JPH0944176A - Method for generating reverberation sound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary an auditory feeling of the size of a room for an arbitrary sound source signal. SOLUTION: When a pulse train showing features of a reproduction sound field 4 is already known like the time waveform 13 of the original pulse train, the pulse train is added to the input from an arbitrary signal source 7 by the delay unit 91 and amplifier 92 of an FIR filter 9. Further, after a timbre controller 10 controls the timbre, an amplifier 11 amplifies the signal and inputs it to a speaker 5 in the reproduction sound field 4. A listener 6 can listen to the sound to which a reverberation sound is added. At this time, a controller 8 varies a delay value set for the delay unit 91 to obtain the time waveform 14 of the pulse train after 'size feeling of room' variation. Consequently, the auditory feeling of the size of the room that the listener 6 has can be varied.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an arbitrary sound source signal,
The present invention relates to a method of generating a reverberant sound by constructing an FIR filter with a delay device and an amplifier using a delay value and an amplitude value of a pulse train representing the characteristics of a sound field.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of an apparatus for implementing a conventional reverberation sound generation method. In FIG. 4, 1
Is a signal source and is connected to the FIR filter 2.
Reference numeral 3 is an amplifier, and the output side of the amplifier is connected to the speaker 5 of the reproduced sound field 4. 6 is a listener.

Next, the operation of the above conventional example will be described.
The signal from the signal source 1 is convoluted by the FIR filter 2 generated based on the impulse response measured in the sound field, the FIR filter output is amplified by the amplifier 3, and the amplified output is sent to the speaker 5. Supply. In the reproduction sound field 4, the listener 6 listens to the sound waves emitted from the speaker 5. In this way, even in the conventional method, the reverberation sound can be added using the impulse response measured in the sound field.

[0004]

However, in the above-described conventional reverberation sound generation method, the auditory sense of room size is determined by the sound field in which the impulse response is measured, and the sense of room size cannot be changed. There was a problem.

It is an object of the present invention to solve the conventional problems described above and to provide a reverberant sound generation method capable of changing the perceptual room size.

[0006]

In order to achieve the above-mentioned object, the first method of the present invention is to use a delayer for an arbitrary sound source signal by using a delay value and an amplitude value of a pulse train representing a characteristic of a sound field. In a method of generating a reverberant sound by configuring an FIR filter with an amplifier and an amplifier, the perceptual sense of room size is changed by changing the delay value given to the delay device. The second method is to change only the sense of room size while keeping the audible reverberation constant by changing the amplitude value given to the amplifier so that the reverberation time becomes a desired value. Characterize.

A third method is that the FIR filter is composed of a plurality of channels, and different delay values and amplification values are set between the FIR filters, so that the total calculation amount remains constant and the auditory perception is maintained. It is characterized by creating a feeling of spatial expanse while maintaining naturalness.

[0008]

Therefore, according to the present invention, in the first method, the time axis of the pulse train can be expanded or contracted by changing the delay value given to the delay device of the FIR filter by the controller. As a result, it is possible to control the auditory sense of room size.

In the second method, the auditory sense of room size is changed, and at the same time, the amplitude value given to the amplifier of the FIR filter is changed so that the reverberation time becomes a desired value. It is possible to change only the size of the room while maintaining a constant reverberation.

Furthermore, in the third method, the auditory sense of room size is changed, and at the same time, the FIR filter is composed of a plurality of channels and different delay values and amplification values are recognized between the FIR filters. Thereby, it is possible to generate a spatial expansive feeling while keeping the audible naturalness while keeping the total amount of calculation constant.

[0011]

Embodiments of the present invention will be described below.
FIG. 1 is a block diagram showing a configuration example of an apparatus for carrying out the first method of the present invention. In FIG. 1, 7 is an arbitrary signal source, and 8 is a controller for controlling the delay device 91 of the FIR filter 9, which sets a delay value ti of (Equation 1) described later. The FIR filter 9 consists of a delay unit 91 and amplitude value g ₁ to g _n of the amplifier 92 of the delay time t ₁ ~t _n. Reference numeral 10 is a tone color controller including n tone color control filters Filter 1 to n, and 11 is an amplifier. The other speakers 5 and listeners 6 in the reproduced sound field 4 are the same as those in FIG.

As shown in FIG. 1, an arbitrary signal source 7 is connected to an FIR filter 9 including a delay device 91 and an amplifier 92. Further, the controller 8 can control the delay value given to the delay device 91. The output of the amplifier 92 is a tone color controller
It is input to the amplifier 11 via 10 and the speaker 5 of the reproduced sound field 4
Input. The listener 6 listens to the acoustic signal emitted from the speaker 5.

Next, the operation of the first method according to this configuration example will be described. The output of the arbitrary signal source 7 is input to the FIR filter 9 including the delay device 91 and the amplifier 92. The pulse train delay value toi (i = 1, 2, ..., N) and amplitude value goi (i =
1, 2, ..., N), the controller 8 sets the delay value ti in the delay device 91 as shown in (Equation 1).

[0014]

## EQU1 ## ti (i = 1, 2, ..., N) = α × toi (i =
1, 2, ..., N) where α is a coefficient and the amplitude value gi is set in the amplifier 92 as shown in (Equation 2).

[0015]

## EQU00002 ## gi (i = 1, 2, ..., N) = goi (i = 1,
2, ..., N) The pulse train representing the characteristics of the sound field may be calculated by a known inverse filter process using the impulse response measured in the sound field, or the pulses are selected in descending order of amplitude. The method may be used, or the method of detecting the maximum value of the amplitude while performing the masking process may be used. Alternatively, the pulse train representing the characteristics of the sound field may be calculated by a simulation using a sound ray method or a mirror image method. With either method, the number of pulses is 100m
200 or more per s is required, and if 400 or more per 100 ms, audibly natural reverberation can be generated.

Next, by changing the coefficient α in the controller 8, the perceptual room size can be controlled as shown by the time waveform 14 of the pulse train after the "room size" is changed. When α = 1, the same sense of room size as the original pulse train can be obtained. When α> 1, the feeling of room size becomes large, and when α <1, the feeling of room size becomes small. When the range of coefficient α is set to 0.1 <α <2.0, a reverberant sound that is natural to the listener can be obtained.

Next, the output of the delay device 91 is input to the amplifier 92. Amplitude value gi of this amplifier 92 (i = 1, 2, ..., N)
Is constant, so that if the coefficient α of the controller 8 is reduced to reduce the feeling of room size, the reverberation also decreases accordingly.

Further, the output of the amplifier 92 is input to the tone color controller 10. The tone color controller 10 is necessary to generate a reverberant sound that is natural to the sense of hearing, and preferably has a frequency characteristic calculated from the reverberation time frequency characteristic. However, in practice, a low-pass filter that becomes steeper in the later time period may be used. At this time, the circuit can be realized by the FIR filter 9, but in order to reduce the amount of calculation, it is preferable that the circuit is formed by an IIR filter, and it can be realized by an IIR filter of about 1 to 2 stages. In the example of this device, one tone color control filter (Fil filter) is provided for each delay device 91 and each amplifier 92.
ter1 to n) are provided, one timbre control filter may be provided for a plurality of delay devices 91 and amplifiers 92,
Providing one or more timbre control filters per 100 ms duration produces a reverberant sound that is natural to the listener.

The output of the tone color controller 10 is combined and input to the amplifier 11 and the speaker 5 in the reproduced sound field 4. The signal input to the speaker 5 becomes an acoustic signal and reaches the listener 6.

The apparatus according to the first method of the present invention configures an FIR filter with a delay device and an amplifier by using the delay value and the amplitude value of a pulse train representing the characteristics of a sound field, and changes the delay value given to the delay device. By doing so, it is possible to change the auditory sense of room size.

FIG. 2 is a block diagram showing a structural example of an apparatus for carrying out the second method of the present invention. In FIG. 2, reference numeral 12 is a controller for controlling the amplifier 92 of the filter 9 and sets an amplitude value gi of (Equation 3) described later. Other than the above, the blocks having the same functions as those in FIG.

Next, the operation of the second method according to this configuration example will be described. The output of the arbitrary signal source 7 is input to the FIR filter 9 including the delay device 91 and the amplifier 92. Delay value toi (i = 1, 2, ..., N) of the pulse train that represents the characteristics of the sound field
And the amplitude value goi (i = 1, 2, ..., N),
The delay value ti is set to 91 as described above (Equation 1). Further, the amplitude value gi is set in the amplifier 92 as shown in (Equation 3).

[0023]

## EQU3 ## gi (i = 1, 2, ..., N) = β × goi (i =
1, 2, ..., N) However, the coefficient β can be expressed as in (Equation 4) using the reverberation time RTo of the original pulse train.

[0024]

## EQU00004 ## .beta. = 10.0 ^ {60.0.times. (1-.alpha.) / RTo / 20.0} The calculation method of the pulse train representing the characteristics of the sound field is based on the impulse response measured in the sound field, and the known inverse filter processing The method may be used, pulses may be selected in descending order of amplitude, or the maximum amplitude may be detected while masking. Alternatively, the pulse train representing the characteristics of the sound field may be calculated by a simulation using a sound ray method or a mirror image method. With either method, the number of pulses is 100m
200 or more per s is required, and if 400 or more per 100 ms, audibly natural reverberation can be generated.

By changing the coefficient α in the controller 8, it is possible to control the auditory sense of room size. α = 1
At that time, the same sense of room size as the original pulse train can be obtained.

When α> 1, the feeling of room size becomes large, and when α <1, the feeling of room size becomes small. Coefficient α
If the range is set to 0.1 <α <2.0, a reverberant sound that is natural to the listener can be obtained.

The output of the delay device 91 is input to the amplifier 92.
This amplifier 92 has an amplitude value gi (i
= 1, 2, ..., N) is changed according to (Equation 3), so the reverberation is constant even if the size of the room is changed by controlling the coefficient β of the controller 12.

Further, the output of the amplifier 92 is input to the tone color controller 10. The tone color controller 10 is necessary to generate a reverberant sound that is natural to the sense of hearing, and preferably has a frequency characteristic calculated from the reverberation time frequency characteristic. However, in practice, a low-pass filter that becomes steeper in the later time period may be used. At this time, the circuit can be realized by an FIR filter, but it is preferable to configure the circuit by an IIR filter in order to reduce the amount of calculation, and it can be realized by an IIR filter having about one or two stages. In this example of the device, one tone color control filter (Fil filter) is provided for each delay device 91 and each amplifier 93.
ter1 to n) are provided, one timbre control filter may be provided for a plurality of delay devices 91 and amplifiers 92,
Providing one or more timbre control filters per 100 ms duration produces a reverberant sound that is natural to the listener.

Then, the output of the tone color controller 10 is combined and input to the amplifier 11 and then to the speaker 5 in the reproduced sound field 4. The signal input to the speaker 5 becomes an acoustic signal and reaches the listener 6.

In the apparatus according to the second method of the present invention, an FIR filter is constructed by a delay device and an amplifier using the delay value and the amplitude value of the pulse train representing the characteristics of the sound field, and the delay value given to the delay device is changed. By changing the auditory sense of room size, the amplitude value given to the amplifier is changed so that the reverberation time becomes a desired value, so that the auditory reverberation feeling is kept constant. Only the feeling of size can be changed.

FIG. 3 is a block diagram showing a structural example of an apparatus for carrying out the third method of the present invention. In FIG. 3, the configuration different from that of FIGS. 1 and 2 is that the output of the audio controller 10 is input to either of the two amplifiers 11a or 11b and output to the two speakers 5a and 5b in the reproduced sound field 4, respectively. It has become so.

Next, the operation of the third method according to this configuration example will be described. The output of the arbitrary signal source 7 is input to the FIR filter 9 including the delay device 91 and the amplifier 92. Pulse train delay value toi (i = 1, 2, ...,
n) and the amplitude value goi (i = 1, 2, ..., N), the delay value ti is set in the delay device 91 as in the above (Equation 1). Further, the amplitude value gi is set in the amplifier 92 as in the above (Equation 3).

The method of calculating the pulse train representing the characteristics of the sound field is as follows:
Using the impulse response measured in the sound field, it may be a method by known inverse filter processing, a method of selecting pulses in descending order of amplitude, or a method of detecting the maximum value of amplitude while performing mask processing. Good. Alternatively, the pulse train representing the characteristics of the sound field may be calculated by a simulation using a sound ray method or a mirror image method. In either method, the number of pulses needs to be 200 or more per 100 ms, and if 400 or more per 100 ms, a reverberant sound that is audibly natural can be generated.

By changing the coefficient α in the controller 8, the auditory sense of room size can be controlled. α = 1
At that time, the same sense of room size as the original pulse train can be obtained.

When α> 1, the feeling of room size is large, and when α <1, the feeling of room size is small. Coefficient α
If the range is set to 0.1 <α <2.0, a reverberant sound that is natural to the listener can be obtained.

The output of the delay device 91 is input to the amplifier 92.
This amplifier 92 has an amplitude value gi (i
= 1, 2, ..., N) is changed according to (Equation 3), so the reverberation is constant even if the size α of the room is changed by controlling the coefficient α of the controller 8. In this example of the apparatus, the coefficient β of the controller 12 is provided so that the reverberation is constant. However, when the reverberation is not particularly required to be constant, the controller 8 is used as in the first method. May be only.

Further, the output of the amplifier 92 is input to the tone color controller 10. The tone color controller 10 is necessary to generate a reverberant sound that is natural to the sense of hearing, and preferably has a frequency characteristic calculated from the reverberation time frequency characteristic. However, in practice, a low-pass filter that becomes steeper in the later time period may be used. At this time, the circuit can be realized by an FIR filter, but it is preferable to configure the circuit by an IIR filter in order to reduce the amount of calculation, and it can be realized by an IIR filter having about one or two stages. In the example of this device, one tone color control filter (Fil filter) is provided for each delay device 91 and each amplifier 92.
ter1 to n) are provided, one timbre control filter may be provided for a plurality of delay devices 91 and amplifiers 92,
Providing one or more timbre control filters per 100 ms duration produces a reverberant sound that is natural to the listener.

The output of the tone color controller 10 has two amplifiers.
Input either 11a or 11b. In this configuration example, among Filter i (i = 1, 2, ..., N) in the tone color controller 10,
Amplifiers 11a and 1 to be input depending on whether Filter i is odd or even
Although 1b is determined, the number of outputs of the tone color controller assigned to the amplifiers may be set to be substantially the same, so that the amplifiers to be input may be determined according to a random number table, for example. The outputs of the two amplifiers 11a and 11b are input to the two speakers 5a and 5b in the reproduced sound field 4, respectively.
The signals input to the speakers 5a and 5b become acoustic signals and reach the listener 6. In this way, the FIR filter is configured with two channels, and the delay value and the amplification value that are different between the FIR filters are set, so that the total calculation amount remains constant and the auditory naturalness is maintained. It is possible to create a feeling of expansiveness. In this configuration example, two channels are used, but two or more channels may be used as long as the listener can hear the output of each speaker.

In the apparatus according to the third method of the present invention, an FIR filter is constructed by a delay device and an amplifier by using the delay value and the amplitude value of the pulse train representing the characteristics of the sound field, and the delay value given to the delay device is changed. By changing the auditory sense of room size, the FIR filter is composed of a plurality of channels, and different delay values and amplification values are set between the FIR filters, so that the total calculation amount is increased. Can be kept constant, and a spatial expansive feeling can be generated while maintaining the audible naturalness.

[0040]

As described above, according to the first method of the present invention, the time axis of the pulse train can be expanded or contracted by changing the delay value given to the delay device of the FIR filter by the controller. As a result, the size of the room that is audible can be controlled.

In addition, in the second method, the auditory sense of room size is changed, and at the same time, the amplitude value given to the amplifier of the FIR filter is changed so that the reverberation time becomes a desired value. It is possible to change only the size of the room while maintaining a constant reverberation.

Further, in the third method, while changing the auditory sense of room size, the FIR filter is constituted by a plurality of channels and different delay values and amplification values are recognized among the FIR filters. Thereby, it is possible to generate a spatial expansive feeling while keeping the audible naturalness while keeping the total amount of calculation constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an apparatus for carrying out a first method of the present invention.

FIG. 2 is a block diagram showing a configuration example of an apparatus for carrying out a second method of the present invention.

FIG. 3 is a block diagram showing a configuration example of an apparatus that carries out a third method of the present invention.

FIG. 4 is a block diagram showing a configuration of an apparatus that implements a conventional reverberation sound generation method.

[Explanation of symbols]

4 ... Playing sound field, 5, 5a, 5b ... Speaker, 6 ... Listener, 7 ... Signal source, 8 ... Controller (α), 9 ... FIR filter, 10 ... Tone controller, 11, 11a, 11b ... Amplifier ,
12 ... Controller (β), 13 ... Original pulse train time waveform,
14… Time waveform of the pulse train after changing the “sense of room size”
91 ... delay device, 92 ... amplifier.

Claims (3)

[Claims] 1. A method for generating a reverberation sound by constructing a FIR filter with a delay device and an amplifier using a delay value and an amplitude value of a pulse train representing characteristics of a sound field for an arbitrary sound source signal, the delay device comprising: A method for generating reverberant sound, characterized in that the perceptual room size is changed by changing the delay value given to the. 2. The method according to claim 1, wherein the amplitude value given to the amplifier is changed so that the reverberation time becomes a desired value, and only the sense of room size is changed while keeping the audible reverberation constant. The method for generating reverberant sound according to claim 1. 3. The FIR filter is composed of a plurality of channels, and different delay values and amplification values are set among the FIR filters so that the total calculation amount remains constant.
2. The reverberant sound generation method according to claim 1, wherein a spatial expansive feeling is generated while maintaining audible naturalness.