JP2023012347A - Acoustic device and acoustic control method - Google Patents

Abstract

To provide an acoustic device and an acoustic control method that can perform proper surround reproduction according to a sound source signal.SOLUTION: An acoustic device comprises a separation part and an output control part. The separation part separates a predetermined sound source signal which requires no additional processing for pseudo reverberant sound from the sound source signal, and then removes the separated predetermined sound source signal from the sound source signal. The output control part applies a filter for generating a pseudo reverberant sound to the sound signal having the predetermined sound source signal removed by the separation part, and outputs the resulting signal.SELECTED DRAWING: Figure 1A

Description

The present invention relates to an acoustic device and an acoustic control method.

2. Description of the Related Art Acoustic devices that output sound source signals of various sound sources such as music and voice from a plurality of channels are conventionally known (see, for example, Patent Document 1). In the prior art, a pseudo-pseudo-reverberation sound generated from a sound source signal is positively added to the direct sound, and surround reproduction is performed on a plurality of channels.

Japanese Patent No. 5372142

However, the prior art still has room for improvement in terms of performing appropriate surround reproduction according to the sound source signal.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an acoustic device and an acoustic control method capable of performing appropriate surround reproduction according to sound source signals.

In order to solve the above problems and achieve the object, the present invention provides an audio device comprising a separator and an output controller. The separation unit separates a predetermined sound source signal that does not require a pseudo-reverberation adding process from the sound source signal, and removes the separated predetermined sound source signal from the sound source signal. The output control unit applies a filter for generating the pseudo-reverberation sound to the sound source signal from which the predetermined sound source signal has been removed by the separation unit, and outputs the sound source signal.

According to the present invention, appropriate surround reproduction can be performed according to the sound source signal.

FIG. 1A is a diagram explaining an outline of an acoustic control method according to the first embodiment. FIG. 1B is a diagram explaining an overview of the acoustic control method according to the first embodiment. FIG. 2 is a block diagram showing a configuration example of an audio system including the audio device according to the first embodiment. FIG. 3 is a diagram for explaining separation/extraction processing by the separation unit. FIG. 4A is a diagram for explaining a sound image of reproduced sound and the like. FIG. 4B is a diagram for explaining a sound image of reproduced sound and the like. FIG. 4C is a diagram for explaining a sound image of reproduced sound and the like. FIG. 4D is a diagram for explaining a sound image of reproduced sound and the like. FIG. 4E is a diagram for explaining a sound image of reproduced sound and the like. FIG. 4F is a diagram for explaining a sound image of reproduced sound. FIG. 4G is a diagram for explaining a sound image of reproduced sound. FIG. 5 is a flow chart showing a processing procedure executed by the audio device according to the first embodiment. FIG. 6 is a block diagram showing a configuration example of an audio system including an audio device according to the second embodiment. FIG. 7 is a diagram for explaining gain determination processing by the determination unit. FIG. 8 is a flow chart showing a processing procedure executed by the audio device according to the second embodiment.

Hereinafter, embodiments of the acoustic device and the acoustic control method disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

(First embodiment)
<Overview of Acoustic Control Method by Acoustic Device According to First Embodiment>
First, the outline of the sound control method by the sound device according to the first embodiment will be described below with reference to FIGS. 1A and 1B. 1A and 1B are diagrams for explaining the outline of the acoustic control method according to the first embodiment.

The sound control method according to the first embodiment is executed by, for example, the sound device 1 shown in FIG. 1A. In FIG. 1A, for example, in an interior space such as a vehicle cabin, direct sound and actual reverberant sound, which are sound source signals, are output from two speakers FR and FL arranged on the left and right in the front. A case is shown in which a pseudo-pseudo-reverberant sound is output from two arranged speakers RL and RR and added to the direct sound to perform surround reproduction.

Here, the sound source signal is, for example, a sound source signal having a spatial spread (sound image width) by outputting different sounds from two speakers FR and FL. That is, the sound source signal is a stereo signal that is stereo-reproduced by two channels (speakers FR and FL).

Further, the sound source signal is, for example, a sound in which a plurality of instrumental sounds and voices (vocal) such as classical music and opera are mixed, that is, a sound signal in which a plurality of sound sources are mixed, but is limited to this. is not. That is, the sound source signal may be a sound signal of voice only, or a sound signal of a single musical instrument (sound source) such as only a piano or only a violin.

Here, as shown in FIG. 1A, a listener (listener) L who listens to sound from a sound source S, which is a position where a sound source such as an instrumental sound or voice (vocal) is localized in a space, has two types of spaces. It is known that impressions can be perceived. One spatial impression is the sound image width ASW, which is defined as the “width of the apparent sound source” that is perceived as being fused with the direct sound both temporally and spatially. The sense of envelopment LEV is defined as "the feeling that the surroundings of the listener are filled with the sound source of the music." The sound image width ASW is the width of the sound image A derived from the direct sound and early reflected sound components, which are the initial components of the sound source signal. Also, the enveloping feeling LEV is the sound image B derived from the reverberant sound component, which is the late component of the sound source signal.

In order to design and evaluate the sound image width ASW and the feeling of envelopment LEV, an index using the so-called "law of the first wavefront" may be used. In such an index, two regions R1 and R2 defined by two thresholds TH1 and TH2 are defined as shown in FIG. 1B.

The region R1 is a region containing components (initial components) mainly containing direct sound among the components contained in the sound source signal. For example, when the initial component of the region R1 is large, the sound image width ASW is large. Therefore, the listener L perceives that the sound is diffused, and depending on the sound source, the sound quality is evaluated as being poor (unclear). Note that the direct sound is, for example, a sound recorded directly from a voice (vocal), musical instrument, or the like, and does not include sound reflected by walls or the like.

Further, the region R2 is a region that mainly includes components (late components) including reverberant sound among the components included in the sound source signal. For example, when the reverberation component in the region R2 is large, the enveloping feeling LEV increases. Note that the reverberating sound is, for example, the sound obtained by recording the sound of a voice, musical instrument, or the like that is reflected by a wall or the like, and is the sound that is temporally delayed from the direct sound.

In a relatively narrow space such as a passenger compartment, it is difficult to separate the direct sound and the reverberant sound, and the reverberant sound tends to be mixed with the direct sound. In such a case, the component of the reverberant sound in the region R2 becomes small, and the enveloping feeling LEV becomes small. Therefore, in a narrow space such as a vehicle compartment where direct sound and reverberant sound coexist, the acoustic device 1 positively adds a pseudo pseudo-reverberant sound to the direct sound to reduce the reverberation in the region R2. By enlarging the sound component, it is possible to ensure the wrapped feeling LEV.

In the above description, the direct sound or the like is output from the speakers FR and FL, and the pseudo-reverberation sound is output from the speakers RL and RR. However, the present invention is not limited to this. That is, for example, the acoustic device 1 may directly output sound or the like from all or some of the four speakers FR, FL, RL, and RR, and adjust the volume and the like. As a result, for example, the acoustic device 1 can move the spatial position of the sound image A such as the direct sound. Similarly, the acoustic device 1 may output pseudo-reverberant sound from all or some of the four speakers FR, FL, RL, and RR, and adjust the volume and the like. As a result, for example, the acoustic device 1 can move the spatial position of the sound image B of the pseudo-reverberant sound. In this manner, the acoustic device 1 can localize the sound image A such as the direct sound and the sound image B such as the pseudo-reverberant sound at arbitrary positions.

By the way, in the conventional technology, the surround component including the early reflected sound component is extracted from the sound source signal based on the correlation of the left and right channels of the sound source, and the extracted surround component is delayed and output to produce a pseudo-reverberation sound. was sometimes added. However, in such a case, it is not always possible to extract intended surround components from various types of sound source signals. Moreover, when the surround component is delayed and output as described above, the early reflection sound that originally existed cannot be obtained, and as a result, there is a possibility that appropriate surround reproduction cannot be performed.

Therefore, the audio device 1 according to the present embodiment is configured so as to be able to perform appropriate surround reproduction according to the sound source signal.

Hereinafter, the processing of the audio device 1 will be specifically described with reference to FIG. 1A. are separated, and the separated predetermined sound source signal is removed from the sound source signal (step S1). A detailed method for separating the predetermined sound source signal will be described later. Also, the predetermined sound source signal here includes, for example, an audio (vocal) component.

Next, the audio device 1 applies a filter for generating a pseudo-reverberation sound to the sound source signal from which the predetermined sound source signal has been removed (hereinafter, may be referred to as a “removed sound source signal”). A reverberation signal representing sound is generated and output from the speakers RL and RR (step S2). As the filter, for example, an impulse response filter such as an FIR (Finite Impulse Response) filter or an IIR (Infinite Impulse Response) filter can be used, but the filters are not limited to these.

As described above, in this embodiment, the filter is applied only to the sound source signal from which the predetermined sound source signal (for example, the voice component) that does not require the addition processing of the pseudo reverberation is removed, and the reverberation signal is generated. In other words, the filter is not applied to the predetermined sound source signal of the sound source signals, and no reverberation signal is generated.

As a result, even if the sound source signal includes, for example, a sound source signal that requires pseudo-reverberation addition processing and an unnecessary sound source signal (here, a predetermined sound source signal), the sound source signal that requires addition processing Since the reverberation signal is generated only for the sound source signal, appropriate surround sound reproduction can be performed according to the sound source signal (more specifically, according to the content (type) of the sound source signal).

Note that the audio component included in the predetermined sound source signal is not applied with the above-described filter, and is reproduced as direct sound. Therefore, the listener L is in a state of not feeling the feeling of envelopment LEV in the reproduced predetermined sound source signal (here, voice). This is because the person L can clearly hear the reproduced voice.

In the above, an example in which the filter is applied only to the sound source signal from which the predetermined sound source signal has been removed has been shown, but the present invention is not limited to this. That is, for example, the acoustic device 1 may apply a filter to both the sound source signal from which the predetermined sound source signal has been removed and the predetermined sound source signal. At this time, for the sound source signal from which the predetermined sound source signal has been removed, a reverberation signal is generated such that the reverberation level of the corresponding pseudo-reverberant sound is relatively large. A reverberation signal may be generated such that the reverberation level of is relatively small. The above-mentioned "reverberation level" is an index value indicating the degree of reverberation of the pseudo-reverberation sound in the room (in this case, the passenger compartment) when the reverberation signals are reproduced from the speakers RL and RR, for example.

Although the predetermined sound source signal includes the audio component in the above description, the present invention is not limited to this. That is, the predetermined sound source signal includes sounds that are too reverberant and unnatural when the feeling of envelopment LEV increases due to surround reproduction. May include transient sound components as they exist.

<Structure of Acoustic System Equipped with Acoustic Apparatus According to First Embodiment>
Next, the configuration of an audio system including the audio device 1 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration example of an acoustic system including the acoustic device 1 according to the first embodiment. In FIG. 2, only the components necessary for explaining the features of this embodiment are represented by functional blocks, and the description of general components is omitted.

In other words, each component illustrated in FIG. 2 is functionally conceptual and does not necessarily need to be physically configured as illustrated. For example, the specific forms of distribution and integration of each functional block are not limited to those shown in the figure, and all or part of them can be functionally or physically distributed in arbitrary units according to various loads and usage conditions.・It is possible to integrate and configure.

As shown in FIG. 2, the sound system 100 includes a sound device 1, a sound source device 50, various sensors 60, and a plurality of speakers FL, FR, RL, and RR. Although the acoustic system 100 according to this embodiment is mounted on a vehicle, it is not limited to this.

The sound source device 50 outputs a sound source signal to the acoustic device 1 . The sound source signal is, for example, a stereo signal. The sound source signal is output as different signals from the two speakers FL and FR, which are two channels, via the acoustic device 1, thereby forming a spatially expanded sound image.

Various sensors 60 include various sensors that detect the state of the vehicle. The various sensors 60 include, for example, the running state of the vehicle such as vehicle speed, the open/closed state of windows, the operating state of the air conditioner, the seated state of the passenger, fader adjustment instructions for the speakers FL, FR, RL, and RR (front-rear balance adjustment instructions by the passenger). , a sensor capable of detecting the presence or absence of automatic driving, etc., and outputs information indicating the detected state of the vehicle to the acoustic device 1 . In the above description, the state of the vehicle, such as the running state and the open/closed state of the windows, is specifically shown, but these are merely examples and are not limited.

A plurality of speakers FL, FR, RL and RR are connected to the audio device 1 . These speakers FL, FR, RL, and RR output signals output from the acoustic device 1 as sounds. For example, the speakers FL and FR output the direct sound, which is the sound source signal, and the speakers RL and RR output the pseudo-reverberation sound generated from the sound source signal, but the present invention is not limited to this.

The audio device 1 includes a control section 2 and a storage section 3 . The control unit 2 includes an acquisition unit 21 , a separation unit 22 and an output control unit 23 . The audio device 1 includes a computer and various circuits having, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), flash memory, input/output ports, and the like.

The CPU of the computer functions as an acquisition unit 21, a separation unit 22, and an output control unit 23 of the control unit 2 by reading and executing programs stored in the ROM, for example.

At least one or all of the acquisition unit 21, the separation unit 22, and the output control unit 23 of the control unit 2 is configured by hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). can also

Also, the storage unit 3 corresponds to a RAM or a flash memory. The RAM and flash memory can store information of various programs and the like. Note that the audio device 1 may acquire the above-described programs and various types of information via another computer or portable recording medium connected via a wired or wireless network.

The acquisition unit 21 acquires various information and signals. For example, the acquisition unit 21 acquires a sound source signal from the sound source device 50 . For example, the acquisition unit 21 acquires a sound source signal that is a stereo signal. Specifically, the acquisition unit 21 acquires sound source signals output from the two speakers FL and FR, which are two channels. Acquisition unit 21 outputs the acquired sound source signal to separation unit 22 and output control unit 23 .

In the following description, among the sound source signals, which are stereo signals, the sound source signal output (reproduced) from the left channel speaker FL is referred to as the "Lch sound source signal", and the sound source signal output from the right channel speaker FR. The signal may be described as "Rch sound source signal".

The acquisition unit 21 acquires information indicating the state of the vehicle (for example, the running state such as the vehicle speed, the open/closed state of the windows, etc.) output from the various sensors 60, and outputs the acquired information to the output control unit 23.

The separation unit 22 separates and extracts various sound source signals including a predetermined sound source signal that does not require pseudo-reverberation addition processing from the sound source signal. For example, the separation unit 22 can separate and extract an L component sound source signal, an R component sound source signal, a reverberant sound component sound source signal, etc., in addition to the above-described predetermined sound source signal.

The L component sound source signal is a sound source signal including a sound component (L component) reproduced by one channel (speaker FL) of the two channels of speakers FL and FR. The R component sound source signal is a sound source signal including a sound component (R component) reproduced by the other channel (speaker FR). Note that the L component excitation signal is an example of the first excitation signal, and the R component excitation signal is an example of the second excitation signal. A reverberant sound component sound source signal is a sound source signal containing actual reverberant sound components such as early reflections.

In the above description, the separation unit 22 separates and extracts the predetermined sound source signal, the L component sound source signal, the R component sound source signal, and the reverberant sound component sound source signal from the sound source signal. A configuration may be used in which a portion of the sound source signal is separated and extracted. Further, since the predetermined sound source signal includes an audio component as described above, the predetermined sound source signal may be referred to as an "audio sound source signal" below.

Here, the separation/extraction processing by the separation unit 22 will be described with reference to FIG. FIG. 3 is a diagram for explaining separation/extraction processing by the separation unit 22. As shown in FIG. As shown in FIG. 3 , the separation unit 22 first receives the Lch excitation signal and the Rch excitation signal from the acquisition unit 21 .

Next, the separation unit 22 performs time-frequency analysis on the Lch excitation signal and the Rch excitation signal, respectively, and calculates Lch excitation data and Rch excitation data. For example, the separation unit 22 performs a short-time Fourier transform on the Lch excitation signal to convert it from the time domain to the time-frequency domain, thereby calculating Lch excitation data. Similarly, the separating unit 22 calculates Rch excitation data by performing a short-time Fourier transform on the Rch excitation signal.

The Lch voicing data and the Rch voicing data indicate frequency characteristics of corresponding acoustic signals with respect to time. Specifically, the Lch sound source data and the Rch sound source data are data in which an acoustic signal is divided into predetermined frequency bands and elapsed times, and a relative decibel value (not shown) is set for each divided region. be.

In this manner, the separation unit 22 can accurately calculate the Lch excitation data and the Rch excitation data by performing time-frequency analysis on the excitation signal. In this embodiment, by using the sound source data calculated with high accuracy, it is possible to perform appropriate surround sound reproduction according to the sound source signal.

Next, the separation unit 22 calculates difference information between the Lch excitation data and the Rch excitation data. The difference information is, for example, information indicating the LR channel difference obtained by subtracting the Lch voicing source data from the Rch voicing source data, and is specifically level difference information and phase difference information. Specifically, the level (amplitude) difference information is an inter-channel level difference (ICLD), and the phase difference information is an inter-channel phase difference (ICPD).

In this way, the separation unit 22 calculates difference information indicating the difference between the sound source signals respectively reproduced by the two channels (speakers FL and FR), and uses the difference information to generate an audio sound source as described later. It is possible to accurately separate signals and the like.

Next, the separation unit 22 generates masks for separating and extracting various sound source signals based on the difference information. Specifically, the separating unit 22 generates masks for separating and extracting the speech sound source signal, the L component sound source signal, the R component sound source signal, the reverberant sound component sound source signal, and the like based on the difference information. As the mask, for example, a binary mask that takes only binary values of 0 or 1 can be used, but it is not limited to this.

Also, hereinafter, a mask for separating/extracting an audio source signal may be referred to as an "audio mask". Masks for separating and extracting the L component sound source signal, the R component sound source signal, and the reverberant sound component sound source signal are described as "L component mask," "R component mask," and "reverberant sound mask," respectively. Sometimes.

First, the generation of the "voice mask" will be described. Since voice (vocal) is normally recorded in monaural, it is assumed here that the Lch sound source signal and the Rch sound source signal include the same sound source signal.

The separating unit 22 sets the value of the audio mask (more precisely, the value in each region) based on ICLD, which is level difference information, ICPD, which is phase difference information, and setting condition 1 below. , to generate a mask for the audio.

[Setting condition 1]
Mask value 1: Area where |ICLD|<threshold a and |ICPD|<threshold b Mask value 0: Area other than the above Here, threshold a and threshold b are both set to relatively small values. . Specifically, the threshold a and the threshold b are set to values that allow estimation that both ICLD and ICPD are 0 or near 0, but are not limited to this and can be set to arbitrary values. be.

As described above, since the same sound source signal is included in the Lch sound source signal and the Rch sound source signal, the sound mask is set to the region including the sound source signal (in other words, both ICLD and ICPD) according to setting condition 1. 0 or near 0) is set to 1, and other areas are set to 0.

Next, the separation unit 22 separates and extracts the audio source signal using the generated audio mask. Specifically, the separation unit 22 separates and extracts the audio source signal from the time-frequency domain in which the value of the audio mask is set to 1.

For example, the separating unit 22 applies an audio mask to the Lch excitation data and the Rch excitation data and filters them, thereby separating the audio excitation signal from the Lch excitation data and the Rch excitation data. Then, the separating unit 22 averages the separated two audio source signals and extracts the averaged signal as an audio source signal.

Although an example in which the audio mask is applied to both the Lch sound source data and the Rch sound source data has been described above, the present invention is not limited to this. , an audio source signal may be separated and extracted from one of the data.

In the above description, in the audio mask, the value of the area other than the area where ICLD and ICPD are 0 or near 0 is set to 0, but in addition or instead of this, for example, the audio band 300 to 3400 Hz) may be set to 0 in advance. That is, here, a process of separating and extracting the sound source signal is performed. For this reason, as described above, by setting the value of the frequency region other than the voice band, in other words, the value of the frequency region in which the sound source signal cannot exist, to 0 in advance, the frequency region in which the sound source signal cannot exist can be obtained. It is possible to accurately separate and extract the audio source signal without erroneously detecting the presence of the audio source signal.

Also, in the voice mask, for example, the value of the frequency region below the voice band may be set to 1 in advance. This makes it possible to separate and extract sound source signals of musical instruments that include monaural components and whose frequencies are below the voice band (for example, bass drums).

Next, generation of the “L component mask” will be described. For example, there are cases where more components of a certain musical instrument sound (eg, a piano) are included in the Lch tone generator signal than in the Rch tone generator signal. The L component mask is a mask for separating/extracting such an instrumental sound component as an L component sound source signal.

Specifically, the separating unit 22 determines the value of the L component mask (more precisely, the value in each region) based on ICLD as level difference information, ICPD as phase difference information, and setting condition 2 below. set and generate a mask for the L component.

[Setting condition 2]
Mask value 1: Area where ICLD<threshold c and ICPD<threshold d Mask value 0: Area other than the above Here, threshold c and threshold d are both set to a value of 0 or less. Specifically, the threshold c and the threshold d are set to values that allow estimation that both ICLD and ICPD are negative values, but are not limited to this and can be set to arbitrary values.

That is, since the Lch sound source signal contains many components of a certain musical instrument sound (here, a piano) as described above, the difference information obtained by subtracting the Lch sound source data from the Rch sound source data does not include the certain musical instrument sound component. The ICLD and ICPD of the containing region will be negative. Therefore, under setting condition 2, the L component mask has a value of 1 in a region containing a component of a musical instrument sound (in this case, a piano) (in other words, a region in which both ICLD and ICPD are negative values), and The area will be set to 0.

Next, the separation unit 22 separates and extracts the L component excitation signal using the generated L component mask. Specifically, the separation unit 22 separates and extracts the L component excitation signal from the time-frequency domain in which the value of the L component mask is set to 1. For example, the separating unit 22 separates the L component excitation signal from the Lch excitation data by filtering the Lch excitation data by applying the L component mask.

Next, generation of the “R component mask” will be described. For example, there are cases where more components of a certain musical instrument sound (guitar as an example) are included in the Rch sound source signal than in the Lch sound source signal. The R component mask is a mask for separating/extracting such an instrumental sound component as an R component sound source signal.

Specifically, the separating unit 22 determines the value of the R component mask (more precisely, the value in each region) based on ICLD as level difference information, ICPD as phase difference information, and setting condition 3 below. set and generate a mask for the R component.

[Setting condition 3]
Mask value 1: Area where ICLD>threshold value e and ICPD>threshold value f Mask value 0: Area other than the above Here, both the threshold value e and the threshold value f are set to a value of 0 or more. Specifically, the threshold e and the threshold f are set to values that allow estimation that both ICLD and ICPD are positive values, but are not limited to this and can be set to arbitrary values.

That is, since the Rch sound source signal contains many components of a certain musical instrument sound (guitar in this case) as described above, the difference information obtained by subtracting the Lch sound source data from the Rch sound source data does not include the certain musical instrument sound component. ICLD and ICPD of the containing region are positive. Therefore, according to the setting condition 3, the R component mask has a value of 1 in a region containing a component of a musical instrument sound (here, a guitar) (in other words, a region in which both ICLD and ICPD are positive values), and The area will be set to 0.

Next, the separation unit 22 separates and extracts the R component excitation signal using the generated R component mask. Specifically, the separation unit 22 separates and extracts the R component excitation signal from the time-frequency domain in which the value of the R component mask is set to 1. For example, the separating unit 22 separates the R-component excitation signal from the R-channel excitation data by filtering the R-channel excitation data by applying an R-component mask.

Next, the “reverberation mask” will be described. For example, the Lch sound source signal and the Rch sound source signal may include actual reverberant sound components such as early reflected sound in addition to the monaural component such as the above-described voice, L component, and R component. Some of such reverberant sound components tend to make the sound image unclear during reproduction, and the reverberant sound mask is a mask for separating and extracting such reverberant sound components as reverberant sound component sound source signals.

Specifically, the separation unit 22 determines the value of the reverberation mask (more precisely, the value in each region) based on ICLD as level difference information, ICPD as phase difference information, and setting condition 4 below. set and generate a mask for reverberation.

[Setting condition 4]
Mask value 0: Area where |ICLD|<threshold a and |ICPD|<threshold b Mask value 0: Area where ICLD<threshold c and ICPD<threshold d Mask value 0: ICLD>threshold e, and area where ICPD>threshold value f mask value 1: area other than the above is set to 0, and the value of other areas is set to 1. That is, for example, a region where ICLD and ICPD are reversed in positive and negative or a region where ICPD ≈ 180° is a region containing reverberant sound that tends to make the sound image unclear during reproduction. It will be set to 1.

Next, the separation unit 22 separates and extracts the reverberant sound component sound source signal using the generated reverberant sound mask. Specifically, the separating unit 22 separates and extracts the reverberant sound component sound source signal from the time-frequency domain in which the value of the reverberant sound mask is set to 1.

For example, the separating unit 22 separates reverberant sound component sound source signals from the Lch sound source data and the Rch sound source data by filtering the Lch sound source data and the Rch sound source data by applying reverberant sound masks. Then, the separation unit 22 averages the two separated reverberant sound component sound source signals and extracts the averaged signal as a reverberant sound component sound source signal.

Although an example in which the reverberation mask is applied to both the Lch sound source data and the Rch sound source data has been described above, the present invention is not limited to this. and a reverberant sound component sound source signal may be separated and extracted from one of the data.

In the above description, since the value of each mask is set to 1 or 0, separation distortion may occur in the separation processing of each sound source signal. You may try to reduce the distortion. Also, for regions where the value of each mask is set to 0, a relaxed value such as 0.1 may be set to reduce the separation distortion.

Continuing with the description of FIG. 2 , the separation unit 22 outputs the separated/extracted speech sound source signal, L component sound source signal, R component sound source signal, and reverberant sound component sound source signal to the output control unit 23 . The separation unit 22 also removes the sound source signal (predetermined sound source signal) from the sound source signal to generate a removed sound source signal, and outputs the generated removed sound source signal to the output control unit 23 .

The output control unit 23 controls the sound source signal input from the acquisition unit 21, the speech sound source signal input from the separation unit 22, the L component sound source signal, the R component sound source signal, the reverberant sound component sound source signal, and the removed sound source signal. , and output from the speakers FL, FR, RL, and RR.

For example, the output control unit 23 D/A converts a sound source signal including direct sound or the like, amplifies the D/A converted sound source signal, and outputs (reproduces) it from the speakers FL and FR. Here, the sound image of reproduced sound will be described with reference to FIGS. 4A to 4G.

4A to 4G are diagrams for explaining a sound image of sound reproduced by the output control section 23. FIG. Note that FIG. 4A shows a state in which only a sound source signal including direct sound or the like is output and reproduced, in other words, a state in which pseudo-reverberant sound or the like is not reproduced (added). 4A to 4F, the sound image of voice (vocal) is indicated by symbol A1. Also, the sound source signal is a stereo signal as described above, and includes an Lch sound source signal and an Rch sound source signal. In FIGS. 4A to 4F, the symbol AL denotes a sound image such as a musical instrument sound that is included more in the Lch sound source signal than in the Rch sound source signal. A sound image such as that shown in FIG.

As shown in FIG. 4A, when the output control unit 23 outputs sound source signals including direct sounds and the like from the speakers FL and FR, the sound image A1 of the voice and the sound images AL and AR of the musical instrument sound are relatively different between the speakers FL and FR. Localized at narrow intervals.

Continuing the description of FIG. 2, the output control unit 23 has a filter 23a, and uses the filter 23a to generate and output a pseudo-reverberation sound. The filter 23a is a filter for generating pseudo-reverberant sound. As the filter, for example, an FIR filter, an IIR filter, or the like can be used, but the filter is not limited to this.

For example, the output control unit 23 applies the filter 23a to the sound source signal from which the predetermined sound source signal has been removed, ie, the removed sound source signal, to generate a reverberation signal representing a pseudo-reverberation sound. The output control unit 23 D/A converts the reverberation signal, amplifies the D/A converted reverberation signal, and outputs the amplified reverberation signal from the speakers RL and RR. As a result, the pseudo-reverberation sound is added to the direct sound or the like.

Therefore, as shown in FIG. 4B, for example, the output control unit 23 adjusts the volume of the pseudo-reverberant sound output from the speakers RL and RR, and localizes the sound image B of the pseudo-reverberant sound around the listener L. Thus, the listener L can feel a sufficient wrapped feeling LEV.

As described above, the output control unit 23 according to the present embodiment applies the filter 23a only to the sound source signal (removed sound source signal) from which the sound source signal that does not require the addition processing of the pseudo reverberation is removed, and generates the reverberation signal. and output.

As a result, even if the sound source signal includes, for example, a sound source signal that requires pseudo-reverberation addition processing and an unnecessary sound source signal (here, a speech sound source signal), the sound source signal that requires addition processing can Since the reverberation signal is generated and output only for the sound source signal, appropriate surround sound reproduction corresponding to the sound source signal (more specifically, according to the content (type) of the sound source signal) can be performed.

In the above description, the output control unit 23 applies the filter 23a only to the sound source signal from which the sound source signal has been removed (removed sound source signal), but the present invention is not limited to this. That is, for example, the output control unit 23 may apply the filter 23a to both the sound source signal from which the sound source signal (predetermined sound source signal) has been removed and the sound source signal. At this time, the output control unit 23 controls the reverberation level of the pseudo reverberation sound corresponding to the sound source signal from which the sound source signal has been removed (removed sound source signal) to be higher than the reverberation level of the pseudo reverberation sound corresponding to the sound source signal. output as Conversely, the output control unit 23 outputs the pseudo-reverberant sound corresponding to the audio source signal so that the reverberation level is lower than the reverberation level of the pseudo-reverberant sound corresponding to the removed sound source signal. In other words, the filter 23a is set to generate a reverberation signal having the reverberation level of the pseudo-reverberation sound described above.

As a result, it is possible to prevent the listener L from having an unnatural impression that the sound image or timbre of the voice (vocal) is extremely clear and stands out in front of the listener L, for example. Specifically, for example, for a musical sound source signal in which vocals and instrumental sounds are mixed, large reverberation is applied only to the sound source signal of the instrumental sound (that is, the removed sound source signal), and no reverberation is applied to the vocal sound source signal. In this case, the listener L may be given an unnatural impression that the sound image and timbre of only the vocal are extremely clear and stand out in front of the listener. This is because there is a psychological characteristic of feeling the sound image (here, the sound image of an instrument) farther away when there is a lot of reflected sound due to strong reverberation, and along with this, the impression that the sound image without any reverberation (here, the vocal sound image) approaches the foreground. It is caused by becoming Therefore, by applying the filter 23a to both the sound source signal from which the sound source signal has been removed and the sound source signal, and varying the reverberation levels as described above, the unnatural impression described above can be reduced to the listener L. It becomes possible to suppress giving to

Note that the output control unit 23 may select a speaker for outputting the removed sound source signal for surround reproduction from among the speakers FL, FR, RL, and RR according to the content (type) of the removed sound source signal. As an example, the output control unit 23 selects the speakers that output the sound source signal and the reverberation signal so that the direct sound and the pseudo-reverberation sound are reproduced with the listener L sandwiched therebetween, thereby reducing the enveloping feeling LEV. It may be improved.

Specifically, the reverberation signal (in other words, the removed sound source signal that is reproduced in surround sound by applying the filter 23a) includes the L component sound source signal and the R component sound source signal, and the L component sound source signal and the R component sound source signal. The component sound source signals are separated and extracted by the separating section 22 . Therefore, of the reverberation signal (the removed sound source signal to which the filter 23a is applied), the output control unit 23 surround-plays (outputs) the L component sound source signal from the speaker RR, and surround-plays the R component sound source signal from the speaker RL. .

As a result, the listener L can move between the speaker FL that reproduces the L component of the direct sound and the speaker RR that reproduces the L component of the pseudo-reverberant sound in surround sound, and the speaker FR that reproduces the R component of the direct sound. and the speaker RL through which the R component of the pseudo-reverberation sound is reproduced in surround sound. Therefore, the pseudo-reverberant sound image B is easily localized around the listener L, and as a result, the enveloping feeling LEV for the listener L can be improved.

The output control unit 23 also applies the filter 23a to the separated reverberant sound component sound source signal to generate a reverberation signal. Then, the output control unit 23 may output the reverberation signal generated from the reverberation sound component sound source signal from the speakers RL and RR. As a result, the pseudo-reverberant sound generated by the reverberant component sound source signal is added to the direct sound or the like. Specifically, for example, among the actual reverberant sound components, the pseudo-reverberant sound of the reverberant sound component whose sound image tends to be unclear during reproduction is added to the direct sound, thereby clarifying the sound image of the reverberant sound component, and It is possible to further improve the wrapped feeling LEV.

By the way, for example, in a passenger compartment of a vehicle, another listener Lx may be seated behind the passenger compartment (for example, in the rear seat) as indicated by the imaginary line in FIG. 4B. At this time, if the pseudo-reverberating sound adding process described above is performed, the reverberant sound including the pseudo-reverberating sound may become excessive for the listener Lx.

Therefore, the output control unit 23 according to the present embodiment may suppress excessive reverberation for the listener Lx by performing pseudo reverberation addition processing according to the state of the vehicle. Specifically, the output control unit 23 applies the filter 23a to the removed sound source signal according to the state of the vehicle, and transmits the applied removed sound source signal (that is, the reverberation signal) to a channel (for example, speakers RL, RR, etc.). Excessive reverberation may be suppressed by outputting from .

For example, as shown by the imaginary line in FIG. 4B, when the vehicle is in a state where the speaker Rx exists behind the listener Lx in the back seat, the output control unit 23 outputs the removed sound source signal to which the filter 23a is applied. (reverberation signal) is output from the speaker Rx. As a result, although illustration is omitted, it is possible to localize the sound image of the pseudo-reverberant sound around the listener Lx. Therefore, even for the listener Lx, the wrapped feeling LEV can be secured similarly to the listener L, and excessive reverberation can be suppressed.

Further, for example, the output control unit 23 may perform pseudo-reverberation addition processing according to fader adjustment instructions (an example of the state of the vehicle) for the speakers FL, FR, RL, and RR. For example, the output control unit 23 weakens the reverberation signals output from the speakers RL and RR or adjusts the reverberation signals when the various sensors 60 detect, as the state of the vehicle, a fader adjustment instruction indicating that reproduction is to be performed with emphasis placed on the rear seats. may be prohibited. As a result, the pseudo-reverberant sound is reduced or eliminated, so that excessive reverberant sound for the listener Lx can be suppressed.

Further, for example, the output control unit 23 may perform pseudo-reverberation sound addition processing according to the seated state of the passenger (an example of the state of the vehicle). For example, the output control unit 23 outputs the reverberation signal when the various sensors 60 detect that the passenger is not seated in the rear seat, that is, that the listener Lx is not present, as the state of the vehicle. may be output from the speakers RL and RR. As a result, excessive reverberation as described above does not occur.

Further, for example, the output control unit 23 performs processing for adding a pseudo-reverberation sound in accordance with at least one of the conditions of the vehicle, such as an open/closed state of the windows in the vehicle, an operating state of the air conditioner, and a running state such as the vehicle speed. good too. For example, when the windows of the rear seats are open, when the air conditioner is operated with a relatively strong wind, when the vehicle is traveling at a relatively high speed, etc., relatively loud noise is generated in the rear seats. Therefore, it is presumed that the listener Lx in the rear seat is in an environment in which it is difficult for the listener Lx to perceive the above-described reverberant sound. Therefore, the output control unit 23 outputs reverberation signals from the speakers RL and RR when the various sensors 60 detect the state of the vehicle, such as opening the window, operating the air conditioner in a strong wind, or running at high speed. good too. As a result, since the listener Lx is in an environment in which it is difficult for the listener Lx to perceive the reverberant sound, it is possible to suppress excessive reverberant sound for the listener Lx.

In the above description, the reverberation signals are output from the speakers RL and RR arranged behind the listener L, but the present invention is not limited to this. It may be configured to output from another speaker such as a speaker (not shown).

In addition, the output control unit 23 can perform localization control of a sound image. Specifically, the output control unit 23 can output the audio source signal so that the sound image A1 of the audio generated by the separated audio source signal is localized at a predetermined position. For example, as shown in FIG. 4C, the output control unit 23 emphasizes and outputs the separated sound source signals from the speakers RL and RR, so that the sound image A1 of the sound (vocal) from the sound source signals is output to the listener L. It can be localized to a position displaced to the side. As a result, for example, the sound image A1 of the voice and the sound images AL and AR of the musical instrument sound can be made difficult to overlap, so that the sounds corresponding to the sound images A1, AL and AR can be clarified. In addition, "emphasis" in this specification means, for example, adding and reproducing sounds corresponding to various signals, or increasing the volume of the reproduced sounds, but is limited to this. not a thing

In the above description, the predetermined position is displaced toward the listener L side, but the present invention is not limited to this, and can be set to any position. For example, although not shown, a speaker is placed above the listener L, and the sound source signal is emphasized and output from the speaker, thereby localizing the sound image A1 of the sound upward. You can let it run. As a result, the sound image A1 and the sound images AL and AR are displaced in the height direction, so that, for example, the three-dimensional effect of the sound can be increased to improve the sense of reality.

Further, the output control unit 23 may emphasize and output the separated sound source signal from the speakers FL, FR, for example. As a result, the voice of the voice source signal emphasized is added to the voice (vocal) included in the direct sound, thereby making it possible to further clarify the sound image A1 of the voice.

In addition, the output control unit 23 can perform sound image width control of the sound image. Specifically, as shown in FIG. 4D, the output control unit 23 outputs the separated L component sound source signal from one speaker (channel) FL, and controls the sound image width of the L component sound source signal. good too. For example, the output control unit 23 emphasizes and outputs the separated L component sound source signal from the speaker FL. As a result, the instrumental sound (for example, piano), which is an example of the L component included in the direct sound, is added to the instrumental sound of the emphasized L component sound source signal. It is possible to expand.

Similarly, the output control unit 23 may output the separated R component sound source signal from the other speaker (channel) FR and control the sound image width of the sound by the R component sound source signal. For example, the output control unit 23 emphasizes and outputs the separated R component sound source signal from the speaker FR. As a result, an instrumental sound (for example, a guitar), which is an example of the R component included in the direct sound, is added with the instrumental sound of the enhanced R component sound source signal. It is possible to expand.

4D, the output control unit 23 outputs the separated L component sound source signal from the speaker RL, and the sound image width ALx of the sound (instrument sound in this case) by the L component sound source signal. may be controlled to expand backward. Similarly, the output control unit 23 outputs the separated R component sound source signal from the speaker RR, and controls to expand the sound image width of the sound image ARx of the sound (instrument sound in this case) caused by the R component sound source signal to the rear. may As a result, the sound images ALx and ARx can be localized at positions where the listener L is wrapped.

Here, for example, noise (running noise) such as running noise and air conditioner noise is generated in the vehicle interior. In addition, in the example of FIG. 4E, the sound image of noise is indicated by symbol C. As shown in FIG. A sound image C of noise may be localized near the listener L in some cases. In this case, since the sound image C of the noise is close to or overlaps with the sound image A1 of the voice and the sound images AL and AR of the musical instrument sounds, the noise is mixed with the voice and music, and the sound images A1, AL and AR are unclear. was likely to become

Therefore, for example, the output control unit 23 emphasizes and outputs the separated sound source signals from the speakers FL and FR, weakens the sound source signals that have been emphasized and output from the speakers RL and RR, or prohibits output. By doing so, the sound image A1 of the sound generated by the sound source signal is localized at a position displaced in a direction away from the noise sound image C (for example, forward) (see arrow D1). As a result, for example, the sound image A1 of the sound and the sound image C of the noise can be made difficult to overlap, in other words, it is possible to make it difficult for the noise to mix with the sound, and the sound image A1 of the sound can be clarified.

Further, for example, the output control unit 23 emphasizes and outputs the separated L component sound source signal from the speaker FL, weakens the L component sound source signal that has been emphasized and output from the speaker RL, or prohibits output. . As a result, the output control unit 23 localizes the sound image AL of the instrumental sound of the L-component sound source signal to a position displaced in a direction away from the sound image C of the noise (for example, forward) (see arrow D2a). The width is expanded to the left (see arrow D2b). As a result, for example, the sound image AL of the instrumental sound and the sound image C of the noise can be made difficult to overlap, in other words, it is possible to make it difficult for the noise to mix with the instrumental sound, thereby clarifying the sound image AL of the instrumental sound. can be done.

Similarly, for example, the output control unit 23 emphasizes and outputs the separated R component sound source signal from the speaker FR, weakens the R component sound source signal that has been emphasized and output from the speaker RR, or prohibits output. do. As a result, the output control unit 23 localizes the sound image AR of the instrumental sound of the R component sound source signal to a position displaced away from the noise sound image C (see arrow D3a), or shifts the sound image width of the sound image AR to the right. (see arrow D3b). As a result, for example, the sound image AR of the instrumental sound and the sound image C of the noise can be made difficult to overlap, in other words, it is possible to make it difficult for the noise to mix with the instrumental sound, and the sound image AR of the instrumental sound can be clarified. can be done.

Note that the output control unit 23 may perform localization control and sound image width control of the sound images A1, AL, and AR according to the position of the sound image C of noise. That is, for example, the position of the sound image C of the noise changes according to the running state such as the vehicle speed, the open/closed state of the windows, the operating state of the air conditioner, and the like. Therefore, for example, the correlation between the driving state, the window opening/closing state, the operating state of the air conditioner, and the position of the sound image C of the noise is calculated in advance through experiments or the like, and the output control unit 23 indicates the calculated correlation. Localization control and sound image width control of the sound images A1, AL, and AR may be performed based on the information. The position of the sound image C of the noise may be detected by analyzing the sound collected using a microphone (not shown) or the like.

Here, for example, a vehicle may be configured to be able to run by automatic driving control that does not require driving operation by a passenger (driver). When such automatic driving control is executed, the driving load on the listener L, who is a passenger, is reduced. Therefore, as shown in FIG. be. Note that the video 31 can be set to any type of video, but here includes a video of a musical instrument being played corresponding to the instrumental sound contained in the sound source signal, and a video of a singer emitting voice (vocal). shall be

In this way, when the vehicle is in a state where the automatic driving control is executed and the image 31 is displayed, the output control unit 23 performs localization control and sound image width control of the sound images A1, AL, and AR according to the image 31. good too. For example, the output control unit 23 emphasizes and outputs the separated audio source signal from the speakers FL and FR, and localizes the sound image A1 of the audio by the audio source signal to a position overlapping the image 31 . Further, for example, the output control unit 23 emphasizes and outputs the separated L component sound source signal from the speaker FL or the speaker RL, so that the sound image AL of the instrumental sound of the L component sound source signal overlaps with the image 31. It localizes to a position and controls the sound image width of the sound image AL. Similarly, the output control unit 23 emphasizes and outputs the separated R component sound source signal from the speaker FR and the speaker RR, so that the sound image AR of the instrumental sound of the R component sound source signal overlaps with the image 31. or control the sound image width of the sound image AR. As a result, the sound images A1, AL, and AR are superimposed on the image 31 of the singer and the musical instrument, so that the listener L can feel the expansion of the sound images A1, AL, and AR in line with the image 31. FIG.

Also, as shown in FIG. 4G, for example, when the automatic driving control is executed or when the vehicle is parked, the direction of the seat of the listener L who is a passenger may be changed. In such a case, the output control unit 23 may perform localization control and sound image width control of the sound images A1, AL, and AR according to the orientation of the seat (or the orientation of the face of the listener L). For example, the output control unit 23 emphasizes and outputs the separated audio source signal from a speaker selected according to the orientation of the seat from among the speakers FL, FR, RL, and RR, and outputs the separated audio source signal. The sound image A1 of the voice is localized at a position in front of the listener L. Further, for example, the output control unit 23 emphasizes and outputs the separated L component sound source signal from a speaker selected according to the orientation of the seat, thereby producing a sound image AL of the instrument sound of the L component sound source signal. It localizes the sound to the left of the listener L and controls the sound image width of the sound image AL. Similarly, the output control unit 23 emphasizes and outputs the separated R component sound source signal from a speaker selected according to the orientation of the seat, and listens to the sound image AR of the instrument sound of the R component sound source signal. It localizes the sound to the right of the person L and controls the sound image width of the sound image AR. This makes it possible to localize (arrange) the sound images A1, AL, and AR at positions that match the state of the vehicle including the direction of the seat (in other words, the direction of the listener L). Although the direction of the face of the listener L is detected by an in-vehicle camera (not shown) or the like, it is not limited to this.

In the above description, localization control of the sound images A1, AL, and AR is performed according to the orientation of the seat and the orientation of the listener L's face. ), etc., localization control may be performed. Further, in the localization control, etc., the sound images A1, AL, AR can be clarified by preventing the sound images A1, AL, AR from overlapping with the noise sound image C, as shown in FIG. 4G.

Continuing the description of FIG. 2, for example, voices included in the sound source signal may include vocals and voice guidance in navigation and the like. In such a case, the voice guidance may overlap with the vocal, making it difficult for the listener L to hear the voice guidance.

Therefore, for example, the output control unit 23 outputs the sound source signal (removed sound source signal) from which the sound source signal including the vocal is removed and the sound source signal including the voice guidance as direct sounds from the speakers FL and FR. As a result, although not shown, the sound images AL and AR of the musical instrument sounds and the sound image of the voice guidance are localized in the passenger compartment. Therefore, the voice guidance does not overlap the vocal, so that the listener L can easily hear the voice guidance. At this time, the output control unit 23 can also provide voice guidance without lowering the audio volume.

<Control processing of the audio device according to the first embodiment>
Next, a specific processing procedure in the audio device 1 will be described with reference to FIG. FIG. 5 is a flow chart showing a processing procedure executed by the acoustic device 1 according to the first embodiment.

As shown in FIG. 5, the control unit 2 of the acoustic device 1 acquires a sound source signal from the sound source device 50 (step S10). Next, the control unit 2 separates the speech sound source signal, the L component sound source signal, the R component sound source signal, and the reverberant sound component sound source signal from the sound source signal (step S11).

Next, the control unit 2 removes the sound source signal from the sound source signal, applies the filter 23a to the sound source signal from which the sound source signal has been removed, and the reverberant sound component sound source signal, respectively, to generate a reverberation sound signal (step S12).

Next, the control unit 2 controls output of the sound source signal, the separated sound source signal, the L component sound source signal, the R component sound source signal, and the generated reverberation sound signal (step S13).

As described above, the acoustic device 1 according to the first embodiment includes the separator 22 and the output controller 23 . The separation unit 22 separates a predetermined sound source signal (speech sound source signal) that does not require processing to add a pseudo pseudo-reverberation sound from the sound source signal, and removes the separated predetermined sound source signal from the sound source signal. The output control unit 23 applies a filter 23a for generating a pseudo-reverberation sound to the sound source signal from which the predetermined sound source signal has been removed by the separation unit 22, and outputs the result. As a result, appropriate surround reproduction can be performed according to the sound source signal.

In addition, since the separation unit 22 uses time-frequency analysis, it is possible to separate various sound source signals such as speech sound source signals with a relatively low amount of calculation. In addition, in the present embodiment, sound image localization control, sound image width control, optimization of feeling of envelopment LEV, etc. are performed for each of various sound source signals such as separated sound source signals. It is possible to improve the overall spatial impression of the sounds reproduced from RL and RR.

Further, in this embodiment, the filter 23a is used in combination with the process of separating various sound source signals such as the voice sound source signal from the sound source signal. As a result, the filter length of the filter 23a can be shortened compared to the case where only the filter 23a is used, for example, so that the amount of calculation in the control section 2 can be reduced.

Further, for example, if the sound source signal contains an instrumental sound such as a percussion instrument with a short duration, the frequency characteristics may include a dominant component whose level protrudes near a predetermined frequency. If such a dominant component exists, the reverberant sound including the pseudo-reverberant sound tends to be excessive during surround reproduction. Also, the higher the frequency, the easier it is for the reverberant sound to separate, and the reverberant sound tends to be excessive. Therefore, for example, the control unit 2 can reduce the influence of the above-described dominant component by performing processing to make the frequency characteristic such that the higher the frequency is linearly or smoothly attenuated. Even with a sound source signal that includes instrumental sounds, excessive reverberation can be suppressed.

In addition, when outputting reverberation signals to the speakers FR, FL, RL, and RR (surround channels), the control unit 2 adds a random delay, or controls the time characteristics such as the rising edge of the filter 23a to have randomness. The cross-correlation may be lowered. This allows the listener L to perceive the pseudo-reverberant sound as more natural reverberant sound.

(Second embodiment)
<Structure of Acoustic Device According to Second Embodiment>
Next, the configuration of the acoustic device 1 according to the second embodiment will be described with reference to FIG. FIG. 6 is a block diagram showing a configuration example of an audio system 100 including the audio device 1 according to the second embodiment. In addition, below, about the structure common to 1st Embodiment, the same code|symbol is attached|subjected and description is abbreviate|omitted.

The control unit 2 of the acoustic device 1 according to the second embodiment includes a filter setting unit 24 that sets the gain of the filter 23a that generates the pseudo reverberation sound. In the second embodiment, the filter setting unit 24 changes the gain of the filter 23a for each sound source (instrument or voice), thereby outputting a more natural pseudo-reverberation sound in the sound source signal of one piece of music. Specifically, in the second embodiment, the filter setting unit 24 sets a filter whose gain is optimized for each sound source based on the characteristics of each sound source included in the sound source signal, thereby achieving high-quality surround sound. Regeneration can be realized.

Specifically, the acquisition unit 21 of the control unit 2 acquires sound source information about the sound source signal. The sound source information is, for example, the type (genre) of the sound source signal and information about the recording environment, but is not limited to this. The types of sound source signals are, for example, voice, musical instruments (percussion instruments, wind instruments, etc.), classical music, and the like. The recording environment is, for example, information about the recording location such as a recording studio or a concert hall.

For example, the acquisition unit 21 acquires sound source information through input by a user such as the listener L, or acquires sound source information from a server or the like via the Internet. Further, the acquisition unit 21 may acquire sound source information by analyzing the acquired sound source signal. The acquisition unit 21 outputs the acquired sound source information to the filter setting unit 24 .

The filter setting unit 24 includes a detection unit 24a and a determination unit 24b. Based on the sound source signal, the detection unit 24a detects feature information that is a feature of an acoustic component included in the sound source signal.

For example, the detection unit 24a detects channel relationship information relating to the relationship between the sound source signals reproduced on each of the two channels as the feature information relating to the features of the acoustic component. Specifically, the channel-related information includes LR channel difference and LR channel correlation information.

The LR channel difference is the above-described inter-channel level difference (ICLD) or inter-channel time difference (Inter-channel Time Difference), but is not limited to these. LR channel correlation is information about correlation components of two sound source signals that are stereo-reproduced in two channels. Specifically, the LR channel correlation is inter-channel cross correlation (ICC), but is not limited to this.

In this way, the detection unit 24a can detect the acoustic component with high accuracy by detecting the channel-related information as the feature information, so that the output control unit 23 performs filtering to generate an optimal pseudo-reverberation sound. can do.

Then, the detection unit 24a continuously detects the channel-related information at regular intervals, arranges them in time series, and calculates a moving average of the detected time-series channel-related information, thereby detecting the moving average as feature information. do. As a result, a sharp change in the channel-related information can be smoothed, and a sharp change in the gain determined by the determination unit 24b in the subsequent stage can be smoothed. As a result, changes in the pseudo reverberation generated by the output control unit 23 can be smoothed, so that more natural surround reproduction can be achieved.

Note that the detection unit 24a maximizes the channel-related information in the time-series channel-related information, and then performs moving average for the interval in which the sound pressure level (amplitude) of the sound source signal is less than a predetermined value. In other words, the detecting unit 24a moves so as not to output surround sound in the section where the sound pressure level of the sound source signal is less than a predetermined value in the time-series channel-related information, and to control in a direction not to output surround sound around the section in which the sound pressure level is less than the predetermined value. Calculate the average.

This lowers the upper limit at which the law of the first wave front holds when there is silence between strikes, such as when performing a solo percussion instrument. be.

The detection unit 24a also detects information about the duration and frequency of the acoustic component as feature information. Duration time is the duration of the sound source signal. Specifically, the detection unit 24a calculates the envelope of the sound source signal, differentiates the calculated envelope, calculates the envelope again, and detects the duration from the slope of the obtained envelope. Frequency is information about the frequency component of the sound source signal. Specifically, the detection unit 24a detects the center of gravity of the frequency of the sound source signal in the sound source data obtained by performing a short-time Fourier transform on the sound source signal.

In this way, the detection unit 24a can detect the acoustic component with high accuracy by detecting the duration time and frequency information as the characteristic information. A pseudo-reverberant sound can be generated.

The determination unit 24b determines the gain of the filter 23a used by the output control unit 23. FIG. Specifically, the determination unit 24b determines the gain of the filter 23a based on at least one of the feature information detected by the detection unit 24a and the sound source information acquired by the acquisition unit 21. FIG.

Specifically, the determination unit 24b corrects the threshold range obtained from the first wavefront law based on at least one of the feature information and the sound source information, and determines the gain based on the corrected threshold range. Here, gain determination processing based on the law of the first wavefront will be described with reference to FIG.

FIG. 7 is a diagram illustrating gain determination processing by the determination unit 24b. As shown in FIG. 7, the determining unit 24b first corrects the threshold range obtained from the first wavefront law based on feature information (channel related information, duration and frequency) and sound source information.

For example, regions R1 and R2, which are threshold ranges shown in the middle graph of FIG. 7, are set as reference ranges. In such a case, the determination unit 24b corrects the regions R1 and R2 by correcting the threshold TH1 and the threshold TH2 on the two axes of time and amplitude based on the feature information and the sound source information.

For example, the determination unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and amplitude increase as the channel-related information increases. That is, the determination unit 24b corrects the area R1 and the area R2 so that the larger the channel-related information, the larger the area R1 and the area R2.

On the other hand, the determining unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude become smaller as the channel-related information becomes smaller. That is, the determining unit 24b corrects the area R1 and the area R2 so that the smaller the channel-related information, the smaller the area R1 and the area R2.

The channel-related information increases as the inter-channel level difference, which is the channel-related information, increases, as the inter-channel time difference increases, or as the cross-correlation decreases (the number of uncorrelated components increases).

Further, the determining unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude increase as the duration of the acoustic component increases. In other words, the determination unit 24b corrects the region R1 and the region R2 so that the longer the duration of the acoustic component, the larger the region R1 and the region R2.

On the other hand, the determining unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude become smaller as the duration of the acoustic component becomes shorter. In other words, the determining unit 24b corrects the area R1 and the area R2 so that the shorter the duration of the acoustic component, the smaller the area R1 and the area R2.

Further, the determination unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude increase as the frequency (center of gravity) of the acoustic component decreases. In other words, the determining unit 24b corrects the area R1 and the area R2 so that the lower the frequency (center of gravity) of the acoustic component is, the larger the area R1 and the area R2 are.

On the other hand, the determining unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude decrease as the frequency (center of gravity) of the acoustic component increases. In other words, the determining unit 24b corrects the region R1 and the region R2 so that the higher the frequency (center of gravity) of the acoustic component, the smaller the region R1 and the region R2.

Further, when the sound source information indicates that the sound source signal is classical music, the determination unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude increase. That is, when the sound source signal is classical music, the determination unit 24b corrects the area R1 and the area R2 to be larger.

On the other hand, when the sound source information indicates that the sound source signal is voice, the determination unit 24b corrects the threshold TH1 and the threshold TH2 so that the time and the amplitude become smaller. In other words, when the sound source signal is voice, the determining unit 24b corrects the area R1 and the area R2 to be smaller.

Then, the determination unit 24b determines the gain of the filter 23a used in the subsequent output control unit 23 based on the corrected threshold range. Specifically, the determination unit 24b determines the gain so that the pseudo reverberation generated by the filter 23a falls within the corrected threshold range.

In other words, the determination unit 24b determines the gain so that the duration and amplitude of the pseudo-reverberation sound are increased when the region R1 and the region R2 are corrected to be increased. On the other hand, the determining unit 24b determines the gain so that the time and amplitude of the pseudo-reverberant sound are reduced when the region R1 and the region R2 are corrected to be smaller.

In this way, the determination unit 24b determines the gain from the threshold range of the first wavefront law corrected based on the feature information and the sound source information, thereby determining the gain for generating the optimum pseudo-reverberation sound. can be done.

Then, the output control unit 23 uses the filter 23a to which the gain determined by the determination unit 24b is set to generate and output a reverberation signal representing a pseudo-reverberation sound.

As a result, in the second embodiment, even when the characteristics of the reverberant sound of the sound source are different, such as voice, percussion instruments, classical music, etc., it is possible to generate the optimum pseudo-reverberant sound for each sound source, Optimal surround reproduction is possible according to the characteristics of the sound source. That is, in the second embodiment, surround reproduction with high sound quality can be performed.

<Control processing of the audio device according to the second embodiment>
Next, a specific processing procedure in the acoustic device 1 according to the second embodiment will be described using FIG. FIG. 8 is a flow chart showing a processing procedure executed by the audio device 1 according to the second embodiment.

As shown in FIG. 8, the control unit 2 of the audio device 1 performs the same processing as in the first embodiment in steps S10 and S11. Next, the control unit 2 acquires sound source information regarding the sound source signal (step S11a).

Next, based on the acquired sound source signal and sound source information, the control unit 2 detects feature information that is a feature of the acoustic component included in the sound source signal (step S11b). Next, the control unit 2 determines the threshold range in the first wavefront law based on the detected feature information (step S11c).

Next, based on the determined threshold range, the control unit 2 determines the gain of the filter 23a so that the pseudo-reverberation sound falls within the threshold range (step S11d). Then, the control unit 2 executes the processing from step S12 onward using the filter 23a whose gain has been determined and set.

In the above description, time-frequency analysis is performed on the Lch excitation signal and the Rch excitation signal in the process of removing the audio excitation signal from the excitation signal, but the present invention is not limited to this. That is, without performing time-frequency analysis, processing for removing the audio source signal from the source signal may be performed using the difference or ratio between the Lch source signal and the Rch source signal, the LR channel correlation, or the like. You may try to reduce the calculation by

Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments so shown and described. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and equivalents thereof.

1 acoustic device 2 control unit 22 separation unit 23 output control unit 24a detection unit 24b determination unit

Claims (10)

a separation unit that separates a predetermined sound source signal that does not require processing for adding a pseudo-pseudo reverberation sound from a sound source signal, and removes the separated predetermined sound source signal from the sound source signal;
an output control unit that applies a filter for generating the pseudo-reverberation sound to the sound source signal from which the predetermined sound source signal has been removed by the separation unit, and outputs the sound device. The output control unit is
2. The acoustic apparatus according to claim 1, wherein the predetermined sound source signal is output such that a sound image of the sound generated by the predetermined sound source signal separated by the separation unit is localized at a predetermined position. The output control unit is
the sound source signal from which the predetermined sound source signal has been removed, and the reverberation level of the pseudo-reverberation sound corresponding to the sound source signal from which the predetermined sound source signal has been removed by applying the filter to the predetermined sound source signal, 3. The acoustic apparatus according to claim 1, wherein the reverberation level of the pseudo-reverberation sound corresponding to the predetermined sound source signal is higher than that of the pseudo-reverberation sound. The separation unit is
The acoustic device according to any one of claims 1 to 3, wherein time-frequency analysis is performed on the sound source signal to separate the predetermined sound source signal. The sound source signal is
A stereo signal reproduced in stereo on two channels,
The separation unit is
Difference information indicating a difference between the sound source signals respectively reproduced by the two channels is calculated, and the predetermined sound source signal is separated based on the calculated difference information. Acoustic device according to any one of. The sound source signal is
A stereo signal reproduced in stereo on two channels,
The separation unit is
Separating from the sound source signal a first sound source signal containing sound components reproduced in one of the two channels and a second sound source signal containing sound components reproduced in the other channel death,
The output control unit is
The first sound source signal separated by the separation unit is output from one of the channels to control the sound image width of the sound by the first sound source signal, and the second sound source signal is output from the other channel to control the The acoustic device according to any one of claims 1 to 5, wherein the sound image width of the sound by the second sound source signal is controlled. a detection unit that detects feature information indicating features of acoustic components included in the sound source signal based on the sound source signal;
a determination unit that determines a gain of the filter based on the feature information detected by the detection unit;
The output control unit is
The filter according to any one of claims 1 to 6, wherein the filter to which the gain determined by the determination unit is set is used to generate and output a reverberation signal representing the pseudo reverberation sound. sound equipment. further comprising an acquisition unit that acquires the state of the vehicle,
The output control unit is
A channel arranged at least either behind or above a listener by applying the filter to the sound source signal from which the predetermined sound source signal has been removed according to the state of the vehicle acquired by the acquisition unit. 8. The acoustic device according to any one of claims 1 to 7, wherein the output is from. The acoustic device according to any one of claims 1 to 8, wherein the predetermined sound source signal includes a voice component. a separation step of separating a predetermined sound source signal that does not require processing for adding a pseudo-pseudo reverberation sound from a sound source signal, and removing the separated predetermined sound source signal from the sound source signal;
and an output control step of applying a filter for generating the pseudo-reverberation sound to the sound source signal from which the predetermined sound source signal has been removed by the separating step, and outputting the sound control method.

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