JP3067140B2 - 3D sound reproduction method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a stereophonic sound reproducing method.

(Summary of the Invention) The present invention relates to a stereophonic sound reproducing method, in which a plurality of loudspeakers each having a variable delay element and a variable volume adjuster and a reflector are used to form a focal point of a sound wave in a sound field. Has a stereo sound field as a new lower layer sound source.

This facilitates control of the sense of distance of the sound image, which has been difficult in the past.

(Prior Art) Conventional stereophonic sound reproduction methods include the following methods.

The first conventional example is called stereophonic (two-channel stereo), which is a method in which two systems of sounds are reproduced and heard in a sound field using two speakers. This is a method called binaural (dummy head recording), in which two left and right sounds collected using a dummy head are reproduced using headphones. The third conventional example is quadraphonic (channel stereo). This is a method of reproducing four systems of sounds using four or more speakers.

In addition, although not as common as the above three methods, there are also a three-channel stereo method and a method with more channels.

(Problems to be Solved by the Invention) The conventional method has the following disadvantages.

First, it is difficult to control the sense of distance to the sound image, particularly to present (perceive) the sound image in front of the speaker.

When the sound source is close, the distance to the sound image can be relatively correctly estimated. The reason is that the diffraction state of the sound wave by the listener's head changes greatly depending on the sound source distance,
It is said that it adds to the clues to make subtle differences in the difference between the ears. Therefore, it is considered that even in a conventional stereo, if the sound pressure at the entrance of both ears of the listener is precisely controlled, the sense of distance of the sound image can be controlled. However, in this method, since the amount of control depends on the geometrical structure of the head and ears of each listener, control for each listener is required, and this method cannot be practical.

The second drawback is that it is difficult to perform stable sound image localization that does not depend on the listener's head movement.

In the conventional stereophonic sound reproduction method, since the change in sound pressure generated in both ears when the listener moves the head is different from that in the original sound field, there is an unnaturalness that the sound image direction depends on the head direction. . This can be said regardless of speaker reproduction and headphone reproduction.

Therefore, an object of the present invention is to achieve the above-described "control of sense of distance of sound image" and "localization of sound image independent of the direction of the listener's head", which are difficult with the conventional method. It is intended to provide a three-dimensional sound reproduction method.

(Means for Solving the Problems) That is, in order to achieve this object, the stereophonic sound reproducing method according to the present invention provides a plurality of speakers each having a variable delay element and a variable volume controller on the same curved surface or It is arranged on the same plane, supplies the same audio signal to the plurality of speakers, and adjusts one or both of the delay amount of each of the variable delay elements and the volume of each of the variable volume controllers in each speaker. Then, one or more focal points of the sound waves emitted by the plurality of speakers are formed between the listener and the speakers, and the focal points can be used as a new virtual sound source to expand the control of the sense of distance of the sound image. It is characterized by constituting a field.

(Operation) According to the method of the present invention, instead of controlling the sound pressures at the entrances of both ears of a conventional listener to create a three-dimensional effect, a virtual sound source is newly created, and the sound source is thereby newly generated. Since the spherical wave centered at the center is formed, the sound field itself is partially reproduced, so that even if the listener moves his or her head slightly, a stable sound image localization can be obtained, and a natural feeling can be obtained. A certain three-dimensional sound reproduction feeling can be obtained, and the listening position can be expanded.

(Example) Hereinafter, the method of the present invention will be described in detail with reference to the accompanying drawings by way of examples.

First, FIG. 1 shows a first embodiment according to the method of the present invention. In this case, this is a speaker reproducing apparatus that supplies the same signal 2 to a large number of speaker groups 1 arranged in a spherical shape and drives them. At the center 3 of the spherical surface of this device, the phases of the sound waves from the respective speakers of the speaker group 1 coincide with each other, and a place having a very high sound pressure, such as a focal point in light, is created. Thus, a spherical wavefront centered on the center 3 of the spherical surface is positioned on the opposite side 4 of the speaker.
Formed. When the listener places his or her head in this, a diffraction effect similar to that when a real sound source is placed at the center 3 of the spherical surface occurs, so that the sound also seems to be heard from the center 3 in terms of hearing. That is, a virtual sound source is generated at the center 3 of the spherical surface. The wavefront of the virtual sound source is different from the synthetic wavefront of the stereo, and has a similar structure to the wavefront of the real sound source. Therefore, the direction of the sound image does not change even if the listener slightly moves the head.

If variable delay elements are used for these speakers, it is not necessary to arrange the speakers in a spherical shape. FIG. 2 shows a second embodiment using a variable delay element. This embodiment includes a speaker group 5 arranged on a plane, a delay element group 6 connected to each speaker, and a control unit 7 for controlling a delay amount. In this embodiment, the delay amount is adjusted so that the phases of the sound waves from the respective speakers become equal at a desired position 8 in the sound field. In this way, the sound pressure at position 8 is increased and a spherical wavefront is formed therefrom. By combining a plurality of the second embodiments, a plurality of virtual sound sources can be created. In the second embodiment, the delay element is included on the reproduction side, but may be included on the sound collection side.

In the first embodiment, a variable delay element is provided for each speaker.
A variable sound volume adjuster is attached, and these are controlled by the control unit, and the delay amount and volume of each speaker can be controlled to create a plurality of sound wave focal points, and the focal points can be moved, that is, move. It is also possible to create multiple sound images.

FIG. 3 shows a third embodiment of the present invention in which the sense of distance of a sound image can be controlled without using a delay element. This embodiment is a speaker reproducing apparatus for supplying the same signal 10 via a volume controller 11 to speakers 15 to 23 arranged on a spherical surface as in the first embodiment. If the magnitudes of the signals supplied to the speakers are equal, the conditions are exactly the same as in the first embodiment, and
A virtual sound source is generated, and a sound image is perceived at that location. However, here, when signals are supplied only to the speakers 17, 18, 19, 20, and 21, the width of the sound source becomes narrower than the condition for driving all the speakers, and is formed at the center 14 of the spherical surface. The focal point of the sound wave becomes somewhat imperfect. The center of the wavefront formed on the opposite side of the focal point is also slightly away from the speaker,
It is around 13 between 19 and the center 14 of the spherical surface. Next, the speaker
When a signal is supplied only to the speaker 19, a sound image is naturally perceived at the location of the speaker 19. Thus, by controlling the number of speakers to be driven without using a delay element, it is possible to control the sense of distance between sound images.

Although the three embodiments have been described above, the present invention is not limited thereto, and various modifications and changes can be made without departing from the gist of the present invention.

(Effects of the Invention) The effects obtained by the method of the present invention are as follows.

First, a sound image can be presented before the speaker. In the conventional method, since only the sound pressure at the entrances of both ears is controlled, the effect disappears when the listener's head is moved, and the method is unstable. According to the present invention, since a spherical wave centered on the virtual sound source is formed, the listener may slightly move his / her head, and stable localization can be obtained.

For the same reason as the first advantage, the second advantage can present a sound image that does not move even if the listener moves his / her head.

A third advantage is that the thickness of the reproducing apparatus can be reduced. In the conventional reproducing method, one sound image is composed of two speaker outputs. Therefore, in order to achieve high sound quality, it is necessary to widen the band of the speaker itself, and it is inevitable that the apparatus becomes large. According to the method of the present invention, the area of responsibility of one speaker can be reduced, so that the size of the speaker alone can be small. Therefore, the device can be made thinner.

[Brief description of the drawings]

1, 2 and 3 show first, second and third embodiments according to the method of the present invention, respectively. DESCRIPTION OF SYMBOLS 1 ... Speaker group 2 ... Input signal 3 ... Center of spherical surface 4 ... Area | region where spherical wave is formed 5 ... Speaker group, 6 ... Variable delay element group 7 ... Delay amount control part, 8 ... … One point in the sound field 9… input signal, 10… input signal 11… volume controller 12… gain control signal 13… midpoint of the center of the sphere of the speaker 19 14… center of the sphere, 15 to 23 …… Speaker

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Koichi Kurozumi 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Japan Broadcasting Corporation Broadcasting Research Institute (56) References JP-A-62-21400 (JP, A) 51-113424 (JP, U) Jikken 46-17171 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04S 1/00 H04R 1/40 310

Claims (1)

(57) [Claims] A plurality of speakers each having a variable delay element and a variable volume controller are arranged on the same curved surface or on the same plane, and the same audio signal is supplied to the plurality of speakers. By adjusting one or both of the delay amount of each of the variable delay elements and the volume of each of the variable volume controllers, one of the focal points of the sound waves emitted from the plurality of speakers is set between the listener and the speaker. Alternatively, a stereophonic sound reproduction method characterized in that a plurality of points are formed, the focus of which is used as a new virtual sound source, control of the sense of distance of a sound image can be expanded, and a stereo sound field is formed.