JPH11239400A - Speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a system small in size, to increase a suppression rate of a sound from other sound sources and to obtain a suppression effect over a wide range in the speaker system where two listeners in the same space can listen to the sound of different sound sources. SOLUTION: In this speaker system using signals from two sound sources, a sound wave to cancel a sound wave outputted from a woofer 6a and a tweeter 7a is outputted from a woofer 6b and a tweeter 7b by using digital filters and delay devices or the like so as to allow a listener to listen to only the sound from the woofer 6b and the tweeter 7b in an area in front of the woofer 6b and the tweeter 7b by canceling crosstalk from the woofer 6a and the tweeter 7a. Then the interval between the woofers 6a and 6b and the interval between the tweeters 7a, 7b is selected to be one wavelength or below and 1/8 wavelength or over (40 cm, 5 cm) respectively with respect to the frequency of the controlled sound wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device suitable for use in enabling two (or two groups) listeners in the same space to simultaneously listen to sounds from different sound sources.

[0002]

2. Description of the Related Art Conventionally, a device for simultaneously listening different sounds in different areas of the same space has, for example, controlled the directivity of sound radiated from a speaker in two or more desired directions. There was something like that. JP 6
In the device described in JP-A-205496 "Speaker device", a desired directivity is obtained by using an array speaker in which a plurality of speakers are linearly arranged and individually performing digital signal processing on signals supplied to each speaker. I was trying to make it happen. In the device described in this publication, signal processing for varying the delay time and the like is performed on a plurality of signals supplied to each speaker by digital filters connected to each speaker, thereby releasing the signal. The directivity of the sound being sounded was controlled.

[0003] An example of a technique for giving the directivity of a speaker in an arbitrary direction structurally is disclosed in Japanese Patent Laid-Open No. 5-34.
No. 4579, "Speaker system and a television receiver using the speaker system". In the speaker device described in this publication, 2
Using two horn speakers, optimize the shape of the acoustic tube that guides the sound waves radiated from the speaker diaphragm and the arrangement of the partition plate and sound absorbing material used in combination with the acoustic tube in the direction of the direction, directing in any direction I was trying to get sex.

Japanese Patent Laid-Open Publication No. Hei 5-333778 discloses a "crosstalk sound control device" which, unlike the above, synthesizes a canceling sound by digital signal processing when different sounds are emitted from two adjacent speakers. This describes a technique that reduces crosstalk sound and allows only a desired sound to be heard from a plurality of sounds in different regions of the same space. In the device described in this publication, attention is paid to the fact that the change in the transfer function from the speaker built into the chair of a train, an aircraft, or the like to the person sitting thereon corresponds to the angle of the back of the chair, and the angle is detected. This makes it possible to omit the microphone that has been conventionally used for error detection in a device that generally synthesizes a canceling sound by digital signal processing.

[0005]

By the way, in the above-mentioned conventional speaker device, for example, in the case where an array speaker including a plurality of speakers is subjected to digital signal processing, a plurality of speakers and a digital filter are used. However, there is a problem that the apparatus becomes large-scale. On the other hand, the combination of the horn speaker and the acoustic partition plate has a problem that the intended effect, that is, the suppression ratio of sound radiated toward another region in a certain region is small.

On the other hand, as described in JP-A-5-333878, a canceling sound is synthesized by digital signal processing using a speaker with a built-in chair and a sensor for detecting the backrest angle of the chair. Then
There is a problem that the area (volume) to cancel out is narrow. In addition, in order to perform signal processing, an angle sensor for detecting the angle of the backrest of the chair was required,

The present invention has been made in view of such a background, and solves the above-mentioned problem, whereby two (or two groups) listeners in the same space can hear sounds from different sound sources. It is an object of the present invention to provide a speaker device that can be configured as described above. It is an object of the present invention, in particular, to reduce the size of the device, increase the suppression ratio of undesired sound sources or undesired sound sources, and obtain effects over a wide area.

[0008]

To solve the above-mentioned problems, the invention according to claim 1 comprises a first speaker and a second speaker.
And a control unit that causes the first speaker to emit a sound wave that cancels out sound waves emitted from the second speaker due to interference between the sound waves, wherein the first and second speakers are used. Are arranged at intervals of not more than one wavelength and not less than ８ wavelength in the frequency range of the sound wave to be controlled. Further, the invention according to claim 2 further includes a third speaker and a fourth speaker, wherein the control means includes:
Further, the sound wave radiated from the fourth speaker is
A sound wave to be canceled by interference between sound waves is emitted from the third speaker, and at this time, by the control means,
The frequency range of the sound wave controlled using the first and second speakers and the frequency range of the sound wave controlled using the third and fourth speakers are different from each other, and the first and second sound waves are controlled. The arrangement intervals of the speakers and the arrangement intervals of the third and fourth speakers are different from each other so as to be equal to or less than one wavelength and equal to or more than ８ wavelength of the frequency range of the sound wave to be controlled. It is characterized by:

According to the above configuration, for example, even when two-way stereo speakers including, for example, third and fourth speakers for high frequencies are used in addition to the first and second speakers for low frequencies, the other speakers are used. Can cancel each other out by using the sound wave interference.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of one embodiment of a speaker device according to the present invention. The speaker device 100 shown in FIG.
a, 1b, and a signal output from each of the sound sources 1a, 1b is processed by each internal block, and then emitted as sound waves from the bass speakers 6a, 6b and the treble sound speakers 7a, 7b. Have been.

The signal output from the sound source 1a is
a and the signal output to the digital filter 3b and output from the sound source 1b are input to the delay unit 2b and the digital filter 3a. The signal input from the sound source 1a to the delay unit 2a is delayed by a time substantially equal to the signal processing time in the digital filter 3a, and then added to the adder 4a.
, Where it is added to the signal output from the digital filter 3a. Similarly, the signal input from the sound source 1b to the delay unit 2b is delayed by a time substantially equal to the signal processing time in the digital filter 3b, and then input to the adder 4b, where the signal output from the digital filter 3b is converted into a signal. Is added.

Output signals of the adders 4a and 4b are amplified by amplifiers 5a and 5b, respectively. The signal output from the amplifier 5a is connected to the crossover network 8a.
Are distributed according to the frequency, input to the low-pitched speaker 6a and the high-pitched speaker 7a, and radiated into the space as sound waves. The signal output from the amplifier 5b is distributed according to the frequency in the crossover network 8b, input to the bass speaker 6b and the treble speaker 7b, and radiated as sound waves into the same space as above.

In the above configuration, the low-pitched speaker 6a and the high-pitched speaker 7a are used for the sound heard in the space.
The following describes an example of the space area a in front of the above. The sound heard in the area a is obtained by linearly superimposing the sounds radiated from the speakers 6a, 6b, 7a, 7b. The microphone output voltage when the microphone is placed at one point of the area a is A (ω), the output voltage of the sound source 1a is X (ω), and the output voltage of the sound source 1b is Y
(Ω is the (angular) frequency), the microphone output voltage A placed in the area a is

A = (αX + βY) + (γX + δY)

## EQU1 ## Here, α is sound source 1a →
The transfer function is a delay device 2a → adder 4a → amplifier 5a → crossover network 8a → bass speaker 6a and treble speaker 7a and a space. β
Is sound source 1b → digital filter 3a → adder 4a →
The transfer function has a path through the amplifier 5a → the crossover network 8a → the bass speaker 6a and the treble speaker 7a, and the space. γ is a transfer function that takes the sound source 1a → the digital filter 3b → the adder 4b → the amplifier 5b → the crossover network 8b → the bass speaker 6b and the treble speaker 7b and the space as a route.
δ is sound source 1b → delay 2b → adder 4b → amplifier 5b →
Crossover network 8b → bass speaker 6
b, the treble speaker 7b, and a transfer function with space as a path.

That is, the first term on the right side in parentheses is the sound radiated from the speakers 6a and 7a and heard in the area a, and the second term on the right side in brackets is the speakers 6b and 7
The sound radiated from b and heard in the area a is shown.
By adjusting the digital filter 3a to change β, β =
When −δ is satisfied, the above equation is A = αX + γX = (α + γ)
It becomes X and the term containing Y is deleted. This means that only the sound from the sound source 1a is heard in the region a, and the sound from the sound source 1b (crosstalk; the sound from the sound source 1a in the region b) is not heard. By performing the same operation on the digital filter 3b, the sound from the sound source 1a cannot be heard in the region b.

In order to obtain the transfer function as described above, the coefficients of the digital filters 3a and 3b are calculated, for example, from the results of experiments or simulations using a space in which the speaker device 100 is actually used or a space similar to that used. It is adjusted in advance based on this. Each coefficient set in the digital filters 3a and 3b is stored in a memory or the like in the speaker device 100. The digital filters 3a and 3b include well-known FIR (finite impulse response) filters and IIR (infinite impulse response).
It can be constituted by a filter or the like.

With such a configuration, the digital filter ensures that β = −δ is satisfied at only one point in the area a, and the crosstalk becomes zero at that point. Then, a space with a small amount of crosstalk is generated around it. In general, if speakers are installed sufficiently far apart in a diffuse sound field,
It is said that the space below 10 dB is about one tenth of the wavelength of the sound wave of the control zone (A. David and SJElli).
ot 1993 applied acoustics 41,63-79.Numerical studi
es of actively generated quiete zones).

Conversely, when the sound sources are brought closer to one-eighth or less of the wavelength of the sound wave of the control frequency, the crosstalk becomes negative.
The space of 10 dB or less extends in front of both speakers, and in the case of a two-channel configuration, the crosstalk reduction areas overlap. FIG. 2 shows that the distance between the two speakers is changed from d ₁ to d ₃ and the wavelength of the sound is λ.
FIG. 9 is a schematic diagram showing how a region where the crosstalk is −10 dB or less changes when “1” is set. FIG.
(A) shows the distance d ₁ between the two speakers 60a and 60b.
Is greater than the center wavelength λ of the sound wave radiating the
a to intensity of sound wave (for example, output voltage of microphone)
Region 70a-1 having a size of -10 dB or less with respect to
And a region 70b-1 in which the crosstalk from the speaker 60a has a magnitude of -10 dB or less with respect to the sound wave from the speaker 60b. FIG. 2 (B), a speaker 60a, following the spacing d ₂ wavelength λ of 60b, areas 70a-2 that crosstalk from the speaker 60b in the case of the above-eighth 1λ is the following size -10dB
And the crosstalk from the speaker 60a is -10 dB
An area 70b-2 having the following size is shown. FIG. 2C shows a region 70a-3 in which the crosstalk from the speaker 60b is −10 dB or less when the distance d ₃ between the speakers 60a and 60b is less than 1 / 8λ; In the region 70b-3 where the crosstalk is less than or equal to −10 dB.

In the loudspeaker apparatus of the present invention, attention is paid to the above points, and by setting the interval between the two loudspeakers at one wavelength or less and １ ／ wavelength or more, an independent large volume crosstalk reduction region is generated. ing. In a configuration using one set of low-pitched speaker and high-pitched speaker as in the speaker apparatus whose block configuration is shown in FIG. 1, both the low-pitched speaker and the high-pitched speaker having different wavelengths satisfy the above conditions. By arranging them at different intervals as described above, it is possible to obtain good crosstalk reduction characteristics even in a wide frequency band.

FIG. 3 shows the speaker device 10 shown in FIG.
FIG. 9 is a diagram illustrating an example of the appearance of the “0”. In the speaker device 100 shown in FIG. 3, each speaker 6a, 6b, 7a, 7b
Are linearly arranged on the front of the same speaker box, and bass speakers 6a,
The distance between the centers of 6b is 40 cm, and the distance between the centers of the high frequency speakers 7a and 7b is 5 cm. When the speakers are arranged in this manner, two of the inner high-frequency speakers 7a and 7b are 850-6800H.
Good directivity is obtained in the band z, and the two outer bass speakers 6a and 6b have good directivity in the band of 106 to 850 Hz. Therefore, in this case, 110 to 68
Crosstalk reduction in a desired area can be obtained in a wide band of 00 Hz.

As described above, in the present embodiment, when the crosstalk is reduced by the speaker device using the digital filter, the speakers corresponding to each area are constituted by two speakers for each of the bass and treble. Since the installation intervals for the bass and treble are set to be less than 1 wavelength and more than 1/8 wavelength of the frequency range of the sound wave to be controlled, respectively, compared to the case where the directivity is controlled using an array speaker, The device can be downsized.
Further, by dividing the frequency region to be controlled into a plurality of regions and providing a dedicated speaker for each frequency region, it is possible to obtain a good crosstalk suppression ratio in a wide frequency region. For example, in a speaker device in which four speakers are arranged as shown in FIG. 3, it has been confirmed that a crosstalk suppression ratio of 15 dB or more can be obtained in a wide area of 0.5 m to 1 m square.

In the speaker device of the present invention, a practically sufficient crosstalk suppression ratio can be obtained by setting the speaker arrangement interval to the above-described condition. Therefore, basically, a sensor such as a microphone is combined. In addition, it is not necessary to use a configuration in which the coefficient of the digital filter is feedback-controlled. Therefore, the configuration can be simplified.

In the above-described embodiment, crosstalk is reduced by preparing digital filter coefficients in advance without using a sensor such as a microphone. Can be configured by a well-known adaptive filter or the like. Further, the configuration of the speaker is not limited to the configuration in which one set of speakers is provided for each of the bass and treble as shown in FIGS.
By changing the configuration of the crossover networks 8a and 8b, only one set of speakers or three or more sets of speakers can be used.

The speaker device of the present invention may be used, for example, as a speaker of a television audio multiplex broadcast receiver to provide a main audio / video multiplex broadcast television receiver.
It is possible that two people (or two groups) can enjoy the sub-channel simultaneously with different sounds. Also,
As another application example, it can be used as a speaker device for a PA device that performs different broadcasts in two areas in a station yard or the like.

[0026]

As described above, according to the present invention, a speaker device having control means for causing a sound wave emitted from a second speaker to be canceled by interference between sound waves from a first speaker. In the above, the first and second speakers are arranged at intervals of one wavelength or less and one eighth or more wavelengths in the frequency range of the sound wave to be controlled. A speaker device that enables a listener (or two groups) to hear sounds from different sound sources, in which the size of the device is reduced, the suppression ratio with respect to the sounds of other sound sources is improved, and the effect in a wide area is achieved. Acquisition can be possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a speaker device according to the present invention.

FIG. 2 shows the speaker spacing as d ₁ (FIG. 2 (A)), d
₂ (FIG. 2 (B)) and d ₃ (FIG. 2 (C)) are hatchings showing regions where crosstalk is −10 dB when a sound wavelength is λ.

FIG. 3 is an external view of the speaker device shown in FIG. 1 in which each speaker is arranged in one speaker box in two ways.

[Explanation of symbols]

1a, 1b ... sound source, 2a, 2b ... delay unit, 3a, 3b ...
Digital filters, 4a, 4b ... adders, 5a, 5
b: amplifier, 6a, 6b: bass speaker, 7a, 7
b: treble speaker, 8a, 8b: crossover network.

Claims (2)

[Claims] A first speaker; a second speaker; and control means for causing the first speaker to emit a sound wave that cancels out a sound wave emitted from the second speaker due to interference between the sound waves. Speaker device, wherein the first and second speakers are arranged at an interval of one wavelength or less and one-eighth wavelength or more of a frequency range of a controlled sound wave. 2. The apparatus further comprising: a third speaker and a fourth speaker, wherein the control unit further includes a third speaker for canceling a sound wave radiated from the fourth speaker due to interference between the sound waves. Of the sound wave controlled by the control means using the first and second speakers, and the sound wave frequency controlled by the third and fourth speakers. A frequency domain different from each other, and an arrangement interval between the first and second speakers and the third
2. The arrangement interval between the first speaker and the fourth speaker is different from each other so as to be equal to or less than one wavelength and equal to or more than one eighth wavelength of the frequency range of the sound wave to be controlled. Speaker device.