JPS58201499A - Controller of sound image - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound image control device for controlling a reproduced sound image from speakers placed on the left and right sides of a horizontal plane including a listener, and in particular, the present invention relates to a sound image control device for controlling a reproduced sound image from speakers placed on the left and right sides of a horizontal plane including a listener.
The sound image can be controlled independently within the range of 0,
It is an object of the present invention to provide a sound image control device that can localize a sound image at an arbitrary position.

In general, when an acoustic signal is commonly input to speakers placed in front of the listener on the left and right, and when controlling and localizing the reproduced sound image from the speakers to an arbitrary position, the acoustic signal input to the left and right speakers is A convolution equalizer (hereinafter simply referred to as a convolver) configured to total the outputs from the delay devices each having a single delay element connected in cascade through a coefficient unit is inserted in parallel, and the sound is output from the left and right speakers. The transmission characteristics in both ears of the listener when sound is emitted are made to approximate the transmission characteristics in both ears of the listener when sound is emitted from one speaker placed at an arbitrary position. This allows the listener to feel as if the sound is being radiated from a speaker placed at an arbitrary position. By changing the tap coefficients of the convolver, the sound image can be controlled independently within the range of 180° in the vertical direction and 36o0 in the horizontal direction of the listener, and the sound image can be localized at any position.

FIG. 1 shows a conventional sound image control device. In Figure 1,
1 is memory, 2 is decoder, 3 is joystick, 4
5 and 6 are input terminals, 5 and 6 are convolvers, 7 and 8 are speakers placed in front and left and right of the listener, 9 is a virtual speaker placed at an arbitrary position, and 1o is the listener. In such a configuration, the memory 1 stores the values of the tap coefficients of the convolvers 6 and 6 and the tap coefficients of the convolvers 5 and 6 at the position of an arbitrary sound image to be synthesized, and the joystick 3 is used to select the sound image to be synthesized. The position of the sound image is controlled by specifying the position of the sound image, detecting the tap coefficient corresponding to the position of the sound image from the memory 1 by the decoder 2, and outputting the data 2 to the convolver 6.6.

FIG. 2 shows the position of the listener and the sound image to be localized. In FIG. 2, the x mark indicates the position of the sound image, and 11 indicates the sound image 12 at eo0 above the median plane relative to the listener 17.
13 is a horizontal plane including both ears of the listener,
16 is shown on a horizontal plane including the point of the sound image 16 at 6o0 below the median plane of the listener, and the positions of each sound image are set at 45° intervals on each horizontal plane, and there are 24 points in total.

However, when localizing a sound image at such a position, if the conventional sound image control device described above is used, tap coefficients of the convolvers 5 and 6 are required for each of the 24 sound image positions, and the memory 1 is required to correspond to the tap coefficients. Since the amount of information recorded in the memory is required, the number of memories 1 is required for the number of sound images to be controlled, and the disadvantage is that the number of memories 1 must increase as the number of sound images to be controlled increases. .

The present invention eliminates the above-mentioned drawbacks of the conventional technology and independently controls the sound image in the vertical direction of the listener at 18o0 and in the horizontal direction at 3600°, thereby significantly reducing the number of memories and localizing the sound image at an arbitrary position. It is configured so that it can be

The present invention will be described below with reference to drawings of embodiments.

FIG. 3 shows an embodiment of the present invention. In FIG. 3, 18 is a memory, 19 is a decoder, 20, 21 is a joystick, 22 is a convolver for vertical direction control, 2
3 is a convolver for horizontal direction control; 24, 25 are speakers placed on the left and right in front of the listener; 26 is a virtual speaker placed at the position of point P; 27 is the listener; and 28 is an input terminal.

In such a configuration, joystick 2o or 2
1 specifies the position of the sound image in the horizontal direction, and specifies the position of the sound image in the vertical direction with the joystick 21 or 20.
By detecting the tap coefficients of the convolvers 22 and 23 corresponding to the position of the sound image of 8 and outputting them to each convolver 22 and 23, the sound image can be localized to an arbitrary position.

In the above-mentioned sound image control device, hRY + hnQ,
is the response in both ears when an impulse is input to the right speaker 24, hLQ and hLr are the responses in both ears when an impulse is input to the left speaker 25, and h4
．． h2 is the response of both ears when an impulse is input to the virtual speaker 26 placed at point P. Also, xv, xH
is the impulse response of each convolver 22 and 23 (corresponding to the number of taps), bRr + hRQ + hLQ
, ) ILr + hl + h2 is length n, Xv is length ml,! It is assumed that H is a discrete sequence of length m2. Here, if an impulse is input to the input terminal 28,
Letting the response in both ears be PR9PL, it can be expressed as follows. However, the end indicates the convolution sum.

Further, if the response of both ears when an impulse is input to the speaker 2e is set as h+h, it can be expressed as follows.

In formula (1), xVH-! H*! V trunk). Then? ) can be rewritten as . Also, equation (4) can be written as and can be written as follows.

pl = Hx (6) Also, (3) xvH = xHxv
It can be rewritten as (9).

Here, considering that P' is approximated to P, the square of the difference between P' and P is set as the evaluation value d as shown in the following equation, and the tap coefficient X of the convolver that minimizes this d is determined. think about it.

d-(P'-P)t(P-P)'-(Hz-P(H
x-P)-xtHtHz-(x"H"P+P"H
x ) + PthP (10) If we partially differentiate the equation (1o) with respect to I and set it to 0, then -2H"Hx -2□t
, -8 ,8("9 From this, x = (H'H')H'P (1
2) By finding X from equation (12)! V is found, and from this, XH is found using equation (9).

Therefore, P can be approximated to P by setting the tap coefficient of each convolver 22, 23 to that value. Therefore, by determining the tap coefficients of the convolvers 22 and 23 using the algorithm described above and recording them in the memory 18, it is possible to localize the sound image at any position, and to independently position the sound image in the vertical and horizontal directions. can be controlled.

FIG. 4 shows the tap coefficients actually determined and expressed using the above algorithm. FIG. 4 shows the tap coefficients of the convolver 22 for vertical control when the sound image is localized to the upper and lower sides of the listener's median plane, respectively, and a is the lower 6
In the case of 0°, it is the case of bil1 phrase O. Also, the length of the impulse response of each speaker 24°26 is 6
The response length of the convolver 22 is calculated as 4 points (25 KHz sampling) and 32 points (25 KHz sampling). When localizing the sound image on the median plane, there is no need to find the XH tap coefficient of the horizontal control convolver 23, and the output signal of the vertical control convolver 22 may be input as is to both speakers 24 and 25. If you want to localize the electric image at all 24 points shown in Figure 2, then the tap coefficient of the convolver for the sound image in the horizontal plane, which includes both ears of the listener, and the upper and lower sides of the median plane for each sound image position. Position of sound image at 60° 12.1
By recording a total of 10 convolver tap coefficients for 3 in the memory 18, the sound image can be localized to all 24 points shown in Fig. 2, and the number of memories can be significantly reduced. O Fig. 5 shows another embodiment of the present invention, and in Fig. 6, 29.30 is an input terminal for left and right stereo signals;
1 is a reverberation signal generation circuit, 32 is a convolver for vertical direction control, 33 is a convolver for horizontal direction control, 34 and 35 are left and right speakers for reproduction, and 36 is a virtual speaker. Input terminal 29.30, l < ---, r --- After branching the acoustic signal input to the stamp into two and adding the other signal via the adder 38, the reverberation signal generation circuit '31 is inputted to the vertical control convolver 32 and the horizontal direction control convolver (and then added to one of the branched acoustic signals by the adders 39 and 40, in addition to left and right stereo playback. , the reverberant signal can be added from any position above or below the listener. FIG. 5 shows the case where the reverberant sound is added from above the median plane of the listener. may be set so that the sound image is localized above the median plane of the listener.Furthermore, the tap coefficient of the convolver 33 is set so that the input signal and output signal of the convolver 33 are equal.

Thereby, a sound image with reverberation added above the median plane can be localized at the position of the virtual speaker 36.

As described in detail below, according to the present invention, the acoustic signal is passed through the vertical control funvolution equalizer.
One of them is placed on the left and right sides of the listener, and the other is input to one speaker through a convolution equalizer for horizontal direction control, and the other is input to the other speaker. By changing the tap coefficient of the convolution equalizer for horizontal direction control, the sound image can be localized at any position above and below the listener's median plane and at any position in the horizontal direction of the listener. Further, it has the advantage that the amount of memory for storing the tap coefficients can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional sound image control device, FIG. 2 is a diagram showing the sound image position in the space around the listener, and FIG. 3 is a block diagram showing an embodiment of the sound image control device of the present invention. Figure 4 shows the tap coefficient of the convolver (impulse response of the convolver) when the sound image is localized 600 degrees above and below the listener.
FIG. 6 is a block diagram showing another embodiment of the sound image control device of the present invention. 18...Memory, 19...Decoder,
20°21...Joystick, 22...
...Convolution equalizer for vertical direction control,
23...Convolution equalizer for horizontal direction control, 24.25...Speaker, 31...
...Reverberation signal generation circuit. Name of agent: Patent attorney Toshio Nakao and one other person 2θ
2f Figure 4 (4+ - goods threshold

Claims (2)

[Claims] (1) A convolution equalizer for vertical direction control and a convolution equalizer for horizontal direction control configured to total the outputs from delay devices in which single delay elements are connected in cascade via a coefficient unit, and a listening device. Speakers placed on the left and right in front of the listener, transmission characteristics for localizing the sound image synthesized by these two speakers to any position above and below the median plane of the listener, and listening to the sound image synthesized by the above two speakers. A memory that stores the tap coefficients of the convolution equalizer for vertical direction control and the convolution equalizer for horizontal direction control corresponding to the transmission characteristics for localizing the user to any position in the horizontal direction; an operating means for specifying the position of the sound image, and a tap coefficient corresponding to the position of the specified sound image stored in the memory in response to the specification of the operating means, and reading out a tap coefficient corresponding to the position of the specified sound image, and the above-mentioned convolution equalizer for vertical direction control and the above-mentioned horizontal direction control. A decoder for controlling the convolution equalizer is not provided.The audio signal is input to the convolution equalizer for vertical direction control, the output of the convolution equalizer for vertical direction control is branched into two, and one signal is sent to the horizontal control convolution equalizer for vertical direction. A sound image control device configured to input a signal to one of the speakers through a convolution equalizer for direction control, and input the other signal directly to the other speaker. (2) The sound image control device according to claim 1, wherein the acoustic signal is a signal obtained by adding left and right stereo signals and passing the resulting signal through a reverberation generation circuit.