JPS6060073B2 - Reverberation adding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention calculates the autocorrelation coefficients of an input signal in a reverberation adding circuit of a stereo device, karaoke device, etc. The present invention relates to a reverberation adding device that attempts to obtain an optimal reverberation effect corresponding to an input signal by changing the level ratio between reverberant sound and direct sound in an additional circuit.

Conventional examples include those that change the delay time or level ratio of the reverberation adding circuit depending on the level of the input signal, and those that change the delay time or level ratio of the reverberation adding circuit depending on the magnitude of the autocorrelation coefficient at a certain delay time of the input signal. There are things that change time.

Among the factors that cause people to feel a sense of reverberation, the one that causes the greatest psychological change is when the level ratio between the input signal and the delayed signal is changed.

On the other hand, it is well known that the physical characteristics of a sound source signal can be quantified by the autocorrelation number, and it has been reported that reverberation is related to the autocorrelation number of the sound source in subjective evaluation in a sound field. . The autocorrelation number of the sound source is generally the first
The trend shown in the figure is shown.

Now, find the autocorrelation coefficient F at a certain delay time Tl. If the coefficient is large, the correlation with the original signal is high, so the reverberation is increased accordingly. Conversely, if the coefficient is small, the correlation with the original signal is low, so reverberation is reduced. Changing the reverberation addition amount in accordance with the magnitude of the correlation number in this way has physical meaning, and can be used as a reverberation effect. FIG. 2 shows a general reverberation adding circuit.

Input signal 1 enters adder 6 as direct sound signal 2. At the same time, the delayed signal 3 that has passed through the delay circuit 7 is sent to the attenuator 9 and fed back through the attenuator 8. Then, the direct sound signal 2 and the delayed signal 4 passed through the attenuator 9
are added in the adder 6 and the reverberation is added to the output signal 10.
is obtained. Note that 5 is an adder. The present invention is a development of the reverberation adding circuit shown in FIG. 2, and one embodiment thereof will be described below along with FIG. 3, with the same numbers assigned to the same parts as in FIG. 2.

The present invention has an autocorrelation coefficient calculation circuit 1 as shown in FIG.
1 to obtain the autocorrelation coefficient of the input signal 1, and change the amount of attenuation of the attenuator 9 by using the level ratio control signal voltage 12 according to the magnitude thereof.

In this case, the amount of attenuation of attenuator 9, which has the greatest effect on reverberation, was changed, but the amount of attenuation of attenuator 8 may be changed at the same time. FIG. 4 shows an embodiment of the autocorrelation coefficient calculation circuit 11.

That is, the autocorrelation coefficient at a certain delay time τ1 of the input signal 1 can be obtained by multiplying the direct sound signal 2 by the delayed signal 17 passed through the delay circuit 14, and averaging the results in the averaging circuit 15. If multiple delay times are required due to the characteristics of the input signal 1, τ, , τ2 . . . τ as shown in Fig. 4. It is sufficient to provide a plurality of , and find the autocorrelation coefficient for each.
13″, ..., 13n are multipliers, 1C, ..., 14
n is a delay circuit, and 17'', . . . , 17n are delay signals.

Then, the magnitude of the autocorrelation coefficient of the obtained input signal 1 is computed by the arithmetic circuit 16 and converted into a level ratio control signal voltage 12 corresponding to the magnitude. The above calculation circuit 16
Then, the following calculation can be considered. For example, the added value,
These include an average value, a peak value, and a weighted value. Also,
Time constant Tl of average circuit 15, 15″, ..., 15n
, T2, . . . , Tn are determined by the characteristics of the input signal 1 and the values of the delay circuits 14, 1', . . . , 14n. As mentioned above, Fig. 4 shows an example of an analog autocorrelation coefficient calculation circuit, but it is also possible to use a direct sound signal 2
A unipolar autocorrelation coefficient calculation circuit in which only one of the and delayed signals 17 is made into a zero-crossing wave, a bipolar autocorrelation coefficient calculation circuit in which both are made into zero-crossing waves as shown in Fig. 5, and furthermore, a digital computer is used. It can be achieved even if

In Fig. 5, 18 and 18'' are zero cross wave forming circuits, 1
9 is a logic circuit. FIG. 6 shows an example of the relationship between the magnitude of the autocorrelation coefficient of the sound source and the level ratio (=delayed signal/input signal) of the reverberation adding circuit.

In actual use, it is more effective to change the amount of reverberation at a constant value up to a certain correlation coefficient, such as Y2, and to use a nonlinear relationship beyond that, rather than using a linear or nonlinear relationship for y1. When this device of the present invention is used in a reverberation adding circuit for a stereo or karaoke device, a large amount of reverberation is automatically added where the autocorrelation coefficient of the input signal is large, and a small amount of reverberation is automatically added where the autocorrelation coefficient is small. Because
It is possible to obtain a reverberation effect that is more comfortable for both the person singing and the person listening than a fixed amount of reverberation as a sound effect.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing an example of the autocorrelation coefficient of a sound source.
The figure is a block diagram of a general reverberation adding circuit, FIG. 3 is a block diagram showing an embodiment of the reverberation adding device according to the present invention, and FIGS. 4 and 5 are autocorrelation coefficient calculations that constitute the device. FIG. 6 is a block diagram showing each embodiment of the circuit, and FIG. 6 is a characteristic diagram showing an example of the relationship between the magnitude of the autocorrelation coefficient of the sound source and the level ratio of the reverberation adding circuit for explaining the present invention.

Claims (1)

[Claims] 1. In a circuit that forms a reverberated sound by adding an input signal and a signal obtained by feeding back a delayed signal obtained by delaying this input signal, the autocorrelation number of the input signal is calculated, and a certain one Alternatively, the level ratio between the input signal and the feedback-applied delayed signal may be set to a linear relationship, a non-linear relationship, or a linear + non-linear relationship, depending on the magnitude of the autocorrelation coefficient at multiple delay times. A reverberation adding device characterized by changing the reverberation.