JPH07222297A - Sound field reproducing device - Google Patents

Abstract

PURPOSE:To provide the sound image reproducing device for getting a natural distance feeling or a spreading feeling in every direction by using a two-channel speaker or headphone. CONSTITUTION:An audio signal is converted to a digital signal by an A/D converter 2 and outputted to a signal processing means 3. The signal processing means 3 is provided with a direct sound image localization means for directly localizing the input signal in the sound source direction of the sound and a reflected sound image localization means for localizing it in plural reflecting directions. Then, these parameters are controlled so as to provide the desired sound image corresponding to the sound field. The left and right signals of these sound image localization means are respectively added by an adder and outputted from speakers 6-1 and 6-2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field reproducing apparatus for controlling a sound image distance feeling and a sound field spreading feeling for reproducing sound with a realistic sensation in AV (audio / visual) equipment.

[0002]

2. Description of the Related Art In recent years, VTRs have been used in the video and audio fields.
Due to the widespread use of sound, a large screen and realistic sound reproduction are desired in order to enjoy movies at home, and the development of hardware corresponding thereto is desired. Particularly in the sound of VTR movie software, the Dolby Surround system in which speakers are arranged laterally or backward (or a combination thereof) for reproduction is prevalent, as is done in movie theaters.

Separately from this, sound field signal reproduction for home TV sets and the like so that sound can be heard from the side or the rear without actually placing the speaker on the side or the rear. The device is being developed. Also, in sound field reproduction, development is underway to interactively control the sense of distance and the sense of spaciousness.

FIG. 8 is a block diagram showing an example of a conventional sound field reproducing device for performing a sense of distance control. In the figure, a signal input unit 101 is an input unit for inputting an audio signal, and its output is input to the amplifiers 103a and 103b via the gain controller 102. The gain controller 102 is connected with a distance input means 104 for controlling the listener's sense of distance, and changes the signal level of two channels according to the distance. And amplifier 10
The outputs of 3a and 103b are connected to the speakers 105a and 105b.

A conventional conventional sound field reproducing device having such a configuration will be described. The level of the gain controller 102 is controlled so that the signal input by the signal input unit 101 is reproduced from the speakers 105a and 105b at a volume corresponding to the distance input by the distance input unit 104. Generally, when the volume level is high, the distance is short, and when the volume is low, the distance is long. The gain controller 102 performs such control to control the listener's sense of distance. The signals whose magnitude is controlled by the gain controller 102 are the amplifiers 103a, 1a.
Amplified by 03b and reproduced by the speakers 105a and 105b. By performing the above processing,
It is possible to control the distance of sound.

[0006]

However, even if the reproduced sound is listened at a predetermined position with the above-mentioned structure, since it is controlled only by the direct sound, there is a sense of discomfort from the actual sense of distance.
I couldn't realize the sense of distance in the lateral or backward direction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a sound field reproducing apparatus which can provide a natural sense of distance and a sense of expanse in all directions.

[0008]

According to a first aspect of the present invention, an A / D converter for converting an input audio signal into a digital signal and a digital signal converted by the A / D converter are input. , Signal processing means for performing signal processing so as to obtain an acoustic signal in accordance with the position and distance of the listener and the sound image, input means for inputting the positions of the listener and the sound image, and according to the contents input by the input means Parameter control means for controlling parameters for performing signal processing by the signal processing means so as to obtain characteristics, a D / A converter for converting a signal output from the signal processing means into an analog signal, and D / A converter
It is characterized by comprising an amplifier for amplifying the output of the A converter and a speaker for reproducing the output of the amplifier.

In the invention of claim 2 of the present application, the signal processing means localizes the sound image of the input signal in the direction in which the listener directly hears the sound source and the delay device that delays the input signal according to the reflection time of the reflected sound. Direct sound image localization means for inputting, the signal from the delay device is input, the reflected sound image localization means for localizing the sound image of the reflected sound in the direction of its generation, and the signals from the direct sound image localization means and the reflected sound image localization means. And an adder for performing addition.

In the invention of claim 3 of the present application, the input means inputs the spread of the sound field at the same time, and the signal processing means adds the width of the sound field obtained from the input means to the addition signal obtained from the adder. And a reverberation creating means for adding a reverberation sound corresponding to.

In the invention according to claim 4 of the present application, the signal processing means is provided with frequency characteristic control means for varying the frequency characteristics of the outputs of the direct sound image localization means and the reflected sound image localization means. is there.

[0012]

According to the invention of claim 1 of the present application having such a feature, the position and distance between the listener and the sound image are input by the input means. Then, the audio signal is converted into a digital signal by the A / D converter and input to the signal processing means. Parameters are set in the parameter control means so that characteristics corresponding to the contents input by the input means are obtained, and the acoustic signal corresponding to the input sound field is output from the signal processing means. This signal is converted into an analog signal by the D / A converter and output as an acoustic signal from the speaker via the amplifier.

Further, according to the invention of claim 2, in the signal processing means, direct sound image localization means for locating the input signal at a virtual position corresponding to the position of the direct sound image, and the input signal once depending on the reflection time. A reflected sound image localization means for locating the delayed and reflected signal at the position of the reflected sound is provided, and an acoustic signal is output by adding these outputs. The invention according to claim 3 adds reverberation creating means to generate reverberation in space.
Then, the frequency characteristic is controlled according to the state of the space.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method for localizing sound to the left rear of a viewer using speakers 6-1 and 6-2 placed in front will be described with reference to the principle of sound image localization shown in FIG. In FIG. 3, the signal input means 1 inputs the signal S (t), and its output is input to the digital filters 3-1 and 3-2 via the A / D converters 2-1 and 2-2. It The digital filters 3-1 and 3-2 are blocks that perform signal processing described later, and their outputs are D / A converters 4-1 and 4-.
2, speakers 6-1 and 6 via the amplifiers 5-1 and 5-2
-2 is output.

Now, in FIG. 3, h1 (t) is the response at the position of the speaker 6-1 and the left ear of the listener 7 (more precisely, the response at the position of the eardrum when an impulse is input to the speaker. When performed, it is performed at the position of the ear canal, and so on. The head related transfer function (hereinafter referred to as the impulse response for explanation in the time domain. However, the same result can be obtained even if considered in the frequency domain). , H2 (t) is the impulse response at the position of the speaker 6-1 and the right ear of the listener 7, h3 (t) is the impulse response at the position of the speaker 6-2 and the left ear of the listener 7, h4 (t). ) Is an impulse response at the position of the speaker 6-2 and the right ear of the listener 7. Further, 8 is a signal generating means for generating a signal S (t) such as an impulse signal, 9 is a virtual speaker arranged on the left rear side of the listener, and h5 (t) is the position of the speaker 9 and the left ear of the listener 7. Impulse response at, h
6 (t) is the impulse response at the position of the virtual speaker 9 and the right ear of the listener 7. Further, the digital filters filters 3-1 and 3-2 receive the impulse response hLR from the input signals, respectively.
It is a filter that performs a convolution operation with (t) and hLL (t).

Here, a method for virtually localizing a sound image in an arbitrary direction will be described. The principle of sound field signal reproduction in which a speaker 9 provided on the left side and a substantial sound are virtually generated using the left channel speaker 6-1 and the right channel speaker 6-2 will be described. In the figure, speakers 6-1 and 6-2 are arranged on the left and right front sides of the listener 7. Then, the acoustic signal S (t) corresponding to the rearward or lateral signal S (t) is converted into digital signals 3-1 and 3-2.
Entered in.

In such a configuration, the signal generating means 8
When the signal S (t) from the virtual speaker 9 is output,
The sound that reaches the ear of the listener 7 is as follows. That is, the sound pressure L (t) in the left ear is expressed by the equation (1). L (t) = S (t) * h5 (t) (1) The sound pressure R (t) at the right ear is expressed by the equation (2). R (t) = S (t) * h6 (t) (2) where * represents a convolution operation. In reality, the transfer function of the speaker itself is multiplied, but this may be ignored or the transfer function of the speaker may be included.

Further, the sound pressure, the impulse response and the signal S (t) in the equations (1) and (2) are considered as discrete digital signals on the time axis, and are respectively expressed by the following equations (3) to (7). To convert. L (t) → L (n) ・ ・ ・ (3) R (t) → R (n) ・ ・ ・ (4) h5 (t) → h5 (n) ・ ・ ・ (5) h6 (t) → h6 (n) ・ ・ ・ (6) S (t) → S (n) ・ ・ ・ (7)

In this case, the equations (1) and (2) become the following equations (8) and (9).

[Equation 1]

[Equation 2] Strictly speaking, the natural number n should be expressed as nT, and T
Represents the sampling time, but in general, T is omitted and expressed as in equations (8) and (9). N is the length of the impulse responses h5 (n) and h6 (n).

Similarly, the signal S (t) is sent to the speakers 6-1 and 6-1.
The following expressions (10) and (11) are established for the sound output from 6-2 as a sound and reaching the listener 7. That is, the sound pressure of the left ear is given by the following expression (10). L '(n) = S (n) * hLL (n) * h1 (n) + S (n) * hLR
(n) * h3 (n) (10) The sound pressure of the right ear is given by the following equation (11). R '(n) = S (n) * hLL (n) * h2 (n) + S (n) * hLR
(n) ＊ h4 (n) ・ ・ ・ (11)

If it is assumed that the sounds are generally heard from the same direction if the head-related transfer functions are equal to each other (this assumption is generally correct), the following (12) to (15) are applied.
The formula holds. Therefore, the impulse responses hLL (n) and hLR (n) may be determined so that the expressions (13) and (15) are satisfied.

For example, impulse responses h1 (n) to h6 (n),
When hLL (n) and hLR (n) are rewritten in the frequency domain expression, the following expressions (16) to (23) are obtained. H1 (n) = FFT (h1 (n)) ... (16) H2 (n) = FFT (h2 (n)) ... (17) H3 (n) = FFT (h3 (n))・ (18) H4 (n) = FFT (h4 (n)) ... (19) H5 (n) = FFT (h5 (n)) ... (20) H6 (n) = FFT (h6 (n )) (21) HLL (n) = FFT (hLL (n)) ... (22) HLR (n) = FFT (hLR (n)) ... (23) However, FFT () is It represents a Fourier transformed (FFT) function.

Next, when the expressions (13) and (15) are rewritten in the frequency domain expression, the convolution operation is changed to multiplication as shown in the following expressions (24) and (25), and then the impulse response of each is obtained. Is the Fourier-transformed transfer function.

In the equations (24) and (25), since the values other than the values of the transfer functions HLL (n) and HLR (n) of the FIR filter are obtained by measurement, the following equations (26) and (27) are obtained. Thus, the transfer functions HLL (n) and HLR (n) of the FIR filter can be obtained.

[Equation 3]

[Equation 4] The HLL (n) and HLR (n) thus determined are inverse-Fourier-transformed (IFET) into hLL (n) and hLR (n), and the signal S (n) is converted into digital filters 3-1 and 3-. 2 and the impulse response hLL is applied to the signal input to the speaker 6-1.
(n) is convolved, the impulse response hLR (n) is convolved with the signal input to the speaker 6-2, and the signal is output. In this way, the listener 7 actually hears the speaker 9 on the left rear side.
Even if you don't sound, you can feel that the sound is coming from that direction. With the method described above, the sound image can be virtually localized in any direction.

Next, the sound field reproducing apparatus of the present invention will be described. FIG. 1 is a block diagram showing the overall configuration of a sound field reproducing apparatus according to an embodiment of the present invention. In the figure, the signal processing means 3 is connected to the signal input means 1 via the A / D converter 2. The sound field reproducing device is provided with an input means 10 for inputting the position and distance of the listener and the sound image and the width of the sound field, and the output thereof is given to the parameter control means 11. The parameter control means 11 controls the parameters given to the signal processing means based on conditions such as the position and distance set by the input means 10 and the width of the sound field. The parameter control means stores in advance convolution coefficients for localizing the sound image in all directions and positions as viewed from the listener, and this is selected and set.

FIG. 2 is a block diagram showing a detailed configuration of the signal processing means 3. In the figure, the output from the A / D converter 2 is input to the plurality of delay devices 12-1 to 12-n and the direct sound image localization means 13-0. Delay device 12-1 ~
Reference numeral 12-n is for delaying and attenuating the signal according to the delay time and the delay level set by the parameter control means 11 corresponding to a plurality of reflected sounds in order to give a sense of distance. The outputs of the delay devices 12-1 to 12-n are input to the reflected sound image localization means 13-1 to 13-n. Direct sound image localization means 13-0 and reflected sound image localization means 13-1 to 13-
Both n are digital filters 3-1 and 3-shown in FIG.
2, the convolution coefficient corresponding to the position of the sound image output from the parameter control unit 11 is input as described above. The direct sound image localization means 13-0 is for locating the sound image at the sound image position of the direct sound. or,
The reflected sound image localization means 13-1 to 13-n are respectively the first to nth.
The reflected sound image is localized so as to correspond to the sound image position of the reflected sound. These sound image localization means 13-0 to 13
The left and right outputs of -n are given to the adders 14-1 and 14-2, respectively. The adders 14-1 and 14-2 add and output the left and right acoustic signals, and the D / A shown in FIG.
It is input to the converters 4-1 and 4-2. D / A converter 4-
The configuration after 1, 4-2 is the same as that in FIG.

Next, the operation of this embodiment will be described. First, an audio signal is input to the signal input means 1. The input audio signal is converted into a digital signal by the A / D converter 2, and then enters the signal processing means 3. The direct sound image localization unit 13-0 localizes the signal input to the signal processing unit 3 as a direct sound, and the reflected sound image localization units 13-1 to 13-n localize a sound image for each reflected sound. Input means 10 for inputting the position of the listener and the sound image, the distance, the width of the sound field, and the like, and the input means 10.
The direction and volume of the reflected sound, the reverberation time frequency characteristic, the direct sound image are controlled by the parameter control means 11 which controls the parameters for performing the signal processing by the signal processing means 3 so as to obtain the characteristics according to the input contents. After the size of 7-1-1 is controlled, the signals are output as left and right signals from the signal processing means 3 by the adders 14-1 and 14-2. The signal thus processed is converted into an analog signal by the D / A converter 4-1, then amplified by the amplifiers 5-1 and 5-2, and reproduced from the speakers 6-1 and 6-2. As a result, the listener can localize the sound image by sensing an intended sense of distance and a sense of spaciousness.

Next, the control by the signal processing means 3 will be described. When the listener 7 hears a sound in a certain sound field, FIG.
As shown in (a), the reflection direction of the direct sound D is, for example, 4
If there is a direction, the relationship between the level and time is as shown in FIG. 4 (b), for example. According to the positional relationship between the listener and the sound image, the volume balance between the direct sound D and the initial reflected sound RF1, the time until the initial reflected sound RF1 is generated after the direct sound D is generated, and the reflected sounds from RF1 to RF4 The level balance and time interval will change. As a result, the listener psychologically feels the distance and spread. For example, the reflected sound is
As shown in (b), in the case of four lines, RF1 has a delay time of 5.5 mS and a level of 80% from the direct sound, reflected sound RF2 has a delay time of 7.3 mS and a level of 77%, and RF3 has a delay from the direct sound. The time is 7.9 mS and the level is 76%, the reflected sound RF4 is set by the input means 10 so that the delay time is 17.4 mS and the level is 50%, and the reflected sound image localization means is provided by using the delay devices 12-1 to 12-4, respectively. It outputs to 13-1 to 13-4. The parameter control unit 11 sets a coefficient for realizing the direction of each reflected sound of the reflected sound series stored in advance in the digital filter according to the sound image distance. Then, the positions of the sound images of the direct sound and the respective reflected sounds are realized by the convolution calculation by the digital filter as described above, and the sound images can be localized in a desired direction.

FIG. 5 shows a second embodiment of the invention of claim 3.
It is a block diagram of a sound field reproducing device in an example. This is the reverberation sound creating means 15-1, 15-2 for the output signals from the adders 14-1, 14-2 shown in the configuration of FIG.
Creates and adds reverberation sound according to the size of the sound field.
The reverberation sound creating means is configured, for example, by connecting a plurality of feedback echoes having different delay times in series. When the reverberant sound has a sense of distance up to about 10 m, for example, the reverberant sound has a length of 0.25 to 0.35 seconds and the delay time of the reverberant sound with respect to the direct sound is 50 mS.
To create a sense of distance between 10 m and 20 m, set the reverberation sound length to 0.7 to 0.9 seconds and the reverberation sound delay time from the direct sound to 50 mS, for example. Also, in the case of reproducing a sound field like a wide concert hall, the reverberation time is added so that it is relatively long and the reverberation time in the low range is longer than that in the high range.

FIG. 6 is a block diagram of a sound field reproducing apparatus according to a third embodiment of the present invention. This is shown in Figure 2.
The sound pressure frequency characteristic is controlled by the frequency characteristic control means 16-1 to 16-2n + 2 with respect to each output from the direct sound image localization means 13-0 and the reflected sound image localization means 13-1 to 13-n. To do. For example, when the distance between the listener and the sound image is long, the sound pressure in the high range is set lower than that in the low range. Again 5
When a sense of distance of -10 m is produced, the frequency characteristic is controlled as follows after adding the reflected sound. Frequency 4KHz / gain + 5dB (1 / 3oct-5dB) Frequency 8KHz / gain + 5dB (1 / 3oct-5dB)

FIG. 7 is a fourth embodiment of claim 5 of the present invention.
It is a block diagram of the sound field reproduction apparatus by an Example. In this embodiment, 17 is a parameter receiving means for receiving a control signal for controlling the distance from the outside and the feeling of spread.

The parameter receiving means 17 receives a control signal from the outside including the conditions of the distance and the feeling of spread. The parameter control means 11 controls the parameter set in the signal processing means by the received control signal. The following operation is similar to the operation described in the above embodiment.

As described above, in the present embodiment, the sense of distance and the sense of expanse can be controlled by the control signal from the outside, and the repetitive control is performed by using the preprogrammed signal, and the image and the like are controlled. In combination, it is possible to control the sense of distance and the sense of expanse according to the scene of the image.

Headphones may be used instead of the reproduction speaker, but in that case, correction of crosstalk cancellation is required.

In this embodiment, the case where the input signal is monaural has been described. However, even in the case of stereo, an independent signal processing means is provided for each signal and addition is performed to the adding means 14-1 and 14-2. it can.

[0036]

As described above, according to the present invention, parameters such as sound pressure frequency characteristics and reverberation time frequency characteristics are set according to the position of the listener and the sound image input to the input means, the distance, and the width of the sound field. By controlling, the sound image can be localized at any place other than the reproduction speaker, and sound field reproduction with a sense of distance and a sense of spaciousness can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a sound field reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of signal processing means of the first exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the principle of sound image localization of the present invention.

FIG. 4A is a diagram showing a relationship between reflected sound and direct sound, and FIG. 4B is a graph showing a relationship between level and time.

FIG. 5 is a block diagram of a sound field reproducing device according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a sound field reproducing apparatus according to a third embodiment of the present invention.

FIG. 7 is a block diagram of a sound field reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram of a conventional sound field reproducing apparatus that performs a sense of distance control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 signal input means 2,2-1,2-2 A / D converter 3 signal processing means 3-1,3-2 digital filter 4-1 4-2 D / A converter 5-1 5-2 Amplifiers 6-1, 6-2 Speaker 7 Listener 8 Signal generator 9 Virtual speaker 10 Input means 11 Parameter control means 12-1 to 12-n Delay device 13-0 Direct sound image localization means 13-1 to 13-n Reflected sound image localization means 14-1, 14-2 Adder 15-1, 15-2 Reverberation creation means 16-1 to 16-2n + 2 Frequency characteristic control means 17 Parameter receiving means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H03G 5/24 (72) Inventor Toshihiko Date 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. An A / D converter for converting an input audio signal into a digital signal, and the digital signal converted by the A / D converter is input, and the A / D converter responds to a position and a distance between a listener and a sound image. A signal processing means for performing signal processing so as to obtain an acoustic signal, an input means for inputting a position of a listener and a sound image, and a signal processing means for obtaining a characteristic according to the contents input by the input means. A parameter control means for controlling parameters for processing, a D / A converter for converting a signal output from the signal processing means into an analog signal, and an amplifier for amplifying an output of the D / A converter, A sound field reproducing apparatus comprising: a speaker that reproduces the output of the amplifier. 2. The signal processing means includes a delay device that delays the input signal according to the reflection time of the reflected sound, and a direct sound image localization means that localizes the sound image of the input signal in the sound source generation direction of the direct sound from the listener. A signal from the delay device is input, and a reflected sound image localization means for locating the sound image of the reflected sound in the direction of its generation; and an addition for adding signals from the direct sound image localization means and the reflected sound image localization means The sound field reproducing apparatus according to claim 1, further comprising: 3. The input means inputs the spread of the sound field at the same time, and the signal processing means corresponds to the width of the sound field obtained by the input means in the added signal obtained by the adder. 3. The sound field reproducing apparatus according to claim 2, further comprising reverberation creating means for adding reverberation sound. 4. The sound field according to claim 2, wherein the signal processing means comprises frequency characteristic control means for varying frequency characteristics of outputs of the direct sound image localization means and the reflected sound image localization means. Playback device. 5. The sound field reproducing apparatus according to claim 1, wherein the input unit is a parameter receiving unit that receives a control signal from the outside.