JPS638480B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reverberation adding device that adds a reverberation sound effect to an audio signal.

As an example, if the sound receiving point is set far away from the sound source in a sound field such as a listening room, and an impulse sound (sound of hand clapping, paper pistol, etc.) is generated as the sound source, a large level of direct sound is generated as shown in Figure 1. The sound consisting of the arriving sound and the reflected sound that occurs subsequently and gradually attenuates is picked up. This attenuation curve is a substantially exponential curve.

However, in the case of a large hall, there is an initial delay time between the directly arriving sound and the reflected sound reflected from the walls, ceiling, etc., and it is within this initial delay time that the reflected sound from the floor arrives. There are cases where Also,
If there is a large reflective surface near the sound source, the attenuation curve will not be a smooth curve as shown in FIG. 1, but will have undulations along the way.

In consideration of the above points, the present invention aims to provide a reverberation adding device that can generate various reverberation sound effects, such as generating sound effects that are closer to the actual sound field. .

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, 1 indicates a reverberation adding unit. The reverberation addition unit 1 is made of iron plate,
Any structure may be used, such as one that uses mechanical vibrations such as a spring, one that uses an analog delay line made of a charge transfer element, or one that performs digital processing (delay or calculation). As an example, in the case of a configuration that performs digital processing, Figure 3A
It is made by combining multiple basic configurations as shown in the figure below. In other words, the delay circuit 12 with a time T
, a multiplier 13 that multiplies input data by a coefficient k (0<k<1), and an adder 14 to form a basic configuration. As shown in Figure 3B,
When input data with a level of 1 is added, k output data appear at time intervals of T, and thereafter k ² , k ³ , . . . appear sequentially as output data at intervals of T. Therefore, by choosing the value of k, it is possible to form reverberant sound data that decreases exponentially with respect to certain input data. However,
In the configuration shown in FIG. 3A, since T is constant, echo sound data is obtained. Therefore, in order to approximate the actual reverberation, it is necessary to shorten T as the sound is attenuated. For this reason, reverberant sound data is created by combining a plurality of basic configurations shown in FIG. 3A and selecting values of delay time T and coefficient k for each of the basic configurations.

When the reverberation adding unit 1 is of the digital type as described above, input data obtained by PCM modulating the audio signal is supplied to the input terminal 2. Input data is supplied to the first delay circuit 3. The delay amount of this delay circuit 3 is the initial delay time
is chosen equal to T ₀ . The output of this delay circuit 3 is supplied to a second delay circuit 4 and an adder 5. The adder 5 receives the output of the delay circuit 4 from the multiplier 6.
A level-adjusted signal is also added. Multiplier 6 is supplied with a desired coefficient from terminal 7 .
The output of the adder 5 is then supplied to the reverberation adding unit 1 as input data. Output data from the reverberation addition unit 1 is supplied to an adder 8. Furthermore, input data whose delay amount is smaller than the total delay amount of the delay circuit 3 is level-adjusted by a multiplier 9 and supplied to an adder 8 . Multiplier 9 is supplied with a desired coefficient from terminal 10 . Then, output data to which the reverberation sound effect has been added appears at the output terminal 11 of the adder 8. A D/A converter and a low-pass filter may be connected to this output terminal 11 to return the signal to an audio signal.

In one embodiment of the present invention having the above-described configuration, the output when impulse sound is supplied is as shown in FIG. 4. A reverberant sound effect having an attenuation curve indicated by _P1 is generated from a position delayed by an initial delay time _T0 with respect to the directly arriving sound _R0 . Further, a delayed sound R ₁ corresponding to the reflected sound from the floor is generated after being delayed from the directly arriving sound R ₀ by a time T ₁ determined at the position where the signal is taken out from the delay circuit 3 . Furthermore, from a place delayed by time T ₂ with respect to the directly arriving sound R ₀ ,
A reverberant sound effect with a decay curve indicated by P ₂ is generated. The delay time of the delay circuit 4 is (T ₂ −T ₀ ). The ratio of the magnitude of the directly arriving sound R ₀ and the delayed sound R ₁ is:
It is determined by the coefficient for multiplier 9. In the case shown in FIG. 4, the coefficient for the multiplier 6 is set to 1.

As understood from the description of one embodiment above,
According to the present invention, by controlling the delay time of the delay circuit 4 and the level of its delayed output, it is possible to create a reverberant sound effect whose attenuation curve is not smooth but has ups and downs along the way. Therefore, it is possible to simulate a reverberant sound effect in a sound field that has a large reflective surface such as a wall near the sound source. Furthermore, it is possible to create a reverberant sound effect that hardly exists in reality. In short, it becomes easier to create a desired reverberant sound effect.

FIG. 5 shows another embodiment of the invention. In this example, the first and second delay circuits are connected in parallel, and separate reverberation adding units 1A and 1B are provided. If the reverberation adding unit is provided separately, not only the level but also the reverberation time and the like can be set separately for the reverberation curves _P1 and _P2 .

Note that although not shown, the delay circuit 4 in FIG.
A third delay circuit may be further connected to the reverberation sound effect to synthesize three types of reverberation sound effects. Further, when performing digital processing, it is also possible to use a RAM (random access memory) as a delay circuit, and furthermore, to share this RAM with the RAM in the reverberation adding unit 1, and to perform digital arithmetic processing according to a predetermined program.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram used to explain the reverberant sound effect, Figure 2 is a block diagram of an embodiment of the present invention, and Figure 3A.
and B are a block diagram and a schematic diagram used to explain the reverberation adding unit, FIG. 4 is a schematic diagram used to explain one embodiment of the present invention, and FIG. 5 is a block diagram of another embodiment of the present invention. be. 1, 1A, and 1B are reverberation adding units, 2 is an input terminal, 3 is a first delay circuit, 4 is a second delay circuit, and 11 is an output terminal.

Claims (1)

[Claims] 1. Obtain a first signal delayed by a time corresponding to the initial delay time and a second signal delayed by a time longer than this initial delay time, and
A reverberation adding device is configured to form a reverberation sound effect based on the first and second signals by supplying each of the signals to a reverberation adding unit.