JPH0262875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reverberation adding device equipped with a delay circuit that achieves both reduction of coloration in the frequency domain and reduction of flutter echo in the time domain.

[Conventional technology]

As a conventional reverberation adding device, a comb filter type device is shown in FIG. 2a. A signal is input from an input terminal 1 and guided to an output terminal 3 via an adder circuit 2. The output signal is fed back via a feedback circuit 4. The feedback amount of the feedback circuit 4 is set to g. In the feedback circuit 4,
A delay circuit 5 with a delay time τ is inserted. The action of the delay circuit 5 produces reverberation in the output signal.

In the reverberation adding device shown in Fig. 2a, when a signal is input from input terminal 1, a second signal is input from output terminal 3.
A gradually attenuating reverberant signal is obtained as shown in Figure b. At that time, the transfer characteristic becomes as shown in FIG. 2c, and a sharp peak with a constant period appears. Because of this sharp peak, it is not possible to stably increase the open loop gain for the entire band. That is,
When the open loop gain is increased to near 1, these peaks grow preferentially compared to other bands, causing howling and coloration.

Since peaks occur at a period of 1/τ (Fig. 2c), increasing the delay time τ narrows the frequency interval at which peaks occur, making coloration less perceptible to the auditory sense. However, since the reverberation signal generation interval is τ (FIG. 2b), if the delay time τ is increased, the reverberation signal generation interval becomes longer, and an unnatural flutter echo will be felt. In other words, in the conventional reverberation adding device,
The disadvantage was that coloration reduction and flutter echo reduction could not be achieved at the same time.

[Problem that the invention seeks to solve]

This invention aims to solve the problems in the conventional techniques and achieve both reduction of coloration and reduction of flutter echo.

[Means for solving problems]

This invention provides a plurality of series of delay circuits with different delay times, applies an input signal to these in common, and feeds back a combined output of these delayed signals or a part of the output to the common input side. The output is extracted as a reverberant output signal.

[Effect]

According to the solving means of the present invention, by setting the delay time of each delay circuit to be long, it is possible to make coloration less perceptible, and by repeatedly using these delayed outputs as feedback, the reverberation signal is It is possible to relatively increase the generation density, that is, to shorten the interval between occurrences, and to prevent unnatural flutter echoes from occurring randomly, thus achieving both conflicting requirements with a simple configuration. .

Example 1 An example of the present invention is shown in FIG. In the circuit of FIG. 1, four delay paths 10, 12, 1
4 and 16 are provided in parallel. Each delay path 1
0, 12, 14, 16, delay circuits 18, 2
0, 22, 24 and attenuators 26, 28, 30, 32
are provided for each.

The signal is input from input terminal 1 and sent to adder circuit 3.
4 to the delay paths 10, 12, 14, and 16, respectively. Each delay path 10,1
The signals outputted from 2, 14, and 16 are added by an adder circuit 36 and guided to an adder circuit 44. Further, the output signal of the adder circuit 36 is added to the input signal in the adder circuit 34 via a feedback circuit 38. The signal input from the input terminal 1 is sent to the adder circuit 4 via a separate bypass path 42 in order to form a direct sound.
4 and each delay path 10, 12, 14, 1
6, and the output signal of this adder circuit 44 is led to the output terminal 3.

The delay times τ ₁ , τ ₂ , τ ₃ , and τ ₄ of the delay circuits 18, 20, 22, and 24 are relatively long and relatively close to each other, and satisfy the relationship τ ₁ <τ ₂ <τ ₃ <τ ₄ . Set in relationship.

Further, the mutual relationship among these delay times τ ₁ , τ ₂ , τ ₃ , and τ ₄ is set with appropriate irregularity so that the reverberant signals are generated at appropriately random positions.

Attenuation factors g ₁ of attenuators 26, 28, 30, 32,
g ₂ , g ₃ , and g ₄ are set to values such that g ₁ <g ₂ <g ₃ <g ₄ and a desired continuous attenuation characteristic of the reverberant signal as a whole can be obtained.

The operation of the circuit of FIG. 1 is shown in FIG. When a signal is input from the input terminal 1, this signal is directly output as a direct sound via the bypass path 42. After a time τ ₁ after this direct sound is output, a reverberation signal s ₁ is first output from the delay path 10. Similarly, after time τ ₂ , the reverberation signal s ₂ from the delay path 12 is
After time τ ₃ , the reverberant signal s ₃ is output from the delay path 14 at time τ ₄
Afterwards, the reverberant signals s ₄ are outputted from the delay path 16, respectively.

After that, these reverberant signals s ₁ to _{s 4} are sent to the feedback circuit 3
8 and returns to the adder circuit 34 on the input side,
A new reverberation signal is generated again.

That is, the time τ ₁ after the reverberation signal s ₁ is output
Afterwards, the reverberation signal _S11 is output from the delay circuit 10,
A reverberation signal s ₁₂ is output from the delay circuit 12 after τ ₂ , a reverberation signal s ₁₃ is output from the delay circuit 14 after τ ₃ , and a reverberation signal s ₁₄ is output from the delay circuit 16 after τ ₄ .
These reverberant signals s ₁₁ to _{s 14} are, when viewed from the direct sound,
The reverberation signals are output after times 2τ ₁ , τ ₁ +τ ₂ , τ ₁ +τ ₃ , and τ ₁ +τ ₄ . Also these reverberant signals s ₁₁
The attenuation rate of ~s ₁₄ is the direct sound, and the reverberant signal s ₁ ~s ₄
It matches the attenuation characteristic curve formed by.

_{Similarly, new reverberation signals s21 to s24 , s31 to s34 , s41} to
s ₄₄ is generated, and these second-order reverberation signals are then output as third-order reverberation signals, third-order reverberation signals, fourth-order reverberation signals, and so on, and so on, reverberation signals are output one after another. Therefore, the generation density of reverberant signals increases with time.

As described above, according to this configuration, the delay time itself of each delay circuit can be set relatively long.
As a result, coloration is reduced overall. In addition, the reverberant signal is used over and over again by the feedback loop, and the density of reverberant signal generation increases over time, and when viewed as a whole, the reverberant signal interval becomes sufficiently dense and random, and there is almost no occurrence of flutter echoes. .

FIG. 4 shows the transfer characteristics of the reverberation adding device shown in FIG. 1. It can be seen that the peaks and dips are flattened and the howling margin is also expanded.

Embodiment 2 In the embodiment shown in FIG. ₁ , as shown in FIG. This is observed.)
occurs. If this initial delay gap becomes too large, it will become an echo. Therefore, the embodiment shown in FIG.
This is to fill the delay gap. That is, the circuit of FIG. 5 includes delay paths 19, 21, and 23 in addition to the circuit of FIG.
The delay paths 19, 21, 23 are connected to delay circuits 25, 2
7 and 29, and attenuators 31, 33, and 35, respectively, and the input signal from the input terminal 1 is inputted thereto. The output signals of delay paths 19, 21, and 23 are added to the output signal in adder 37.

Delay times of delay paths 19, 21, 23 τ ₁ ′, τ ₂ ′,
τ ₃ ' are chosen such that their output signals are located several times in the initial delay gap.

The operation of the circuit of FIG. 5 is shown in FIG. Delay path 1 of the initial delay gap in Figure 3
It can be seen that the output signals 9, 21, and 23 are appropriately filled in with output signals s ₀₁ , s ₀₂ , and s ₀₃ . Note that the attenuator 31,
The attenuation rates g ₁ ′, g ₂ ′, and g ₃ ′ of 33 and 35 are set to match the attenuation characteristic curve of other reverberant signals.

Note that also in the embodiment shown in FIG.
If 2 is not provided, there will be no direct sound, so the initial delay gap can be eliminated.

Embodiment 3 In the embodiment shown in FIG. 7, whereas the one shown in FIG. It was designed to allow people to return home. That is, all the delay circuits 10 and 1 are connected to the adder circuit 36.
2, 14, and 16 output signals are added,
Only the output signal of the delay circuit 10 is fed back to the feedback circuit 38'. Incidentally, the direct sound from the input terminal 1 is separately inputted to the adding circuit 36 via a bypass path 42 and added thereto, similarly to the circuit shown in FIG.

According to this circuit, the generation density of the reverberant signal can be kept approximately constant regardless of time, and it is possible to prevent the generation density of the reverberant signal from increasing too much. can be similarly reduced.

Embodiment 4 In the embodiment shown in FIG. 8, the present invention is applied to a feedback loop including a room.

In FIG. 8, there is a speaker 48 in the room 46.
A microphone 50 is installed opposite to this. The output of the microphone 50 is transmitted via a head amplifier 52 to a delay path 10 connected in parallel.
12, 14, and 16, respectively. Each delay path 10, 12, 14, 16 includes a delay circuit 1
8, 20, 22, 24 and attenuators 26, 28, 3
0 and 32 are inserted respectively. Delay path 1
The output signals of 0, 12, 14, and 16 are sent to the adder circuit 5.
4 is added. Then, the output signal of the adder circuit 54 is transmitted to the power amplifier 5 inserted into the feedback circuit 56.
8 and is fed back to the speaker 48. Due to this feedback effect, reverberant sound is obtained from the speaker 48.

[Example of change]

In each of the above embodiments, one system has been described, but if a plurality of these systems are provided in parallel, more stable and audibly natural reverberant sound can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of delay circuits having different delay times are provided in parallel, an input signal is commonly applied to these, and all or a part of the combined output of the delayed outputs is applied to the input side. Since the configuration is configured to provide feedback to the reverberation signal, reverberation signals can be obtained with high generation density even if the delay time of each delay circuit is set long. Therefore, by increasing the delay time, it is possible to reduce coloration and expand the howling margin, and by increasing the density of reverberant signal generation, it is possible to reduce flutter echoes.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. FIG. 2 is a diagram showing a conventional reverberation adding device, in which a is a circuit diagram thereof, b is a line diagram showing an output reverberation signal, and c is a line diagram showing a transfer characteristic. Figure 3 shows
FIG. 2 is a waveform diagram showing an output reverberation signal of the reverberation adding device of FIG. 1; FIG. 4 is a diagram showing the transfer characteristics of the reverberation adding device shown in FIG. 1. FIG. 5 is a circuit diagram showing another embodiment of the invention. Figure 6 shows the fifth
FIG. 3 is a diagram showing an output reverberation signal of the reverberation adding device shown in the figure. FIGS. 7 and 8 are circuit diagrams showing still further embodiments of the present invention. 5, 18, 20, 22, 24, 25, 27, 2
9...Delay circuit, 10, 12, 14, 16, 1
9, 21, 23...delay path, 26, 28, 3
0, 31, 32, 33, 35...attenuator, 38,
38', 56...Feedback circuit.

Claims (1)

[Claims] 1. A plurality of delay circuits having different delay times are provided in parallel, an input signal is commonly applied to these delay circuits, and a combined output of these delayed output signals or a partial output thereof is fed back to the common input side of the delay circuits. , A reverberation adding device characterized in that the synthesized output is extracted as a reverberation signal.