JP2998482B2 - Resonance and reverberation generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonance / reverberation sound generator capable of generating a more natural resonance sound and reverberation sound.

[0002]

2. Description of the Related Art Conventionally, there has been known an apparatus for generating a resonance sound or a reverberation sound using a so-called comb filter (comb filter). The comb filter is a filter provided with a loop circuit having a delay circuit and a filter, and is a filter in which many dips (valleys) like comb teeth appear in frequency characteristics.

FIG. 7 shows an example of a conventional resonance / reverberation sound generator. The device in this figure has four comb filters 7
1, 72, 73, 74, adders 75, 76, 77, and an all-pass filter (APF) 78. The comb filter 71 includes an adder 701, a delay circuit 702, a multiplier 703, and a low-pass filter (LPF) 704.
It has. These units 701 to 704 constitute a loop circuit 705.

[0004] The input tone signal is supplied to each of the comb filters 71 to 7.
Enter 4 The configuration and operation of the comb filters 72, 73, 74 are the same as those of the comb filter 71. However, the delay time of the delay circuit 702, the multiplier of the multiplier 703, the cutoff frequency of the LPF 704, and the like are appropriately changed. Hereinafter, the comb filter 71 will be described, and the description of the other comb filters will be omitted.

The tone signal input to the comb filter 71 is
First, it is input to the adder 701. The output of the adder 701 is
The signal is input to a delay circuit 702 and output to a multiplier 703 after a predetermined delay time. The multiplier 703 includes a loop circuit 70
This is for defining a loop gain of 5 and is multiplied by a predetermined constant. The output of the multiplier 703 is input to the LPF 704. The LPF 704 cuts a high frequency part of the input signal, and inputs the output to the adder 701. Adder 7
01 adds the input tone signal and the output of the LPF 704.

A tap is provided at an appropriate position of the delay circuit 702, from which an output of the comb filter 71 is extracted. The outputs of the comb filters 71 to 74 are added by adders 75 to 77, and the addition result is APF7.
Enter 8 The APF 78 scatters the input signal in the time direction and outputs it as a final resonance / reverberation signal.

FIG. 8 shows an impulse response of one comb filter (for example, comb filter 71). The horizontal axis indicates time, and the vertical axis indicates level. Reference numeral 81 denotes an impulse first input to the comb filter. The input impulse sequentially loops through the loop circuit 705. Since the output is detected when the looped impulse reaches the position of the tap of the delay circuit 702, the impulse response is indicated by reference numeral 8 in FIG.
A pulse train such as 2, 83, 84,...

In particular, as time elapses, the height (level) of the pulse gradually decreases according to the loop gain (multiplier of the multiplier 703). In addition, LPF70
The effect of No. 4 is accumulated, and the pulse shape gradually becomes rounder.

In a standard conventional resonance / reverberation generator, a plurality of such comb filters are connected in parallel as shown in FIG. Alternatively, first, an APF (however, the number of delay stages is several tens to several hundreds stages) is inserted to add pulse scattering due to this. The APF can obtain a scattering effect of an impulse response in a time direction without changing a frequency spectrum as its basic property.

FIG. 9 shows an example of a circuit of the APF. This AP
F includes adders 91 and 93, a delay circuit 92, and multipliers 94 and 95. The input signal is input to the adder 91 and the multiplier 95. The output of the adder 91 is input to the delay circuit 92, and is input to the adder 93 after a predetermined delay time. The multiplier 95 multiplies the input signal by a predetermined multiplier, and inputs the result of the multiplication to the adder 93. The adder 93
The output of the multiplier 95 is subtracted from the output of the delay circuit 92.
The output of the adder 93 becomes the output of the APF and is input to the multiplier 94. The multiplier 94 multiplies the input by a predetermined multiplier, and inputs the multiplication result to the adder 91.

On the other hand, as a technique for controlling the level of a generated resonance sound or reverberation sound, a technique for controlling the level of a resonance sound or reverberation sound in accordance with the level of an input signal is conventionally known.

FIG. 10 shows an example of a conventionally used apparatus for controlling the level of reverberation. The input signal is input to a reverberation circuit 96, which generates and outputs a reverberation sound according to the input signal. The generated reverberation sound is input to a multiplier 97W for level control. Also, the original input signal is
The signal is input to a multiplier 97D for level control. Multiplier 97
The outputs from D and 97W are added by an adder 98. The result of the addition is output as a tone signal to which reverberation has been added.

The multipliers of the level control multipliers 97D and 97W are determined as follows. First, the level of the input signal is detected by the level detection circuit 99. The input signal level is input to the control circuit 100. The control circuit 100
The multipliers of the level control multipliers 97D and 97W are determined and output according to the detected input signal level.

[0014]

However, the above-mentioned FIG.
In the resonance and reverberation sound generator of the above, the effect that the spectrum of the pulse becomes only the low band with time can be obtained,
The degree of pulse scattering is always constant.

However, in actual reverberation in a hall or the like, not only the high-frequency components are lost due to the absorption of the wall as time passes, but also the dispersion in the time direction of the pulse is steadily increased due to various reflections. Naturally, a very natural lingering sound is obtained.

On the other hand, as described above, in the conventional resonance and reverberation sound generating apparatus as shown in FIG. 7, since the degree of pulse scattering is always constant, natural resonance and reverberation in an actual hall or the like occur. There was a problem that a good lingering sound could not be obtained.

Further, since the scattering as shown in FIG. 8 is performed, a signal is output every delay time of the delay circuit 702, and the frequency of the cycle determined by the delay time is emphasized. there were.

Further, since the resonance and reverberation are controlled according to the level of the input signal by the method as shown in FIG. 10, the resonance and reverberation after the level of the input signal becomes zero. Cannot be controlled. Considering the performance in an actual hall or the like, even if the input sound becomes 0, a slight resonance sound or reverberation sound remains, and a natural reverberation can be obtained. In the above method, such a natural reverberation can be obtained. I can't.

A first object of the present invention is to provide a resonance / reverberation sound generating apparatus capable of generating a natural resonance / reverberation sound such as reverberation in an actual hall or the like.

It is a second object of the present invention to provide a resonance / reverberation sound generator capable of controlling resonance / reverberation even when an input signal becomes zero.

[0021]

Means for Solving the Problems] To achieve this object, the present invention is provided with a loop circuit having a delay hand stage
In co-sounding reverberation sound generating device, in said loop circuit
All-bandpass filter means having a delay section disposed
And the delay time of the delay unit of the all-bandpass filter means
Characterized in that a control means for modulating control.

Further, in the resonance sound-reverberation generator using a plurality of loop circuits and a delay means and a low-pass filter means, the cut-off frequency of the low pass filter means in said each loop circuits, in the loop circuit Having a delay time of the delay means of each of the plurality of loop circuits.
Characterized by determined <br/> constant based on the normalized value with a geometric mean of the delay time of the unit.

Further, from a loop circuit having delay means,
Resonance, which is equipped with a generating means for generating a resonance-reverberation
In the reverberation sound generating device, a level detecting means for detecting a level of the resonance sound / reverberation sound, and the loop circuit is circulated.
That a multiplier for multiplying the predetermined multiplier loop signal, based on the level of the record <br/> level detection means detects the resonant sound-reverberation control multiplier said multiplier multiplies the loop signal And control means for performing the control.

[0024]

[0025]

If the all-pass filter means for scattering the input signal in the time axis direction is provided in the loop circuit of the comb filter, the signal circulating in the loop circuit is scattered in the time axis direction, and more natural. Resonance and reverberation are obtained.

Further, if the cut-off frequency of the low-pass filter is determined based on the delay time of the delay means in the comb filter, it is possible to simulate the attenuation of high frequency components for sound that has propagated long in the air.

Further, if the level of the resonance sound / reverberation sound is controlled based on the output level of the generated resonance sound / reverberation sound, the level of the resonance sound / reverberation sound can be controlled even after the input signal becomes zero. In particular, desired level control can be performed at a minute level. In particular,
The reverberation level may be controlled by controlling the level of a loop signal circulating through a loop circuit of the comb filter.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a resonance / reverberation sound generator according to a first embodiment of the present invention. The device in this figure has four comb filters 11, 12, 13, 14,
It has adders 15, 16, 17 and an APF 18. The comb filter 11 includes an adder 101, a delay circuit 10
2, APF 103, multiplier 104, and LPF 105
It has. These units 101 to 105 constitute a loop circuit 106. The feature is that the APF 103 is provided in the loop circuit as compared with the comb filter 71 of FIG.

The input tone signal is supplied to each of the comb filters 11-1.
Enter 4 The configuration and operation of the comb filters 12, 13, and 14 are the same as those of the comb filter 11. However, the delay time of the delay circuit 702, the parameter of the APF 103,
The multiplier of the multiplier 704 and the cutoff frequency of the LPF 705 are appropriately changed. Hereinafter, the comb filter 11 will be described, and the description of the other comb filters will be omitted.

The adder 101, the delay circuit 102, the multiplier 104 and the LPF 105 constituting the loop circuit of the comb filter 11 are composed of the adder 70 of the comb filter 71 shown in FIG.
1, delay circuit 702, multiplier 703, and LPF 70
The operation is the same as that of No. 4. In the comb filter 11, since the APF 103 is provided in the loop circuit 106, a signal circulating in the loop circuit is scattered in the time direction.

FIG. 2 shows an impulse response of the comb filter 11. The horizontal axis indicates time, and the vertical axis indicates level. Reference numeral 21 denotes an impulse first input to the comb filter 11. The input impulse sequentially loops through the loop circuit 106. When the looped impulse reaches the tap position of the delay circuit 102, an output is detected. LPF10
5 and the operation of the multiplier 104, as described with reference to FIGS.
And the pulse shape becomes rounder.

The APF 10 in the loop circuit 106
No. 3 scatters the pulse in the time direction every time the signal makes one round. Therefore, as the time elapses, the pulse is scattered, and the shape becomes indistinct.

Here, as the APF 103, the one described with reference to FIG. 9 may be used. The number of stages of the internal delay circuit is
It is preferable to set the number of stages of the delay circuit 102 in the loop to several percent to several tens percent.

Referring again to FIG. 1, each comb filter 11
To 14 are added by adders 15 to 17,
The result of the addition is input to the APF 18. APF18 is
The input signal is scattered in the time direction and output as a final resonance / reverberation signal.

In the prior art described with reference to FIG. 7, the tone generated in the hall is reflected on the wall of one hall, and the reflection is reflected on the other wall.
Only one reflection path could be simulated. On the other hand, according to the above embodiment, when the musical sound generated in the hall is reflected on the wall of one hall and the reflection is reflected on the other wall, it is dispersed in all directions and slightly shifted. The reflection path can also be simulated. this is,
When a resonance sound or a reverberation sound is generated by simulating a hall having a complicated wall or the like, it follows an actual natural phenomenon, and a more natural resonance sound or a reverberation sound can be obtained. In addition, the configuration is simple because the APF only needs to be provided in the loop circuit.

Further, since the signal circulating in the loop circuit 106 is temporally dispersed by the APF 103, the frequency having the cycle of the delay time of the delay circuit in the loop circuit as described with reference to FIGS. There is no such thing.

Next, a modified example of the first embodiment will be described.

In FIG. 1, the APF 103 has been described as having the configuration shown in FIG. 9, but may be an APF having the configuration shown in FIG. The APF of FIG. 3 is similar to that of FIG.
9 correspond to the reference numerals 91 to 95 in FIG.

However, in the APF shown in FIG.
Is modulated in accordance with the output of the LFO 36.
The LFO 36 outputs a low-frequency signal such as a waveform 37, for example. The waveform is not limited to this waveform, and another waveform may be used, or the delay time may be modulated by noise.

As described above, by modulating the delay time of the delay circuit 32, the interval of dispersion by the APF 103 in FIG. 1 is changed, and more natural resonance and reverberation can be obtained.

When the APF shown in FIG. 3 is used, each comb filter may use LFOs having different phases and different frequencies, or LFOs having the same frequency with different phases. Also, the delay circuit 1 in the loop circuit of FIG.
The frequency of the LFO 36 may be scaled according to the delay time length 02, and the frequency of the LFO 36 may be lowered when the delay time is long. In this manner, the degree of dispersion may be varied each time the signal is delayed by circulating through the loop circuit of the comb filter.

Next, a second embodiment of the present invention will be described. The apparatus of this embodiment has the same configuration as that of FIG. However, the cutoff frequency of the LPF 105 in the comb filters 11 to 14 is scaled according to the delay time of the delay circuit 102.

The delay circuit 102 in the comb filter is
This means sound propagating in the air, but sound propagating in the air is actually attenuated by friction with the air. In particular, sounds with higher frequencies are more attenuated. Therefore, in order to simulate this phenomenon, in the conventional apparatus, the LPF 105 is provided in the comb filter. And LPF1
The cutoff frequency of 05 was set as a result of trial and error.

Strictly speaking, the longer the delay time of the delay circuit 102 in the comb filter (corresponding to the longer the sound propagates in the air), the greater the attenuation of high frequency components. Therefore, in this embodiment, the cutoff frequency of the LPF 105 is changed according to the delay time of the delay circuit 102 in the comb filter.

Specifically, the cutoff frequency is determined as follows.

First, assuming that there are N comb filters, the number of delay circuits therein is also N. The average (the geometric mean) La of the delay time lengths of the N delay circuits is calculated by the following equation (1). Ln (n = 1, 2,... N)
Indicates the delay time length of each delay circuit.

[0048]

(Equation 1)

The cutoff frequency fn of the LPF 105 in each comb filter is obtained by the following equation (2). fc and Sfc are predetermined constants. fc is Ln / La = 1
It corresponds to the value of the cutoff frequency at the time of.

[0050]

(Equation 2)

Various scalings can be realized by changing the constant Sfc. First, when Sfc = 0, fn
= Fc, and no scaling is performed. When Sfc <0, fn decreases as Ln / La increases, which follows the physical phenomenon described above. Normally Sfc
<0, for example, Sfc = −1. When Sfc> 0, fn increases as Ln / La increases, and scaling opposite to the above-described physical phenomenon is performed.

Further, similarly, the multiplier Gn (n = 1, 2,... N) of the multiplier 104 in the comb filter may be set to a value calculated by the following equation (3). G0 is a predetermined constant.

[0053]

(Equation 3)

As a result, when the delay time length of the delay circuit 102 is long, the signal is attenuated quickly.

Next, a third embodiment of the present invention will be described. This is an apparatus that can control a resonance sound and a reverberation sound even when an input signal becomes zero.

FIG. 4 shows a block configuration of the device according to the third embodiment. This device includes a delay circuit 401, comb filters 402-1 to 402-N, adders 403L and 403R,
APF 404L, 404R, multipliers 405L, 405
R, adders 406L and 406R, multipliers 407L and 40
7R, an adder 408, a level detector 409, and a controller 410.

The comb filter 402-1 includes a multiplier 42
1, adder 422, delay circuit 423, APF 425, multiplier 426, LPF 427, and multipliers 424L, 4
24R. Comb filters 402-2 to 402
The configuration and operation of −N are the same as those of the comb filter 402-1, and thus description thereof is omitted.

FIG. 5 shows the details of the level detection section 409 and the control section 410. The level detection unit 409 includes a full-wave rectifier 501 and an LPF 502. Control unit 41
0 is a coefficient table 50 on a separately provided memory.
3 is referred to.

The operation of this embodiment will be described with reference to FIGS. In FIG. 4, the comb filters 402-1 to 402-1
402-N, adders 403L and 403R, and APF
Reference numerals 404L and 404R denote circuits for generating reverberation in response to input signals, and are the same as those shown in FIG.

However, in the comb filter 402-1 of FIG. 4, the level of the input signal is adjusted by the multiplier 421. Further, from the delay circuit 423, the left output and the right output are extracted from the two taps, and the multiplier 424L,
The level is adjusted at 424R and output.
fd1 indicates a multiplier of the multiplier 426 for adjusting the gain of the loop circuit.

The input signal is input to the comb filters 402-1 to 402-N via the delay circuit 401 for forming the initial reflected sound. Then, in the same manner as described with reference to FIG.
Up to the PFs 404L and 404R, left and right reverberations are generated. These reverberation signals are supplied to a multiplier 405L,
405R, and the level is adjusted.
L, 406R.

The original input signal is supplied to the multiplier 407L,
407R, the level is adjusted,
L, 406R. Adders 406L, 406R
Are the outputs of multipliers 405L and 405R and multiplier 40
The outputs of 7L and 407R are added and output as a tone signal to which reverberation has been added.

In this embodiment, the level of the reverberation is controlled by the multiplier fd1 of the multiplier 426 in the comb filter 402-1 (the multipliers fd2, fd3, f in other comb filters).
d4,...). First, APF
The reverberant sound outputs from 404L and 404R are extracted and added by an adder 408. The addition result is output to the level detector 409.
To enter.

Referring to FIG. 5, the input to level detector 409 (representing the reverberation level) is full-wave rectified by full-wave rectifier 501 and averaged by LPF 502. LPF50
The output of 2 is a signal indicating an average reverberation level.

The control section 410 periodically scans the output of the LPF 502, and compares the obtained reverberation sound level with predetermined threshold values SH1, SH2, and SH3.
When the reverberation level is equal to or less than the threshold value SH1 and greater than SH2, the multiplier data 51 of the coefficient table 503 is used.
1 is read out and output as multipliers fd1, fd2, fd3,. Similarly, the reverberation level is set to the threshold value SH.
If it is less than 2 and greater than SH3, the multiplier data 512
Multiplier data 513 when threshold value SH3 or less
Are read, and multipliers fd1, fd2, fd3,
Output as ...

FIG. 6 is a graph showing the reverberation level which changes with time. In the conventional method, the reverberation sound level is controlled in accordance with the input signal. Therefore, when the input level becomes 0, the signal has to be attenuated by a specified curve thereafter. A dotted line 61 in FIG. 6 indicates a change in reverberation sound level according to the conventional method.

On the other hand, according to this embodiment, when the reverberation level is equal to or lower than the threshold value SH1 and higher than SH2, the multiplier fd corresponding to the reverberation level of such a level.
The level of the reverberant sound is controlled by 1, fd2,..., And as the level further decreases, the reverberant sound level is controlled by a multiplier corresponding to the level. Therefore, as shown by the solid line 62 in FIG.
Control at a minute level is possible.

Each of the comb filters 402-1 to 402-1
−F the respective coefficients fd1, fd of the multiplier 426 in N
Since the reverberation sound level is controlled by changing 2,..., Proper control can be performed even when the level is minute.

In this embodiment, the level is detected by adding the left reverberation sound and the right reverberation sound. However, the level may be detected from only the right reverberation sound or the left reverberation sound. Further, the reverberation sound level at the last stage is detected, but the reverberation level may not be the last stage.

[0070]

As described above, according to the present invention, a filter for scattering an input signal such as an all-pass filter in the time axis direction is provided in a loop circuit of a comb filter (comb filter). As the time elapses, the reverberation sound is scattered, and a natural resonance sound or reverberation sound like a reverberation in an actual hall or the like can be generated.

Also, since the cutoff frequency of the low-pass filter means in the comb filter is determined based on the delay time of the delay means, it is possible to simulate the attenuation of high frequency components in sound that has long propagated in the air. Therefore, more natural resonance and reverberation can be generated.

Further, since the reverberation sound level is controlled by controlling the loop gain in the comb filter according to the level of the generated reverberation sound, the resonance and reverberation can be maintained even after the input signal becomes zero. The level of the sound can be controlled, and the desired level control can be performed particularly at a minute level.

[Brief description of the drawings]

FIG. 1 is a block diagram of a resonance / reverberation sound generator according to a first embodiment of the present invention;

FIG. 2 is a graph showing an impulse response of a comb filter.

FIG. 3 is a block diagram of an APF used in a modification of the first embodiment;

FIG. 4 is a block diagram of a resonance / reverberation sound generator according to a third embodiment.

FIG. 5 is a block diagram showing details of a level detection unit and a control unit;

FIG. 6 is a graph showing a reverberation level that changes with time.

FIG. 7 is a block diagram of a conventional resonance / reverberation sound generator.

FIG. 8 is a graph showing an impulse response of a comb filter.

FIG. 9 is a block diagram of an APF.

FIG. 10 is a block diagram of a conventional apparatus for performing reverberation level control.

[Explanation of symbols]

11, 12, 13, 14 ... comb filters, 15, 16,
17: adder, 18: all-pass filter (APF),
101: adder, 102: delay circuit, 103: APF,
104: multiplier, 105: LPF.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-83798 (JP, A) JP-A-5-19771 (JP, A) Full-scale operation 64-32598 (JP, U) Real-time operation 120496 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G10K 15/12 G10H 1/00

Claims (3)

(57) [Claims] 1. A co-sounding reverberation sound generating apparatus equipped with a loop circuit having a delay hand stage, the all-pass filter means having a delay unit which is disposed in the loop circuit, the all-pass The delay time of the delay section of the
Resonant sound reverberation sound generating apparatus characterized by comprising a control means for controlling tone. In resonant sound-reverberation generator using a plurality of loop circuits having 2. A delay means and the low-pass filter means, the cut-off frequency of the low pass filter means in said each loop circuits, in the loop circuit delay time of the delay means of
Delay time of delay means of each of the plurality of loop circuits
Geometric mean at the resonance tone, reverberation sound generating device, characterized in that the decision on the basis of the normalized value of. 3. A resonance / reverberation sound generating apparatus which comprises a generation means comprising a loop circuit having a delay means and generates a resonance / reverberation sound, wherein a level detection means for detecting a level of the resonance / reverberation sound ; Multiply a loop signal circulating in the loop circuit by a predetermined multiplier
A multiplier calculated for, based on the level of said level detecting means detects resonant sound-reverberation, multiply the multiplier multiplies the loop signal
A resonance / reverberation sound generator, comprising: control means for controlling the number .