JPH02170796A - Audio reproducing device - Google Patents

Abstract

PURPOSE:To prevent an indirect sound from being buried in a noise level even when a sound volume is lowered and to obtain a sufficient Hall acoustic effect by increasing the ratio of the transmission gain of an indirect sound signal to the transmission gain of a direct sound signal in a condition in which the level of the direct sound signal is level control operated so as to go to a prescribed value or below. CONSTITUTION:Variable resistors 35 and 38 are interlocked with a variable resistor 40 for an external operation, and by operating a sliding piece 40a of the variable resistor 40, sliding pieces 35a and 38a of the variable resistors 35 and 38 are moved, and the indirect sound signal and direct sound signal are both level-controlled. Here, in the condition in which the level of the direct sound signal is level-control-operated so as to go to the prescribed value or below, the ratio of the transmission gain of the indirect sound signal to the transmission gain of the direct sound signal is made high. Thus, even when the sound volume is lowered, the indirect sound cannot be buried in the noise level, and the sufficient Hall acoustic effect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement in an audio reproduction device for creating a pseudo sound effect in a reproduction room, for example, in a hall or the like.

(Prior Art) As is well known, when creating a simulated acoustic effect in a hall or the like in a reproduction room, the following means are used. That is, as shown in FIG. 9(a), the orchestra 13 is arranged on stage I2 of hall II, and the audience seats 14
It is assumed that you are listening at

Then, the listener 15 hears the reflected sound (indirect sound) 17 from the front and the reflected sound (indirect sound) 18 from the rear in addition to the direct sound 16, and a hall acoustic effect is obtained as a whole.

In order to simulate such a hall acoustic effect in the playback room, as shown in Figure 9(b), the direct sound 1B from the orchestra 13 is played back through the speakers 19 and 20, and the sound from the front is also played back. Indirect sound 17 to speaker 21.22
The indirect sound 18 from the rear is played back through the speakers 23 and 24.
By playing back the music and listening to it from the center audience seats 25, it is possible to give the listener 2G an acoustic effect as if he were listening in the hall 11.

Here, the direct sound and the indirect sound have a relationship as shown in FIG. 10. In FIG. 10, the horizontal axis is the time (1) axis, and it is assumed that an impulse sound is generated from the sound source at time 1-0. Then, the direct sound 27 reaches the listener after a delay time t1 corresponding to the spatial distance between the sound source and the listener has elapsed.

Next, the sound waves reflected from each reflecting surface of the hall reach the listener, and second and third-order reflected sounds that are further reflected from the reflected sounds arrive one after another. These reflected sounds have a delay time tl (n-1, 2...
...), which is collectively called indirect sound 2.
It is called 8.

Such indirect sound can be generated in the reproduction room by using the circuit shown in FIG. That is, the audio signal (direct sound) supplied to the input terminal 29 is given to the multistage delay circuit 30 and delayed by the delay time tO.
The signal SO~S+a of ~tm is multiplied by the coefficient ho-hIIl, added by the adder 31, and taken out from the output terminal 32. In this case, each coefficient hO to ha is the amplitude level of each indirect sound 28 shown in FIG.

As shown in FIG. 9(b), when the indirect sounds are reproduced by the four speakers 21 to 24, the delay is determined according to the respective propagation paths of the indirect sounds generated on the front left and right and rear left and right. The times tO to tI11 and the coefficients hO to hI11 are individually set.

Furthermore, in an actual reproduction room, the speakers 21 and 22 may be omitted, and the direct sound and the indirect sounds on the front left and right sides may be added and reproduced from the speakers 19 and 20. Furthermore, speaker 2
Not only 1.22 but also speakers 23.24 are omitted,
A simple system may be used that only gives a sense of spaciousness in the front. There is also a simplified method in which direct sound and indirect sound are added together and reproduced using one speaker, giving only a sense of reverberation. In addition to the circuit shown in FIG. 11, indirect sound generation means include mechanical means using springs and the like.

However, the following problems occur in the conventional audio playback device as described above. In other words, Fig. 12 (
a) shows a reproduction pattern of direct sound and indirect sound when the volume is sufficient, for example, the maximum volume (sound pressure level) of the direct sound is 1 ooas spt;

In this case, the indirect sound is well reproduced to the end, and a sufficient hall acoustic effect can be obtained.

However, as shown in Figure 12(b), the volume can be lowered to, for example, reduce the maximum volume (sound pressure level) of the direct sound to 70 dB.
When using SPL, if the background noise level in the reproduction room is 40 dB, most of the indirect sound will be buried in the background noise level, making it impossible to hear the indirect sound and making it impossible to obtain a sufficient hall acoustic effect.

(Problems to be Solved by the Invention) As described above, in the conventional audio playback device, when the volume is lowered, most of the indirect sound is buried under the noise level, and a sufficient hall acoustic effect cannot be achieved. have.

Therefore, this invention has been made in consideration of the above circumstances, and provides an extremely good audio reproduction device that can obtain sufficient hall acoustic effects without indirect sound being buried in the noise level even when the volume is lowered. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) An audio playback device according to the present invention includes a level control unit that controls the level of an input audio signal by external operation to generate a direct sound signal, and a level control unit that controls the level of an input audio signal by external operation to generate a direct sound signal, and a generation means for generating an indirect sound signal through signal processing including: a gain control means for controlling the transmission gain of the indirect sound signal output from the generation means based on a level control operation by the level control means; and a level control means. With the level control operated so that the level of the direct sound signal is below a predetermined value,
and control means for controlling the gain control means so as to increase the ratio of the transmission gain of the indirect sound signal to the transmission gain of the direct sound signal.

Furthermore, the audio playback device according to the present invention includes a level control unit that controls the level of an input audio signal by external operation to generate a direct sound signal, and a level control unit that performs signal processing including delay on the input audio signal to generate an indirect sound signal. a generation means, a gain control means for controlling the transmission gain of the indirect sound signal outputted from the generation means based on a level control operation by the level control means, and a level of the direct sound signal outputted from the level control means set to a predetermined value. and control means for controlling the gain control means so as to increase the ratio of the transmission gain of the indirect sound signal to the transmission gain of the direct sound signal under the following conditions.

Furthermore, the audio playback device according to the present invention includes level control means for controlling the level of an input audio signal by external operation to generate a direct sound signal, and processing the input audio signal including a delay to generate an indirect sound signal. Based on the generation means and the level control operation by the level control means,
gain control means for controlling the transmission gain of the indirect sound signal output from the generation means; and a transmission gain of the indirect sound signal relative to the transmission gain of the direct sound signal in a state where the transmission gain of the direct sound signal is controlled to a predetermined value or less. and control means for controlling the gain control means so as to increase the ratio of the gain control means.

(Function) According to the above configuration, when the level control means performs the level control operation such that the level of the direct sound signal is below a predetermined value, the level of the direct sound signal output from the level control means is set to the predetermined value. The ratio of the transmission gain of the indirect sound signal to the transmission gain of the direct sound signal is increased when the transmission gain of the direct sound signal is controlled to be below a predetermined value, or when the transmission gain of the direct sound signal is controlled to be below a predetermined value. Even if the noise level is lowered, indirect sound will not be buried under the noise level, and a sufficient hall acoustic effect can be obtained.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In FIG. 1, an audio signal supplied to an input terminal 33 is supplied to an indirect sound generation circuit 34 having the configuration shown in FIG. 11, for example, to generate an indirect sound signal. This indirect sound signal is level-controlled by a variable resistor 35 and then taken out from an output terminal 37 via a variable gain amplifier 36. Further, the audio signal supplied to the input terminal 33 is level-controlled by a variable resistor 38, and is outputted from an output terminal 39 as a direct sound signal.

Here, the variable resistors 35 and 38 are linked with a variable resistor 40 for external operation, and by operating the slider 40a of this variable resistor 40, the variable resistors 35 and 38 are operated.
38 sliders 35a and 38a are moved so that the levels of both the indirect sound signal and the direct sound signal are controlled.

Further, a constant voltage source 41 is connected to both ends of the variable resistor 40. Therefore, the slider 40 of the variable resistor 40
From a, a control voltage vffl corresponding to the position, that is, the control level of the indirect sound signal and the direct sound signal is obtained. The control voltage v11 obtained from the slider 40a of the variable resistor 40 is applied to the non-linear circuit 4.
2 and used to generate a control voltage Vc to be applied to the variable gain amplifier 36.

Here, the variable gain amplifier 36 has a gain G of G-exp (Vc/VT), where VT is a constant. In addition, the relationship between the input control voltage v11 and the output control voltage Vc of the nonlinear circuit 42 is as follows.
It is as shown in Figure 2. In FIG. 2, the input control voltage v11 and the attenuation amounts of the indirect sound signal and the direct sound signal are shown in correspondence on the horizontal axis.

That is, this non-linear circuit 42 has an attenuation amount of OdB to -
In the range of 20 dB, the output control voltage Vc is Ov, and the gain G of the variable gain amplifier 36 is "1". Therefore, the indirect sound signal whose level has been controlled by the variable resistor 35 is taken out from the output terminal 37 as it is. Furthermore, when the attenuation amount becomes less than 120 dB to -30 dB, the nonlinear circuit 42 increases the output control voltage Vc by a level corresponding to increasing the gain G of the variable gain amplifier 36 by 10 dB. Therefore, the indirect sound signal whose level has been controlled by the variable resistor 35 is amplified by 1 odB by the variable gain amplifier 36 and taken out from the output terminal 37.

According to the above configuration, as shown in FIG. 12(b), when the volume is lowered to make the maximum volume (sound pressure level) of the direct sound 70 dB SPL, the indirect sound signal is variable. Since it is amplified by 10 dB by the gain amplifier 36, the third
As shown in the figure, the sound is higher than the background noise level (40 dB) and is reproduced without being buried in the background noise level, so that a sufficient hall acoustic effect can be obtained.

FIG. 4 shows a second embodiment of the invention. That is, to explain by attaching the same symbols to the same parts as in FIG. 1, the indirect sound signal output from the indirect sound generation circuit 34 is taken out from the output terminal 37 via the variable gain amplifier 43. Furthermore, the audio signal supplied to the input terminal 33 is taken out from the output terminal 39 as a direct sound signal via the variable gain amplifier 44.

The control voltage Vl obtained from the slider 40a of the variable resistor 40 becomes the control voltage of the variable gain amplifier 44 as it is, and is also supplied to the nonlinear circuit 45 to generate the control voltage Vc to be applied to the variable gain amplifier 43. be done. Therefore, by moving the slider 40a of the variable resistor 40, the control voltage Vl changes, and accordingly, the gain of the variable gain amplifiers 43 and 44 changes, and the indirect sound signal and the direct sound signal are Level can be controlled.

In this case, the amount of attenuation of the variable gain amplifier 44 is changed linearly with respect to the amount specified by the position of the slider 40a of the variable resistor 40, as shown in FIG. 5A. On the other hand, the attenuation amount of the variable gain amplifier 43 is as shown in FIG. 5B.
The indicated amount indicated by the position of the slider 40a of the variable resistor 40 has the same characteristics as the variable gain amplifier 44 from OdB to -20 dB, but the indicated amount ranges from 120 dB to -30 dB.
When it becomes less than LOdI3 due to the action of the non-linear circuit 45,
It is possible to obtain the same effect as in the above embodiment.

FIG. 6 shows a modification of the second embodiment, in which the audio signal supplied to the input terminal 33 is
The signal is supplied to the variable gain amplifier 44 via a compensation circuit 46 that weights signals in the range of 1 kHz to 10 kHz.

Further, the control voltage vI11 supplied to the variable gain amplifier 44 and the nonlinear circuit 45 is not limited to being obtained only from the variable resistor 40 and the constant voltage source 41, but also from the up key 47 and the down key as shown in FIG. 48 may be selectively operated to cause the counter 49 to perform an up or down count operation, and the output of this counter 49 may be supplied to the D/A (digital/analog) converter 50 to obtain the control voltage v11. good.

FIG. 8 shows a third embodiment of the present invention, in which the levels of indirect sound signals and direct sound signals are controlled by digital signal processing. That is, the digital audio data supplied to the port 51 is converted into digital indirect sound data by the digital indirect sound generation circuit 52, and then level-controlled by the digital multiplier 53 and output. Furthermore, the digital audio data supplied to the boat 51 is level-controlled by a digital multiplier 54 and output as digital direct sound data.

On the other hand, the up key 55 and down key 56 are selectively operated to cause the counter 57 to perform an up or down count operation, and the output of the counter 57 is stored in a ROM (read only memory) 58. 59 address. Among these, the ROM 59 stores a coefficient data table to be supplied to the digital multiplier 54 in correspondence with the output of the counter 57. This coefficient data table is set so that the amount of attenuation by the digital multiplier 54 with respect to the instruction amount specified by the output of the counter 57 has the characteristics shown in FIG. 5A.

The ROM 58 also stores a coefficient data table to be supplied to the digital multiplier 53 in correspondence with the output of the counter 57. This coefficient data table is based on counter 5
The amount of attenuation by the digital multiplier 53 with respect to the instruction amount specified by the output of 7 is set to have the characteristics shown in FIG. effect can be obtained.

It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As detailed above, the present invention provides an extremely good audio playback device that can obtain sufficient hall acoustic effects without indirect sound being buried in the noise level even when the volume is lowered. can do.

[Brief explanation of the drawing]

FIG. 1 is a block circuit configuration diagram showing an embodiment of an audio playback device according to the present invention, FIG. 2 is a characteristic diagram of a non-linear circuit of the embodiment, and FIG. 3 is for explaining the effects of the embodiment. , FIG. 4, and FIG. 5 are block circuit configuration diagrams showing a second embodiment of the present invention and characteristic diagrams for explaining its operation, and FIG. 6 is a modification of the second embodiment. FIG. 7 is a block circuit diagram showing a modification of the level control operation means of the first and second embodiments, and FIG. 8 is a block circuit diagram showing a third embodiment of the invention. Fig. 9 is a diagram for explaining the concept of obtaining a hall acoustic effect in a reproduction room, Fig. 10 is a diagram showing the relationship between direct sound and indirect sound, and Fig. 11 is a diagram showing the indirect sound generating means. The block configuration diagram shown in FIG. 12 is a diagram for explaining the conventional problems. 11... Hall, 12... Stage, 13... Orchestra, 14... Audience seats, 15... Listener, 16
...Direct sound, 17, 18...Indirect sound, 19-24.
... Speaker, 25 ... Audience seat, 26 ... Listener, 2
7... Direct sound, 28... Indirect sound, 29... Input terminal, 30... Multi-stage delay circuit, 31... Adder, 32
... Output terminal, 33... Input terminal, 34... Indirect sound generation circuit, 35... Variable resistor, 36... Variable gain amplifier, 3... Output terminal, 38... Variable resistor, 39... Output terminal, 40... Variable resistor, 41.
...constant voltage source, 42...nonlinear circuit, 43, 44...
・Variable gain amplifier, 45...nonlinear circuit, 4B...
Compensation circuit, 47... Up key, 48... Down key 49... Counter, 50... D/A converter, 51
...Port, 52...Digital indirect sound generation circuit, 5
3.54...Digital multiplier, 55...Up key 56...Down key 57...Counter, 58.5
9...ROM0 Applicant's agent Patent attorney Takehiko Suzue Figure Figure Figure Figure Vcc Funeral Figure Figure Figure BSPL (a) (b) Figure

Claims (3)

[Claims] (1) Level control means for controlling the level of an input audio signal by external operation to generate a direct sound signal, generation means for processing the input audio signal including delay to generate an indirect sound signal, and the level control gain control means for controlling the transmission gain of the indirect sound signal output from the generating means based on the level control operation by the means; and a control means for controlling the gain control means so as to increase the ratio of the transmission gain of the indirect sound signal to the transmission gain of the direct sound signal in a controlled state. Device. (2) Level control means for controlling the level of an input audio signal by external operation to generate a direct sound signal; generation means for processing the input audio signal including a delay to generate an indirect sound signal; and the level control gain control means for controlling the transmission gain of the indirect sound signal output from the generation means and the level of the direct sound signal output from the level control means on the basis of a level control operation by the means; and control means for controlling the gain control means so as to increase the ratio of the transmission gain of the indirect sound signal to the transmission gain of the direct sound signal in the above state. (3) level control means for controlling the level of an input audio signal by external operation to generate a direct sound signal; generating means for processing the input audio signal including a delay to generate an indirect sound signal; and the level control gain control means for controlling the transmission gain of the indirect sound signal output from the generating means based on the level control operation by the means; 1. An audio playback device comprising: control means for controlling the gain control means so as to increase the ratio of the transmission gain of the indirect sound signal to the transmission gain of the sound signal.