JP2548103B2 - Sound reproduction device - Google Patents

Description

The present invention relates to a sound reproducing device configured to apply a sound signal to speakers arranged in front of and to the left of a listener, and particularly to a listener from an arbitrary direction and distance other than an actual speaker position. It is an object of the present invention to provide a sound reproducing device capable of perceiving sound and providing various sound field feelings.

Generally, when the sound signals are commonly input to the speakers arranged on the left and right sides of the front of the recipient and the reproduced sound image from the left and right speakers is perceived at an arbitrary position other than the left and right speaker positions, the left and right speakers are input. A control system including an equalizer was provided in the signal transmission line of. However, conventionally, as a means for realizing the above-mentioned equalizer, since the control method for changing the Bode type amplitude frequency characteristic and the method using the combination of the phase shifter or the single delay are used,
The waveform when the virtual speaker is sounded in both ears of the listener is difficult to be reproduced correctly, and thus there is a drawback that it is difficult to obtain a satisfactory effect.

As an example of a configuration for solving such a drawback, as shown in FIG. 1, a convolution equalizer (hereinafter referred to as a convolver) including a convolution integration circuit is provided in the signal transmission path to the left and right speakers, and There is a sound reproduction device that can reproduce a faithful sound image and sound quality by correctly reproducing the target waveform in both ears.

In FIG. 1, 1 is an input signal input terminal, 2 and 3 are convolvers, 4 and 5 are left and right speakers, 8 is a virtual speaker, and 9 is a listener. The above convolvers 2 and 3 are second
As shown in the figure, the input signal applied to the input terminal 11 is passed through a delay device 12 in which a plurality of delay elements 12-1, 12-2 ... Delay element
Outputs from 12-1, 12-2, ...
1, 13-2 ... 13-n are added in the adder 14 and output to the output terminal 15. The convolvers 2 and 3 can set the impulse response of the convolver to an arbitrary waveform by arbitrarily setting the coefficients of the coefficient units 13-1, 13-2 ... 13-n.

Therefore, the method for obtaining the coefficient of each coefficient unit will be described below.

In FIG. 1, the convolvers 2 and 3 have m stages,
Each tap coefficient And

In addition, the measured values obtained by sampling the transmission impulse responses from the speakers 4,5 to the ears 6 and 7 of the listener 9 with the delay time between taps of the convolver And then, h _{[phi] r =} In the same manner a response from the loudspeaker 8 to the binaural 6,7 of the listener _{9 (h φr1, h φr2,} ...... h φrn) h φl = (h φl1, h φl2, ...... h φln ) …… (3)

Now, when an impulse is input to the input terminal 1 in FIG. 1, a signal resulting from the convolution operation of the convolver coefficient and each transmitted inbals response is generated in the ears 6 and 7 of the listener 9.

In other words, as an impulse response of both ears And Equation (5) is And then g = Hx (7). The h _φr, 0 m-1 pieces of each of h _Faieru
Is added to define the following.

Here, the evaluation function P is defined as the degree of approximation to g.

Here, in order to find x that minimizes P, partial differentiation with x Therefore, H ^T Hx = H ^T Therefore, x = (H ^T H) ^-1 H ^T ... (10)

Therefore, the coefficients of x _r and x _l , which are the elements of x, are
By setting the coefficient unit of
It is possible to synthesize impulse responses in both ears 6, 7.

Next, an embodiment of the present invention in which the number of taps is reduced as compared with the sound reproducing device shown in FIG. 1 will be described below.

FIG. 3 is a block diagram showing the configuration of the sound reproducing device in one embodiment of the present invention. In FIG. 3, reference numeral 1 is an input signal input terminal, 22 is a convolver having m stages, 23 is a convolver having k stages, and 4,5 are left and right speakers. As shown in FIG. 4, the convolver 22 passes the input signal from the input terminal 1 through a delay device 31 in which m delay elements 31-1, 31-2, ... -1, 31-2 ... 31
The output from -m is the coefficient unit 32-1, 32-2 ... 32-
It is configured such that total addition is performed by the adder 33 via m and is added to the left speaker 4. The convolver 23 outputs the output of the convolver 22 to k delay elements 35-1, 35-2, ... 35-.
Each of the delay elements 35-1, 35 is passed through a delay device 35 in which k is connected in cascade.
-2 ... Outputs from 35-k are converted into coefficient units 36-1, 36-, respectively.
2 ... 36-k is used for total addition by an adder 37 and adding to the right speaker 5.

In FIG. 3, the convolver 22 is the same as the convolver 2 of FIG. 1, but the convolver 23 differs from the convolver 3 of FIG. 1 in the number of stages and coefficient values. Here, the coefficient of the convolver 23 in FIG. 3 is k (k <m), and the coefficient is x _c .
Since the coefficient of the convolver 22 is x _r , the output of the convolver 23 when an impulse is input to the input of the input terminal 1 is x _r
It can be expressed by the convolution operation of x _c . This operation is expressed by a matrix, and the impulse response output of the convolver 23 is (d ₁ , d ₂ ...... d
_{m + k-1} ) Next _D = x D x _C Distant, whereas x _l matrix by adding a k-1 zeros in U And the approximation degree of D to U is defined as an evaluation coefficient q as follows.

It is differentiated by x _C to determine the x _C to the q minimize Then, X _D ^T X _D X _C = x _D ^T U is obtained, and X _C = (X _D ^T X _D ) ^-1 x _D ^T U is obtained.

By setting this X _C in the convolver 23, the effect equivalent to that in FIG. 1 can be realized with a smaller number of taps.

To specifically set the coefficients of the convolvers 22 and 23, a microcomputer 19 for setting the coefficients in a coefficient unit composed of a multiplication DA converter, a storage circuit 20 for preliminarily storing speaker data at positions such as the virtual speaker 8 and the like. By including the above, data in various directions can be set from the memory circuit 20 to each coefficient unit, and various common functions can be provided by a common convolver. By converting the convolver connection into the common part and the difference part in this way, the number of stages of the convolver in the difference part can be reduced, and the cost can be reduced by simplification.

As described above, according to the present invention, by the configuration in which the first convolution equalizer and the second convolution equalizer circuit are cascaded, it is possible to reduce the number of taps of the second convolution equalizer and the listener. This has the advantage that the target waveform can be correctly reproduced in both ears and that the listener can surely perceive a sound image according to the waveform.

[Brief description of drawings]

FIG. 1 is a block diagram of a sound reproducing device using a convolution equalizer, FIG. 2 is a block configuration diagram of a main part of the device, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. It is the specific circuit diagram. 2,3 ... Convolver, 22,23 ... Convolver, 4,5 ... Speaker.

Claims (1)

(57) [Claims] 1. A first convolution equalizer that performs a convolution operation on an acoustic input signal, a second convolution equalizer that inputs the output of the first convolution equalizer, and a first convolution equalizer output. A first speaker for inputting, a second speaker for inputting the second convolution equalizer output, and a coefficient setting circuit for setting coefficients of the first and second convolution equalizers, the coefficient The setting circuit includes an impulse response from the first speaker to the listener's right ear h _Rr , an impulse response from the first speaker to the listener's left ear h _Rl , and a listener from the second speaker. Impulse response to the right ear of
h _Lr , h _Ll the impulse response from the second speaker to the listener's left ear, h _φr the impulse response from the speaker at any direction and distance to the listener's right ear, also to the listener's left ear h _Rr = the impulse response as _h φl of _{[h Rr1, h Rr2, ...} , h Rrn] h Rl = [h Rl1, h Rl2, ..., h Rln] h Lr = [h Lr1, h Lr2, ..., h _{Lrn] h Ll = [h Ll1} , h Ll2, ..., h Lln] h φr = [h φr1, h φr2, ..., h φrn] h φl = [h φl1, h φl2, ..., and _h φln], When defined as The elements of the matrix x _r represented by are set to the coefficients of the first convolution equalizer, and x _C = (from the matrix x _D obtained from the elements of x _{r and} the matrix U obtained from x _l shown below. x _D ^T x _D ) ^-1 x _D ^T U The element of the matrix x _C is set to the coefficient of the second convolution equalizer, and the sound reproducing device is characterized.