JPH04149599A - Reverberation sound generation device - Google Patents

Abstract

PURPOSE:To disperse a reverberation sound equally without any deviation with time by making the number of samples, which correspond to respectively delay times of plural comb line filters, prime with one another. CONSTITUTION:A digital audio signal which is supplied to an input terminal IN is supplied to the respective comb line filters 11 - 1n. Each sample value of the input digital audio signal is delayed by each of delay times T1 - Tn through the comb line filters 11 - 1n and then the signal level decreases gradually each time each delay time is elapsed. The output signals of the filters 11 - 1n are added by an adder 2, whose output is further delayed by APFs 31 - 3n. The delay times T1 - Tn of the delay elements of the filters 11 - 1n are different from one another and given as multiples of a sampling period. The numbers of samples corresponding to the delay times, i.e. delay sample numbers are made mutually prime.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a reverberation sound generation device using a plurality of comb filters.

BACKGROUND ART Reverberation sound generation devices are known for adding reverberation effects to audio signal sounds. As a conventional reverberation sound generation device, there is a device that generates reverberation sound by connecting a plurality of comb filters having different delay time characteristics in parallel and synthesizing the output signals of the comb filters. however,
In such a conventional device, there is a problem in that the sound quality of reverberant sound deteriorates when the innoculus responses overlap between the <C-shaped filters.

OBJECTS OF THE INVENTION An object of the present invention is to provide a reverberant sound generation device that can improve the sound quality of reverberant sound by preventing innocuous responses from overlapping between comb filters.

Structure of the Invention The reverberation sound generation device of the present invention includes a delay element that delays an input digital audio signal for each sample data, and a multiplication unit that multiplies the delayed signal output from the delay element by a coefficient and returns the result to the input of the delay element. A device comprising: a plurality of comb filters having means for outputting delayed signals; and an addition means for adding output signals of the plurality of comb filters;
It is characterized in that the number of samples corresponding to each delay time of the plurality of comb filters is relatively prime.

Effects of the Invention In the reverberant sound generation device according to the present invention, the number of samples corresponding to each delay time of a plurality of comb filters is made prime to each other, so that the impulse responses of each comb filter almost match within the reverberation time. You can try to avoid it. As a result, the reverberant sound is dispersed evenly and temporally, making it possible to obtain good reverberant sound quality.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the reverberant sound generating device according to the present invention shown in FIG. 1, the input terminal IN has a plurality of comb filters]
. (n is the number of comb filters) are connected. An adder 2 is connected to the output end of the comb filter 11 or 1°. A plurality of APFs (all-pass filters) 3; to 3m (m is the number of APFs) are connected in cascade to the output end of the adder 2. The output end of APF3m is connected to the output terminal OUT of this device. In addition, APF3
The filters 1 to 3m are, for example, second-order IIR type filters, and have a constant gain with respect to frequency and different group delay characteristics. Regarding this APF, for example, JP-A-62-
It is disclosed in Japanese Patent No. 161210, and will not be described in detail here.

The comb filters II to 1n each include an adder 6, a delay element 7, and a multiplier 8, as shown in FIG.

That is, the input signal is supplied to the delay element 7 via the adder 6, and is delayed by the delay time T of the delay element 7.

The delayed signal is output and also supplied to the multiplier 8. Multiplier 8 multiplies the delayed signal by a feedback coefficient g (+, 0<g<]), and the output signal of multiplier 8 is supplied to adder 6 and added to the input signal. Therefore, when the pulse signal aO is supplied as an input signal, the pulse signal aQ is output as is as shown in FIG. Signal a2 is output after delay time T has elapsed. By repeating this operation, the pulse signal a
Even after outputting 2, every time T elapses, 23, 84. a5...
A pulse signal is output, and the signal level gradually decreases.

The digital audio signal supplied to the input terminal IN is supplied to each comb filter 11 to 1°. Therefore, in each of the comb filters 11 to 1n, each sample value of the input digital audio signal is delayed by the respective delay times T1 to Tn, and thereafter, the signal level gradually decreases as each delay time elapses.

[Comb filter] Each output signal of 1 to 1° is sent to adder 2.
After being synthesized by APF3+ to 3m, it is further delayed. Since APF3+ to 3m have different group delay characteristics, the signal density increases by further delaying the output signal of adder 2. For example, in the case of impulse input, the sound level decreases over time, but the sound will continue.

Incidentally, the delay times T1 to Tn caused by the delay elements of the comb filters 11 to 1n are different from each other and are given as multiples of the sampling period. The number of samples corresponding to each delay time, ie, the number of delay samples, are made relatively prime.

For example, set the sampling frequency to 44. 1 [kHz
], the delay time T1 of the comb filter 11 is 1187 in the number of delay samples and 26. 9 [ms],
The delay time T2 of the comb filter 12 is 1367 in terms of the number of delay samples and 31. 0 [ms], < The delay time T3 of the L-shaped filter 13 is 154 in terms of the number of delay samples.
9.35 in time. 1 [mouth S]. Since the numbers of delay samples are made to be relatively prime in this way, the time it takes for the impulse responses of the comb filters 11 to 1n to overlap becomes very long. In the numerical values of the above example, the number of samples between the comb filters 11 and 12 is 1187×1367−1622629, and the time is 36.8 [s]. This value has a reverberation time of 2
Considering that it is within ~4 seconds, it means that the impulse responses do not substantially overlap.

Note that in the above-mentioned embodiments, the so-called hardware-configured device is shown, but the device is not limited to this, and a comb filter or AP
F may be configured by arithmetic processing.

As described above, the reverberation sound generation device according to the present invention has the following effects:
Since the number of samples corresponding to each delay time of the plurality of comb filters is made relatively prime, the impulse responses of the comb filters can be made to hardly match within the reverberation time. Therefore, the reverberant sound is evenly distributed without being temporally biased, and good reverberant sound quality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing the configuration of a comb filter, and FIG. 3 is a diagram showing the reverberation characteristics of the comb filter with respect to impulses. Explanation of symbols of main parts 11 to 1n...Comb filter 2...Adder 3 + ~3m = A P F 6...Adder 7...Delay element 8...Multiplier Applicant Pioneer Co., Ltd.

Claims (3)

[Claims] (1) A delay element that delays an input digital audio signal for each sample data, and a multiplication means that multiplies the delayed signal outputted from the delay element by a coefficient and returns the result to the input of the delay element, and outputs the delayed signal. A reverberation sound generation device comprising a plurality of comb-shaped filters, and an addition means for adding output signals of the plurality of comb-shaped filters, the number of samples corresponding to each delay time of the plurality of comb-shaped filters is A reverberation sound generation device characterized by being disjoint. (2) The reverberation sound generation device according to claim 1, further comprising an all-pass filter connected in cascade to the output of the adding means. (3) The reverberant sound generation device according to claim 1, wherein the delay time by the delay element is given as a multiple of a sampling period.