amplitude of the first acoustic signal and the amplitude of the second acoustic signal. A second generation process generated from the amplitude of the first, a synthesis process for generating a first processing coefficient sequence composed of coefficient values for each frequency and emphasizing or suppressing a localization component from the first numerical value sequence and the second numerical value sequence; And causing the computer to execute signal processing in which each coefficient value of the first processing coefficient sequence is applied to each frequency component of the first acoustic signal and the second acoustic signal. According to the above program, the same operation and effect as the sound processing apparatus of the present invention are realized. The program of the present invention is provided to a user in a form stored in a computer-readable recording medium and installed in the computer, or provided from a server device in a form of distribution via a communication network and installed in the computer. Is done.

1 is a block diagram of a sound processing apparatus according to a first embodiment. It is a block diagram of a coefficient setting part. It is a schematic diagram which shows the relationship of each frequency component. It is a block diagram of the 2nd generating part. It is a schematic diagram which shows the relationship of each frequency component. It is a block diagram of the 3rd generating part in a modification. It is a schematic diagram which shows the relationship between a localization variable and coefficient value CA [k]. It is a schematic diagram which shows the relationship between a localization variable and coefficient value CD [k]. It is a schematic diagram which shows the relationship between a localization variable and a phase difference.

<A: First Embodiment>
FIG. 1 is a block diagram of a sound processing apparatus 100 according to the first embodiment of the present invention. A signal supply device 12, a sound emission device 14, and an input device 16 are connected to the sound processing device 100. The signal supply device 12 supplies the sound processing device 100 with time-domain sound signals SIN (SIN_L, SIN_R) representing the waveform of sound (speech and music). The sound signal SIN_L of the left channel and the sound signal SIN_R of the right channel are localized at positions where the sound images of a plurality of sound sources generating sound are different (that is, the sound amplitude and phase differ depending on the position of each sound source). In this way, a stereo signal is collected or processed. A sound collection device (stereo microphone) that collects ambient sound to generate an acoustic signal SIN, a playback device that acquires the acoustic signal SIN from a portable or built-in recording medium, and outputs it to the acoustic processing device 100; A communication device that receives the acoustic signal SIN from the communication network and outputs the acoustic signal SIN to the acoustic processing device 100 may be employed as the signal supply device 12.

  The acoustic processing device 100 generates an acoustic signal SOUT (SOUT_L, SOUT_R) from the acoustic signal SIN supplied by the signal supply device 12. The left-channel acoustic signal SOUT_L and the right-channel acoustic signal SOUT_R are stereo signals in which a localization component in which a sound image is localized at a target position is emphasized or suppressed among the sounds represented by the acoustic signal SIN. The sound emitting device 14 (for example, a stereo speaker or a stereo headphone) emits a sound wave corresponding to the acoustic signal SOUT (SOUT_L, SOUT_R) generated by the acoustic processing device 100.

  The input device 16 is a device (for example, a mouse or a keyboard) for a user to input an instruction to the sound processing device 100. By appropriately operating the input device 16, the user can arbitrarily instruct the acoustic processing device 100 to perform either the localization component position (direction) or the localization component enhancement / suppression processing. It is.

  As shown in FIG. 1, the sound processing device 100 is realized by a computer system including an arithmetic processing device 22 and a storage device 24. The storage device 24 stores a program PG executed by the arithmetic processing device 22 and data used by the arithmetic processing device 22. A known recording medium such as a semiconductor recording medium or a magnetic recording medium or a combination of a plurality of types of recording media is arbitrarily adopted as the storage device 24. A configuration in which the acoustic signal SIN (SIN_L, SIN_R) is stored in the storage device 24 (therefore, the signal supply device 12 can be omitted) is also suitable.

  The arithmetic processing unit 22 executes a program PG stored in the storage device 24 to thereby generate a plurality of functions (variable setting unit 32, frequency analysis unit 34, coefficient setting unit) for generating the acoustic signal SOUT from the acoustic signal SIN. 36, a signal processing unit 38, and a waveform synthesis unit 40). A configuration in which each function of the arithmetic processing unit 22 is distributed over a plurality of integrated circuits, or a configuration in which a dedicated electronic circuit (DSP) realizes each function may be employed.

  The variable setting unit 32 sets the localization variable α to be variable. The localization variable α is a variable that designates the position (direction) of the sound image of the localization component. The variable setting unit 32 of the present embodiment variably sets the localization variable α (0 ≦ α ≦ 1) in accordance with an instruction from the user to the input device 16. For example, when the localization variable α is 0.5 (median value), the center (front) direction is indicated. Further, as the localization variable α is closer to 1, a rightward direction is indicated, and as the localization variable α is closer to 0, a leftward direction is indicated. The user can change the localization variable α by operating the input device 16 at any time while listening to the reproduced sound from the sound emitting device 14.

The frequency analysis unit 34 sequentially generates a frequency spectrum (complex spectrum) LA of the acoustic signal SIN_L and a frequency spectrum (complex spectrum) RA of the acoustic signal SIN_R for each unit section (frame) on the time axis. The frequency spectrum LA is a series of frequency components LAk (e ^jω ) (LA1 (e ^jω ) to LAK (e ^jω )) corresponding to each of K frequencies (frequency bands) f1 to fK (k = 1 to 1). K). The symbol j means an imaginary unit. Similarly, the frequency spectrum RA is a series of frequency components RAk (e ^jω ) (RA1 (e ^jω ) to RAK (e ^jω )) corresponding to each of the frequencies f1 to fK. For the generation of the frequency spectrum LA and the frequency spectrum RA, a known frequency analysis such as a short-time Fourier transform may be arbitrarily employed. A filter bank composed of K band pass filters having different pass bands can also be adopted as the frequency analysis unit 34.

  The coefficient setting unit 36 in FIG. 1 includes a processing coefficient sequence Ge for enhancing the localization component of the acoustic signal SIN (SIN_L, SIN_R) and a processing coefficient sequence for suppressing the localization component of the acoustic signal SIN. Gs. The processing coefficient sequence Ge and the processing coefficient sequence Gs are sequentially generated for each unit section using the frequency spectrum LA and the frequency spectrum RA. The processing coefficient sequence Ge is a series of coefficient values Ge [k] (Ge [1] to Ge [K]) corresponding to each of the frequencies f1 to fK, and the processing coefficient sequence Gs is assigned to each of the frequencies f1 to fK. This is a series of corresponding coefficient values Gs [k] (Gs [1] to Gs [K]).

The coefficient value Ge [k] and the coefficient value Gs [k] correspond to a gain (spectral gain) with respect to the frequency component LAk (e ^jω ) of the acoustic signal SIN_L and the frequency component RAk (e ^jω ) of the acoustic signal SIN_R. It is variably set within the range of 0 or more and 1 or less according to the characteristics of SIN (SIN_L, SIN_R) (0 ≦ Ge [k] ≦ 1, 0 ≦ Gs [k] ≦ 1). Specifically, the coefficient values Ge [1] to Ge [K] of the processing coefficient sequence Ge for emphasizing the localization component are set to 1 as the coefficient value Ge [k] of the frequency fk having a large localization component power (amplitude). Set to a close number. On the other hand, the coefficient values Gs [1] to Gs [K] of the processing coefficient sequence Gs for suppressing the localization component are set to values closer to 0 as the coefficient value Gs [k] of the frequency fk having a larger localization component power. .

The signal processing unit 38 of FIG. 1 causes the processing coefficient sequence Ge or the processing coefficient sequence Gs generated by the coefficient setting unit 36 to individually act (typically multiply) each of the frequency spectrum LA and the frequency spectrum RA. The frequency spectrum LB and the frequency spectrum RB are sequentially generated for each unit section. The frequency spectrum LB is a series of frequency components LBk (e ^jω ) (LB1 (e ^jω ) to LBK (e ^jω )) corresponding to each of the frequencies f1 to fK, and the frequency spectrum RB is each of the frequencies f1 to fK. Is a series of frequency components RBk (e ^jω ) corresponding to (RB1 (e ^jω ) to RBK (e ^jω )). For the processing of the frequency spectrum LA and the frequency spectrum RA of each unit section, the processing coefficient sequence Ge or the processing coefficient sequence Gs generated by the coefficient setting unit 36 for the unit section is applied.

When the user instructs the input device 16 to emphasize the localization component, the signal processing unit 38 processes the frequency spectrum LA and the frequency spectrum RA as shown in the following formulas (1a) and (1b). A frequency spectrum LB and a frequency spectrum RB are generated by multiplication of the coefficient sequence Ge. That is, the frequency components LBk of each frequency fk in the frequency spectrum ^LB (e jω) is set to the multiplication value between the frequency component of the frequency fk LAk ^(e jω) and the coefficient value Ge [k] (Formula (1a)) , the frequency components RBk of each frequency fk in the frequency spectrum ^RB (e jω) is set to the multiplication value between the frequency component of the frequency fk RAk ^(e jω) and the coefficient value Ge [k] (equation (1b)) . Therefore, the frequency spectrum LB and the frequency spectrum RB in which the localization component of the acoustic signal SIN (SIN_L, SIN_R) is emphasized are generated.

On the other hand, when the user instructs the input device 16 to suppress the localization component, the signal processing unit 38, as shown in the following equations (2a) and (2b), the frequency spectrum LB and the frequency spectrum RB The processing coefficient sequence Gs for suppressing the localization component is applied to the generation of. That is, each frequency component LBk (e ^jω ) of the frequency spectrum LB is calculated by multiplying each frequency component LAk (e ^jω ) of the frequency spectrum LA by each coefficient value Gs [k] of the processing coefficient sequence Gs (formula (2a )), calculates the respective frequency components of the frequency spectrum RB RBk ^(e jω) by multiplying the each frequency component RAk of the frequency spectrum RA (e ^{j [omega])} and the coefficient value Gs [k] (formula (2b)). Therefore, the frequency spectrum LB and the frequency spectrum RB in which the localization component of the acoustic signal SIN (SIN_L, SIN_R) is suppressed are generated.

  The waveform synthesizer 40 in FIG. 1 generates a stereo acoustic signal SOUT_L and an acoustic signal SOUT_R from the frequency spectrum LB and the frequency spectrum RB processed by the signal processor 38. Specifically, the waveform synthesizer 40 generates the acoustic signal SOUT_L by converting the frequency spectrum LB for each unit section into a signal in the time domain by inverse Fourier transform and mutually connecting the preceding and following unit sections. Similarly, the waveform synthesizer 40 generates an acoustic signal SOUT_R from each frequency spectrum RB. The acoustic signals SOUT (SOUT_L, SOUT_R) generated by the waveform synthesis unit 40 are supplied to the sound emitting device 14 and reproduced as sound waves.

  As described above, in the first embodiment, each of the acoustic signal SIN_L (frequency spectrum LA) and the acoustic signal SIN_R (frequency spectrum RA) is individually multiplied by the processing coefficient sequence Ge or the processing coefficient sequence Gs. Therefore, the acoustic signal SOUT (SOUT_L, SOUT_R) in which the localization component is emphasized or suppressed can be generated in the stereo format.

Next, details of the coefficient setting unit 36 will be described. FIG. 2 is a block diagram of the coefficient setting unit 36. As shown in FIG. 2, the coefficient setting unit 36 includes a sum component generation unit 52, a difference component generation unit 54, and a coefficient sequence generation unit 60. The sum component generation unit 52 adds the frequency components LA1 (e ^jω ) to LAK (e ^jω ) of the acoustic signal SIN_L and the frequency components RA1 (e ^jω ) to RAK (e ^jω ) of the acoustic signal SIN_R for each unit interval. A sum component (complex spectrum) M is sequentially generated. The sum component M is a series of frequency components Mk (e ^jω ) (M1 (e ^jω ) to MK (e ^jω )) corresponding to each of the frequencies f1 to fK. As shown in Equation (3), the frequency component Mk (e ^jω ) of the frequency fk of the sum component M is the addition (complex number) of the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) of the frequency fk. It corresponds to. Therefore, the sum component M corresponds to a monaural signal in which sounds from all sound sources are mixed. A configuration in which a weighted sum or average of the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) is calculated as the sum component M may be employed.

2 performs subtraction between the frequency components LA1 (e ^jω ) to LAK (e ^jω ) of the acoustic signal SIN_L and the frequency components RA1 (e ^jω ) to RAK (e ^jω ) of the acoustic signal SIN_R. Thus, a difference component (complex spectrum) S is sequentially generated for each unit interval. The difference component S is a series of frequency components Sk (e ^jω ) (S1 (e ^jω ) to SK (e ^jω )) corresponding to each of the frequencies f1 to fK. The difference component generator 54 calculates the frequency components S1 (e ^jω ) to SK (e ^jω ) by the calculation (weighted subtraction) of Expression (4) using the localization variable α set by the variable setting unit 32.

As it is understood from the formula (4), varying proportions frequency components at (weight value) LAk (e ^{j [omega])} from a frequency component RAk (e ^{j [omega])} subtraction (reverse phase addition) according to the localization variable α Thus, each frequency component Sk (e ^jω ) of the difference component S is generated. Therefore, the difference component S is a signal in which the localization component in the position (direction) corresponding to the localization variable α in the acoustic signal SIN (SIN_L, SIN_R) is relatively suppressed with respect to other components (that is, other than the localization component). Signal with relatively emphasized components). For example, when the localization variable α is 0.5 (median value), a difference component S in which a localization component in the center direction (that is, a component having substantially the same amplitude and phase) is suppressed is generated. Further, as the localization variable α exceeds 0.5, the localization component closer to the center direction is suppressed by the difference component S, and as the localization variable α is less than 0.5, the localization component toward the left side relative to the center direction is suppressed. However, the difference component S is suppressed.

The symbol max (α, 1-α) in Equation (4) means the maximum value of the localization variable α or the variable (1-α). Since the localization variable α is set to a numerical value of 1 or less, there is a possibility that the power (amplitude) of the frequency component Sk (e ^jω ) is insufficient only by the calculation of the numerator of Equation (4). Dividing by the maximum value max (α, 1-α) as in Equation (4) is equivalent to the power of the frequency component Sk (e ^jω ) and the frequency component LAk (e ^jω ) or frequency component RAk (e ^jω ). It is for maintaining.

  2 uses the sum component M generated by the sum component generation unit 52 and the difference component S generated by the difference component generation unit 54 to process the localization component enhancement processing coefficient sequence Ge (Ge [1] to Ge [K]) and a processing coefficient sequence Gs (Gs [1] to Gs [K]) for suppressing the localization component are generated. As shown in FIG. 2, the coefficient sequence generation unit 60 includes a first generation unit 62, a second generation unit 64, a third generation unit 66, and a synthesis unit 68.

The first generation unit 62 generates a numerical sequence CA for emphasizing the localization component from the sum component M and the difference component S. The numerical sequence CA is a series (CA [1] to CA [K]) of coefficient values (gains) CA [k] corresponding to the frequencies f1 to fK. Specifically, the first generation unit 62 calculates each coefficient value CA [k] of the numerical sequence CA by the calculation of the following mathematical formula (5).

The symbol P [k] in Equation (5) means the power at the frequency fk in the power spectrum P in which the localization component is emphasized. The power P [k] is calculated by, for example, the following formula (6a) and formula (6b).

As is understood from the formula (6a), the power of the frequency component ^{Mk (e jω) | Mk (} e jω) | 2 is the power of the frequency component ^{Sk (e jω) | Sk (} e jω) | 2 over the frequency fk The power P [k] is set to a value obtained by subtracting the power | Sk (e ^jω ) | ² of the difference component S from the power | Mk (e ^jω ) | ² of the sum component M. That is, the power spectrum P is generated by subtraction (spectrum subtraction) between the power spectrum of the sum component M and the power spectrum of the difference component S. On the other hand, the power ^| Mk (e jω) | ² is the power ^| Sk (e jω) | Power P [k] of ² or less and comprising frequency fk is the sum component M Power ^| Mk (e jω) | ² a predetermined It is set to the product of the coefficient (flooring coefficient) β. As can be understood from the above description, the calculations of Equation (6a) and Equation (6b) are performed when the sum component M is assumed to be a signal component (target sound) and the difference component S is assumed to be a noise component. This corresponds to spectral subtraction (SS). Note that dividing the amplitude P [k] ^1/2 by the amplitude | Mk (e ^jω ) | of the frequency component Mk (e ^jω ) | in equation (5) is a numerical value of 1 or less. This is for normalization to (0 ≦ CA [k] ≦ 1).

Since the frequency component Sk (e ^jω ) is a component in which the localization component is suppressed, the series of powers P [1] to P [K] calculated by the equations (6a) and (6b) is the acoustic signal SIN (SIN_L , SIN_R), the power spectrum P of the component emphasizing the localization component. Therefore, the coefficient values CA [1] to CA [K] of the numerical value sequence CA calculated by the equation (5) are the coefficient values CA of the frequency fk at which the power (amplitude) of the localization component at the position corresponding to the localization variable α is large. [k] is a numerical value closer to 1, and the coefficient value CA [k] of the frequency fk having a smaller localization component power is a numerical value closer to 0.

As understood from the above description, the numerical value sequence CA generated by the first generation unit 62 is used as the processing coefficient sequence Ge (the coefficient value CA [k] is expressed as the coefficient value Ge [k] in the equations (1a) and (1b)). ] as), but the acoustic signal SIN_L frequency components LAk (e ^{j [omega])} and respectively multiplying the configuration of an audio signal SIN_R frequency components RAk ^(e jω) (hereinafter referred to as "comparison example"), stereo localization component is emphasized It is possible to generate an acoustic signal SOUT (SOUT_L, SOUT_R) in the form.

However, when the acoustic signal SIN_L (frequency component LAk (e ^jω )) and the acoustic signal SIN_R (frequency component RAk (e ^jω )) are different in phase, the localization component is not sufficiently suppressed in the calculation of Equation (4). The localization component remains with a significant power in the difference component S. As described above, the localization component remaining in the difference component S is subtracted from the sum component M by the calculation of Equation (6a) (that is, the power of the localization component in the power spectrum P is reduced). Thus, as the phase difference of the frequency components LAk and (e ^{j [omega])} and the frequency component of the acoustic signal SIN_R RAk ^(e jω) of the acoustic signal SIN_L large coefficient values CA [k numerical sequence CA that first generation unit 62 generates ] Tends to be a small number. That is, in the comparative configuration using the numerical value sequence CA as the processing coefficient sequence Ge, the effect of enhancing the localization component is insufficient. When the sound signal SIN (SIN_L, SIN_R) of the sound after reflection in the acoustic space (reverberation sound) is generated by sound collection using two sound collection devices installed at positions separated from each other, When the reverberation effect is given to the signal SIN, the phase difference between the acoustic signal SIN_L and the acoustic signal SIN_R becomes significant, and thus the lack of emphasis on the localization component in the comparison becomes particularly obvious.

Therefore, the second generation unit 64 generates a numerical sequence CB corresponding to the phase difference between the acoustic signal SIN_L (frequency component LAk (e ^jω )) and the acoustic signal SIN_R (frequency component RAk (e ^jω )). The numerical sequence CB is a series (CB [1] to CB [K]) of coefficient values CB [k] corresponding to the frequencies f1 to fK. As the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) of the frequency fk increases, the coefficient value CB [k] of the frequency fk in the numerical sequence CB is set to a larger value.

3, the frequency component of the acoustic signal SIN_L LAk ^(e jω) and the frequency component Mk (e ^{j [omega])} of the frequency component RAk (e ^{j [omega])} and sum component M of the acoustic signal SIN_R and a vector in the complex plane (where each The component codes are abbreviated as LA, RA, M). The angle θ between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) corresponds to the phase difference between the two. In FIG. 3, the amplitude of the frequency component ^LAk (e jω) | exemplifying a case and are equal conveniently ^| LAk (e jω) | and the amplitude of the frequency component ^{RAk (e jω) | RAk (} e jω) .

When the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) are in phase (θ = 0) as shown in part (A) of FIG. 3, the amplitude | Mk (e ^jω ) | of the sum component M the amplitude of the frequency component ^LAk (e jω) | matches the sum of the (hereinafter referred to as "amplitude ^{sum") Ak | LAk (e jω)} | and the amplitude of the frequency component ^{RAk (e jω) | RAk (} e jω) (Ak = | LAk (e ^jω ) | + | RAk (e ^jω ) |). On the other hand, as shown in part (B) and part (C) of FIG. 3, the larger the phase difference (angle θ) between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ), The amplitude | Mk (e ^jω ) | is smaller than the amplitude sum Ak. That is, the greater the difference between the amplitude sum Ak and the amplitude | Mk (e ^jω ) | of the sum component M (the smaller the amplitude | Mk (e ^jω ) | is smaller than the amplitude sum Ak), the more the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) tend to be large. Using the above tendency, the second generation unit 64 of the first embodiment uses the amplitude sum Ak of the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) and the amplitude | Mk (e ^jω ) | Is determined according to the result of comparison with each coefficient value CB [k] (CB [1] to CB [K]) of the numerical sequence CB.

As shown in FIG. 4, the second generation unit 64 includes an amplitude calculation unit 642 and a setting unit 644. Amplitude calculating unit 642, each of the amplitudes of the frequency components ^{LA1 (e jω) ~LAK (e} jω) | LAk (e jω) | and, each of the amplitudes of the frequency components ^{RA1 (e jω) ~RAK (e} jω) | RAk (e ^jω ) | and the amplitude | Mk (e ^jω ) | of each frequency component M1 (e ^jω ) to MK (e ^jω ) of the sum component M generated by the sum component generation unit 52 for each unit section Calculate sequentially. The setting unit 644 uses the amplitudes calculated by the amplitude calculation unit 642 to variably set the coefficient values CB [k] of the numerical value sequence CB within a range of 1 or more (CB [k] ≧ 1).

Specifically, for each of frequencies f1 to fK, setting unit 644 sets amplitude sum Ak of amplitude | LAk (e ^jω ) | and amplitude | RAk (e ^jω ) | and amplitude | Mk (e ^{jω of} sum component M). ) | Is calculated as ΔAk (ΔAk = | LAk (e ^jω ) | + | RAk (e ^jω ) | − | Mk (e ^jω ) |), and the coefficient value CB [k] increases as the difference ΔAk increases. Set to a numeric value. When the difference ΔAk is 0, the setting unit 644 sets the coefficient value CB [k] to 1, for example. A specific method for the setting unit 644 to determine the coefficient value CB [k] from the difference ΔAk is arbitrary. For example, from the table in which each numerical value of the difference ΔAk and each numerical value of the coefficient value CB [k] are associated with each other. There are a method of searching for the coefficient value CB [k] and a method of calculating the coefficient value CB [k] by calculation of an arithmetic expression that defines the coefficient value CB [k] using the difference ΔAk as a variable (for example, an increasing function with respect to the difference ΔAk). Is preferred. As described above, as the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) increases (the difference ΔAk increases), the coefficient value CB [k] of each numerical value sequence CB increases. Set to

  2 generates a processing coefficient sequence Ge (Ge [1] to Ge [K]) from the numerical sequence CA generated by the first generating unit 62 and the numerical sequence CB generated by the second generating unit 64. To do. The coefficient value Ge [k] of the frequency fk of the processing coefficient sequence Ge is, for example, a multiplication value of the coefficient value CA [k] of the frequency fk of the numerical sequence CA and the coefficient value CB [k] of the frequency fk of the numerical sequence CB ( Ge [k] = CA [k] × CB [k]). However, when the multiplication value of the coefficient value CA [k] and the coefficient value CB [k] exceeds 1, the synthesis unit 68 sets the coefficient value Ge [k] to 1.

As can be understood from the above description, the position of the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) increases as the component of the frequency fk becomes dominant in the localization component at the position corresponding to the localization variable α. As the phase difference is larger, the coefficient value Ge [k] of the processing coefficient sequence Ge is set to a larger numerical value. Therefore, even when the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) is large, the signal processing unit 38 multiplies each of the frequency spectrum LA and the frequency spectrum RA by the processing coefficient sequence Ge. It is possible to generate stereo-type acoustic signals SOUT (SOUT_L, SOUT_R) in which the localization component is sufficiently emphasized.

The third generation unit 66 in FIG. 2 uses the processing coefficient sequence Ge generated by the synthesis unit 68 to generate a processing coefficient sequence Gs (a sequence of coefficient values Gs [1] to Gs [K]) for suppressing the localization component. Generate. Specifically, as shown in Equation (7), the third generation unit 66 subtracts each coefficient value Ge [k] of the processing coefficient sequence Ge from a predetermined value (1 in this embodiment) to thereby process the processing coefficient sequence. Each coefficient value Gs [k] of Gs is calculated.

  As understood from the equation (7), the coefficient values Gs [1] to Gs [K] of the processing coefficient sequence Gs generated by the third generation unit 66 are the powers of the localization components at positions corresponding to the localization variable α ( The coefficient value Gs [k] of the frequency fk having a larger amplitude) is closer to 0, and the coefficient value Gs [k] of the frequency fk having a smaller localization component power is closer to 1. Accordingly, the signal processing unit 38 multiplies each of the frequency spectrum LA and the frequency spectrum RA by the processing coefficient sequence Gs, thereby generating the stereo-type acoustic signal SOUT (SOUT_L, SOUT_R) in which the localization component is suppressed as described above. The

By the way, in the above-described comparison, a configuration may be adopted in which the processing coefficient sequence Gs for suppression is generated using the numerical sequence CA generated by the first generation unit 62 as the processing coefficient sequence Ge of Equation (7) (Gs [k]). = 1-CA [k]). However, the larger the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) is, the smaller the coefficient value CA [k] of the numerical sequence CA becomes. Therefore, in the proportional configuration, the frequency component LAk The larger the phase difference between (e ^jω ) and the frequency component RAk (e ^jω ), the larger the coefficient value Gs [k] of the processing coefficient sequence Gs. Therefore, there arises a problem that the localization component is not sufficiently suppressed. On the other hand, in the first embodiment, the larger the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ), the larger the coefficient value Ge [k] becomes, so the frequency component LAk (e ^jω ) The coefficient value Gs [k] of the processing coefficient sequence Gs becomes a smaller numerical value as the phase difference between the frequency component RAk (e ^jω ) increases. Therefore, even when the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) is large, it is possible to generate a stereo-type acoustic signal SOUT (SOUT_L, SOUT_R) in which the localization component is sufficiently suppressed. It is.

As described above, in the first embodiment, the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) is reflected in the processing coefficient sequence Ge and the processing coefficient sequence Gs. Even when there is a phase difference between the component LAk (e ^jω ) and the frequency component RAk (e ^jω ), there is an advantage that the effect of emphasizing or suppressing the localization component can be sufficiently maintained.

  By the way, in Japanese Patent No. 3670562, either an attenuation coefficient gi (k) corresponding to the amplitude ratio between channels of a stereo signal or an attenuation coefficient gp (k) corresponding to a phase difference is selected and each channel is selected. A configuration for multiplying an acoustic signal is disclosed. However, in the above technique, the attenuation coefficient gi (k) according to the amplitude ratio and the attenuation coefficient gp (k) according to the phase difference are alternatively applied. If they are different, there is a problem that it is difficult to properly emphasize or suppress the localization component. On the other hand, in the first embodiment, the sum component M and the difference component S calculated as a complex spectrum from the acoustic signal SIN_L (frequency spectrum LA) and the acoustic signal SIN_R (frequency spectrum RA) are processed coefficient sequence Ge and processing coefficient sequence Gs. Therefore, the processing coefficient sequence Ge and the processing coefficient sequence Gs reflecting both the amplitude difference and the phase difference between the acoustic signal SIN_L and the acoustic signal SIN_R are generated. Therefore, in addition to the case where only one of the amplitude and the phase is different between the acoustic signal SIN_L and the acoustic signal SIN_R, the localization component can be effectively enhanced or suppressed when both the amplitude and the phase are different. The effect of is realized.

<B: Second Embodiment>
A second embodiment of the present invention will be described. In the first embodiment, the comparison between the amplitude sum Ak of the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) and the amplitude | Mk (e ^jω ) | of the frequency component Mk (e ^jω ) of the sum component M is performed. The second generation unit 64 sets each coefficient value CB [k] of the numerical sequence CB according to the result. In the second embodiment, the angle θ between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) (that is, the phase difference between them) is calculated to set the coefficient value CB [k]. In the following examples, elements having the same functions and functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed descriptions thereof are appropriately omitted.

FIG. 5 is a schematic diagram showing the relationship among the frequency component LAk (e ^jω ), the frequency component RAk (e ^jω ), and the frequency component Mk (e ^jω ) of the sum component M. The triangle TML in FIG. 5 is a triangle having a frequency component LAk (e ^jω ) and a frequency component Mk (e ^jω ) as two sides, and the triangle TMR has a frequency component RAk (e ^jω ) and a frequency component Mk (e ^jω ). Is a triangle with two sides. The areas S of the triangle TML and the triangle TMR are equal to each other and are expressed by the following formula (8). The angle θ1 in the equation (8) is an angle between the frequency component LAk (e ^jω ) and the frequency component Mk (e ^jω ), and the angle θ2 is the frequency component RAk (e ^jω ) and the frequency component Mk (e ^jω ) Is the angle.

From the formula (8), the following formula (9a) and formula (9b) are derived.

On the other hand, the area S of the triangle having the frequency component LAk (e ^jω ), the frequency component RAk (e ^jω ), and the frequency component Mk (e ^jω ) as three sides is equal to the areas of the triangle TML and the triangle TMR. It is expressed by formula (10) (Heron formula).

The second generator 64 calculates the angle θ1 and the angle θ2 by applying the area S calculated by the calculation of the formula (10) to the formula (9a) and the formula (9b). Then, the second generation unit 64 calculates each coefficient value CB [k] of the numerical sequence CB by the following equation (11) using the angle θ1 and the angle θ2 (θ1 + θ2 <π / 2).

As understood from the equation (11), the phase difference of the frequency components LAk and (e ^{j [omega])} and the frequency component RAk (e ^{j [omega])} (angle (.theta.1 + .theta.2) coefficient of numerical sequence CB larger the value CB [k] is greater The method for generating the processing coefficient string Ge and the processing coefficient string Gs using the numerical value string CA and the numerical value string CB is the same as in the first embodiment.

In the second embodiment, the same operation and effect as in the first embodiment are realized. As it will be understood from the example of the first embodiment and the second embodiment, the second generator 64, the frequency component LAk of (e ^{j [omega])} the amplitude | LAk ^(e jω) | of the frequency component RAk ^(e jω) It is included as an element for generating each coefficient value CB [k] of the numerical sequence CB from the amplitude | RAk (e ^jω ) | and the amplitude | Mk (e ^jω ) | of the frequency component Mk (e ^jω ) | A specific method for calculating the numerical value CB [k] is arbitrary in the present invention.

<C: Modification>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined.

(1) Modification 1
The method of calculating each coefficient value CB [k] of the numerical value sequence CB is not limited to the above example. For example, as can be understood from the relationship illustrated in FIG. 3, the larger the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ), the larger the amplitude | Mk (e ^jω ) | Since the relative ratio Qk (Qk = Ak / | Mk (e ^jω ) |) of the amplitude sum Ak with respect to is a large numerical value, a configuration is adopted in which the relative ratio Qk is calculated as each coefficient value CB [k] of the numerical sequence CB. obtain. A configuration in which each coefficient value CB [k] is calculated by calculation (mapping) of a predetermined function using the difference ΔAk (ΔAk = Ak− | Mk (e ^jω ) |) or the relative ratio Qk as a variable is also suitable.

(2) Modification 2
In each of the above embodiments, the third generation unit 66 generates the processing coefficient sequence Gs for suppression from the processing coefficient sequence Ge for emphasis obtained by synthesizing the numerical value sequence CA and the numerical value sequence CB. In addition, a configuration in which the third generation unit 67 of FIG. 6 generates the processing coefficient sequence Gs may be employed.

  The third generation unit 67 of FIG. 6 includes a first calculation unit 672 and a second calculation unit 674. The first calculation unit 672 calculates a numerical sequence CD (sequence of coefficient values CD [1] to CD [K]) for suppressing the localization component from the numerical sequence CA generated by the first generation unit 62. For example, the first calculation unit 672 subtracts the coefficient value CA [k] of the numerical value sequence CA from a predetermined position (for example, 1), similarly to the above-described equation (7), to thereby obtain each coefficient value CD [ k] (CD [k] = 1-CA [k]). Accordingly, like the processing coefficient sequence Gs for suppression, the coefficient value CD [k] of the frequency fk at which the power of the localization component at the position corresponding to the localization variable α is large becomes a numerical value closer to 0.

6 operates a numerical sequence CB ′ corresponding to the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) on the numerical sequence CD generated by the first arithmetic unit 672. By doing so, a processing coefficient sequence Gs for suppression is generated. The numerical value sequence CB ′, contrary to the numerical value sequence CB in each of the above forms, is set so that the smaller the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ), the smaller the value. This is a series of numerical values CB ′ [1] to CB ′ [K]. For example, the relative ratio (| Mk (e ^jω ) | / Ak) of the amplitude | Mk (e ^jω ) | of the sum component M with respect to the amplitude sum Ak can be calculated as the coefficient value CB ′ [k]. For example, the second calculation unit 674 calculates a product value of the coefficient value CD [k] of the numerical value sequence CD and the coefficient value CB '[k] of the numerical value sequence CB ′ as the coefficient value Gs [k] of the processing coefficient sequence Gs. Do it. The same effects as those of the first embodiment are realized even with the configuration of FIG.

(3) Modification 3
In each of the above embodiments, all the coefficient values CB [1] to CB [K] of the numerical value sequence CB are applied to all the coefficient values CA [1] to CA [K] of the coefficient sequence CA, so that the processing coefficient sequence Ge is obtained. However, a configuration in which localization component enhancement / suppression is performed only for components within a predetermined frequency band is also suitable. For example, the processing in each of the above modes is executed only for the frequency band (for example, 100 kHz to 8 kHz) in which the power of human voice is concentrated in the acoustic signal SIN (reproduction is performed without processing for other bands).

Further, as illustrated below, the coefficient value CA [k], which is a problem of insufficient emphasis or suppression of the localization component due to the phase difference between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ), is used. A configuration in which the coefficient value CB [k] is applied in a limited manner may be employed.

  FIG. 7 shows the coefficient value CA [k] (vertical axis) and localization corresponding to the frequency fk of the component in which the sound image is localized in the central direction (α = 0.5) in the numerical sequence CA generated by the first generator 62. It is a schematic diagram which shows the relationship with the variable (alpha) (horizontal axis). As shown in FIG. 7, as the localization variable α instructed by the user is closer to 0.5, each coefficient sequence CA [k] of the numerical sequence CA is set to a value closer to 1. As understood from the above relationship, the component of the frequency fk whose coefficient value CA [k] exceeds the predetermined threshold value CA_TH is highly likely to be a localization component to be emphasized.

  Therefore, the combining unit 68 multiplies the coefficient value CA [k] exceeding the threshold value CA_TH among the coefficient values CA [1] to CA [K] of the numerical sequence CA by multiplying the coefficient value CB [k]. A configuration for calculating the numerical value Ge [k] may be employed. The coefficient value CA [k] below the threshold value CA_TH is adopted as the coefficient value Ge [k] without being multiplied by the coefficient value CB [k]. According to the above configuration, compared with the configuration of the first embodiment in which K coefficient values CB [1] to CB [K] are applied to K coefficient values CA [1] to CA [K], There is an advantage that the processing load (the number of multiplications) by the combining unit 68 is reduced.

  Similarly, in the configuration of FIG. 6 in which the coefficient value CB ′ [k] is applied to the coefficient value CD [k] (CD [k] = 1−CA [k]) to generate the processing coefficient sequence Gs for suppression. A configuration in which the coefficient value CB ′ [k] is limitedly applied to the specific coefficient value CD [k] may be employed.

  8 shows the frequency fk of the component in which the sound image is localized in the central direction (α = 0.5) in the coefficient sequence CD generated by the first calculation unit 672 of the third generation unit 67 under the configuration of FIG. It is a schematic diagram which shows the relationship between corresponding coefficient value CD [k] (vertical axis) and localization variable (alpha) (horizontal axis). As shown in FIG. 8, the coefficient value CD [k] of the numerical sequence CD is set to a value closer to 0 as the localization variable α instructed by the user is closer to 0.5. As understood from the above relationship, the component of the frequency fk whose coefficient value CD [k] is lower than the predetermined threshold value CD_TH is highly likely to be a localization component to be suppressed.

  Therefore, the second arithmetic unit 674 in FIG. 6 restricts the coefficient value CB ′ [k] for the coefficient value CD [k] below the threshold value CD_TH among the coefficient values CD [1] to CD [K] of the numerical sequence CD. ] To calculate the coefficient value Gs [k]. The coefficient value CD [k] exceeding the threshold value CD_TH is adopted as the coefficient value Gs [k] without being multiplied by the coefficient value CB ′ [k]. According to the above configuration, the second calculation is performed as compared with the configuration in which the K coefficient values CB '[1] to CB' [K] are applied to the K coefficient values CD [1] to CD [K]. There is an advantage that the processing load (number of multiplications) by the unit 674 is reduced.

(4) Modification 4
The phase difference φk between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) corresponding to the localization component frequency fk changes according to the direction of the localization component according to the localization variable α. For example, the phase difference φk between the frequency component LAk (e ^jω ) of the localization component in the central direction (α = 0.5) and the frequency component RAk (e ^jω ) is a value close to 0, and the direction of the localization component is changed from the central direction. The phase difference φk increases as the distance increases (the localization variable α increases from the median (0.5)). Therefore, as shown in FIG. 9, assuming a range A having a predetermined width including the phase difference φa corresponding to the localization variable α, the phase difference φk between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) is There is a high possibility that the component of the frequency fk within the range A corresponds to the localization component.

Therefore, among the coefficient values CA [1] to CA [K] of the coefficient sequence CA, each frequency fk (that is, the phase difference φk between the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) within the range A (that is, A configuration in which the synthesis unit 68 operates the coefficient value CB [k] of the numerical value sequence CB can be adopted by limiting to each coefficient value CA [k] of the frequency fk) of the localization component. Each coefficient value CA [k] of the frequency fk where the phase difference φk is outside the range A is adopted as the coefficient value Ge [k] without being multiplied by the coefficient value CB [k]. The same applies to the configuration of FIG. 6, and a configuration in which each coefficient value CD [k] of the frequency k having the phase difference φk within the range A is multiplied by the coefficient value CB ′ [k] in a limited manner can be adopted.

(5) Modification 5
The method of generating the processing coefficient sequence Ge and the processing coefficient sequence Gs from the numerical value sequence CA and the numerical value sequence CB can be appropriately changed. For example, a configuration may be adopted in which an addition value of each coefficient value CA [k] of the numerical value sequence CA and each coefficient value CB [k] of the numerical value sequence CB is calculated as the coefficient value Ge [k] of the processing coefficient sequence Ge. Similarly, the configuration of FIG. 6 may employ a configuration in which the coefficient value Gs [k] is calculated by adding each coefficient value CD [k] and each coefficient value CB ′ [k].

(6) Modification 6
In each of the above embodiments, as understood from the equation (4), the ratio of the amplitude of the acoustic signal SIN_L (frequency component LAk (e ^jω )) and the acoustic signal SIN_R (frequency component RAk (e ^jω )) is a localization variable. Although the difference component S is calculated so as to change linearly according to α, as illustrated in the following embodiments, the calculation method of the sum component M and the difference component S and the relationship with the localization variable α are appropriately determined. Be changed.

<First aspect>
^LAk (e jω) | | ² and the power of the acoustic signal ^SIN_R | RAk (e jω) | power of the acoustic signal SIN_L configured to calculate the ² from the sum component M and the difference component S may be employed. Specifically, the sum component generation unit 52 generates a sum component M (complex spectrum composed of frequency components M1 (e ^jω ) to MK (e ^jω )) by the calculation of the following formula (12a), and the difference The component generation unit 54 generates a difference component S (a complex spectrum composed of frequency components S1 (e ^jω ) to SK (e ^jω )) by calculation of the following formula (12b). Therefore, in the difference component S, the power ratio between the acoustic signal SIN_L and the acoustic signal SIN_R changes linearly according to the localization variable α. Symbols e ^jL in equation (12a) and Equation (12b) means a phase spectrum of the frequency spectrum LA, symbol e ^jR means the phase spectrum of the frequency spectrum RA.

When the sum component M and the difference component S are generated by the above method, the first generation unit 62 of the coefficient sequence generation unit 60 generates a power spectrum P (power P [k]) in which the localization component is emphasized by the following formula ( The coefficient values Ge [k] of the processing coefficient sequence Ge are calculated by the calculation of the formula (14) using the power spectrum P, which is generated by the calculations of 13a) and (13b). The method by which the third generation unit 66 generates the processing coefficient sequence Gs from the processing coefficient sequence Ge is the same as in the first embodiment (Formula (7)). With the above configuration, the same effect as that of the first embodiment is realized.

<Second aspect>
A configuration in which the position (direction) of the localization component is controlled according to the function f (α) of the localization variable α can be adopted. Specifically, the sum component generation unit 52 generates the sum component M (frequency components M1 (e ^jω ) to MK (e ^jω )) by the calculation of the following formula (15a), and the difference component generation unit 54 The difference component S (frequency components S1 (e ^jω ) to SK (e ^jω )) is generated by the calculation of the following formula (15b). Therefore, the ratio of the amplitudes of the acoustic signal SIN_L and the acoustic signal SIN_R in the difference component S changes according to the function f (α) of the localization variable α. The coefficient sequence generation unit 60 calculates the processing coefficient sequence Ge and the processing coefficient sequence Gs from the sum component M of the formula (15a) and the difference component S of the formula (15b) by the same method as each of the above embodiments.

In Equation (6a), the difference between the power of the sum component M | Mk (e ^jω ) | ² and the power of the difference component S | Sk (e ^jω ) | ² is calculated as the power P [k]. As shown in the equation (6c), a configuration is also employed in which the difference between the amplitude | Mk (e ^jω ) | of the sum component M and the amplitude | Sk (e ^jω ) | of the difference component S is calculated as the amplitude P [k]. obtain. In the configuration in which the amplitude P [k] is calculated using the equation (6c), the first generation unit 62 calculates the coefficient value Ge [k] of the processing coefficient sequence Ge by the calculation of the equation (5a).

(7) Modification 7
In each of the above embodiments, the processing coefficient sequence Ge is calculated by subtraction of the power spectrum (Formula (6a), Formula (13a)) or subtraction of the amplitude spectrum (Formula (6c)), but a method of calculating the processing coefficient sequence Ge Is optional. For example, if the localization component included in the sum component M is assumed to be a signal component and the difference component S is assumed to be a noise component, the generation of the processing coefficient sequence Ge using the sum component M and the difference component S may include a noise component (difference). A known speech enhancement technique for generating a numerical sequence (processing coefficient sequence Ge) for emphasizing a signal component (localization component) by suppressing the component S) can be similarly applied.

  Examples of technologies that can be applied to the generation of the processing coefficient sequence Ge include speech enhancement using a Wiener filter and speech enhancement using an MMSE-STSA method or a MAP (maximum a posteriori estimation) estimation method. Can be done. For the MMSE-STSA method, see Y. Ephraim and D. Malah, "Speech enhancement using a minimum mean-square error short-time spectral amplitude estimator", IEEE ASSP, vol.ASSP-32, no.6, p.1109- 1121, Dec. 1984, MAP estimation method is described in T. Lotter and P. Vary, "Speech enhancement by MAP spectral amplitude estimation using a Super-Gaussian speech model", EURASIP Journal on Applied Signal Processing, vol.2005 , no, 7, p.1110-1126, July 2005.

(8) Modification 8
In each of the above embodiments, the processing coefficient sequence Gs is generated by the calculation (Formula (7)) using the processing coefficient sequence Ge. However, the coefficient sequence generation unit 60 performs the sum component M in the same manner as the generation of the processing coefficient sequence Ge. A configuration in which the processing coefficient sequence Gs is directly generated from the difference component S can also be adopted. Specifically, when the sum component M and the difference component S in each of the above-exemplified formulas are replaced with each other to generate the processing coefficient sequence Ge, the processing coefficient sequence Gs for suppressing the localization component can be generated. It is. That is, the processing coefficient sequence Ge and the processing coefficient sequence Gs in each of the above aspects can be replaced with each other.

  However, according to the configuration of the first embodiment in which the processing coefficient sequence Gs is calculated using the processing coefficient sequence Ge, processing for directly calculating the processing coefficient sequence Gs from the sum component M and the difference component S is not necessary. . Therefore, there is an advantage that the processing load by the coefficient sequence generator 60 is reduced. A processing coefficient sequence Gs is directly generated from the sum component M and the difference component S, and each coefficient value Gs [k] of the processing coefficient sequence Gs is subtracted from a predetermined value (for example, 1) in the same manner as the equation (7). Thus, a configuration for generating the processing coefficient sequence Ge (coefficient value Ge [k]) may be employed.

(9) Modification 9
In each of the above embodiments, the processing coefficient sequence G (Ge, Gs) is generated for each unit section, but the generation cycle of the processing coefficient sequence G is arbitrary. For example, a configuration in which the signal processing unit 38 applies the processing coefficient sequence G sequentially generated by the coefficient sequence generation unit 60 with a set of a predetermined number of unit intervals as a cycle may be adopted for a plurality of unit intervals in the cycle. In each of the above embodiments, the processing coefficient sequence G generated for each unit section is applied to the processing of the frequency spectrum (LA, RA) of the unit section. However, the processing coefficient sequence G of each unit section is used as the unit section. A configuration applied to the processing of the frequency spectrum (LA, RA) of each unit section after elapse of time can also be adopted.

(10) Modification 10
In each of the above embodiments, the processing coefficient sequence G (Ge, Gs) is multiplied by the frequency spectrum (LA, RA) of the acoustic signal SIN, but the content of processing by the signal processing unit 38 is appropriately changed. For example, a configuration in which the acoustic signal SOUT (SOUT_L, SOUT_R) is generated by subtracting the processing coefficient sequence G (Ge, Gs) from the frequency component LAk (e ^jω ) and the frequency component RAk (e ^jω ) may be employed. In contrast to the processing coefficient sequence Ge of the first embodiment, the processing coefficient sequence Ge for emphasis in the above configuration is set to a value closer to 0 as the coefficient value Ge [k] of the frequency fk where the power of the localization component is large. The The same applies to the processing coefficient sequence Gs for suppression. Contrary to the processing coefficient sequence Gs of the first embodiment, the coefficient value Gs [k] of the frequency fk having a large localization component power is set to a value closer to 1. The

(11) Modification 11
In each of the above embodiments, the coefficient sequence generation unit 60 generates both the processing coefficient sequence Ge for emphasizing the localization component and the processing coefficient sequence Gs for suppression, but the coefficient sequence generation unit 60 generates the processing coefficient sequence Ge and the processing coefficient. A configuration that generates only one of the columns Gs may also be employed. Therefore, for example, the third generation unit 66 of each of the above forms can be omitted.

(12) Modification 12
A configuration in which the coefficient β (flooring coefficient) in each of the above forms is variably set in accordance with an instruction from the user to the input device 16, for example, is also suitable. As the coefficient β is smaller (closer to 0), the degree of suppression of the localization component is strengthened and the degree of enhancement of the localization component is reduced. When the coefficient β is large, the coefficient value Gs [k] of most of the frequencies fk other than the localization component in the processing coefficient sequence Gs for suppression becomes a sufficiently small value, so that the acoustic signal SOUT (SOUT_L, SOUT_R) may be insufficient. Therefore, when the localization component is suppressed by setting the coefficient β to a large numerical value, a configuration in which the volume of the acoustic signal SOUT is increased is preferable. Similarly, when the coefficient β is small, the coefficient value Ge [k] of most of the frequencies fk in the emphasis processing coefficient string Ge can be a sufficiently small numerical value. When emphasizing the component, a configuration that increases the volume of the acoustic signal SOUT is preferably employed.

DESCRIPTION OF SYMBOLS 100 ... Sound processing device, 12 ... Signal supply device, 14 ... Sound emission device, 16 ... Input device, 22 ... Arithmetic processing device, 24 ... Memory | storage device, 32 ... Variable setting part, 34 ... Frequency analysis unit 36... Coefficient setting unit 38... Signal processing unit 40... Waveform synthesis unit 52 52 Sum component generation unit 54. Difference component generation unit 60 60 Coefficient sequence generation unit 62 ... First generation unit 64. Second generation unit 66. Third generation unit 68.

Claims (5)

First generation means configured to generate a first numerical sequence that is composed of coefficient values for each frequency and emphasizes or suppresses a localization component at a specific position in the stereo first acoustic signal and the second acoustic signal;
A second numerical sequence composed of coefficient values corresponding to a phase difference for each frequency between the first acoustic signal and the second acoustic signal is represented by both the amplitude of the first acoustic signal and the amplitude of the second acoustic signal. Second generation means for generating from the amplitude of the sum component of
Synthesis means for generating a first processing coefficient sequence composed of coefficient values for each frequency and emphasizing or suppressing the localization component from the first numerical value sequence and the second numerical value sequence;
An acoustic processing apparatus comprising: signal processing means for causing each coefficient value of the first processing coefficient sequence to act on each frequency component of the first acoustic signal and the second acoustic signal. The second generation means includes
Amplitude calculating means for calculating, for each frequency, an amplitude sum obtained by adding the amplitudes of the first acoustic signal and the second acoustic signal and the amplitude of the sum component;
The sound processing apparatus according to claim 1, further comprising: a setting unit that sets each coefficient value of the second numerical sequence according to a difference between the amplitude sum and the amplitude of the sum component. Sum component generating means for generating a sum component by adding the first acoustic signal and the second acoustic signal;
Difference component generation means for generating a difference component in which the localization component is suppressed by subtraction between the first acoustic signal and the second acoustic signal;
The first generation means generates the first numerical sequence from the sum component and the difference component,
The sound processing apparatus according to claim 1, wherein the second generation unit applies the amplitude of the sum component generated by the sum component generation unit to generation of the second numerical value sequence. The acoustic processing apparatus according to claim 3, wherein the first generation unit generates the first numerical value sequence according to a result of subtracting the other spectrum from one spectrum of the sum component and the difference component. A second processing coefficient sequence corresponding to the other of the localization component enhancement and suppression is generated by subtracting each coefficient value of the first processing coefficient sequence corresponding to one of the localization component enhancement and suppression from a predetermined value. The sound processing apparatus according to claim 1, further comprising third generation means.

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