JP3422247B2 - Speaker device - Google Patents

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 allowing two (or two groups) listeners in the same space to hear sounds of different sound sources at the same time.

[0002]

2. Description of the Related Art Conventionally, in a device for simultaneously listening to different sounds in different regions of the same space, for example, the directivity of sounds emitted from a speaker is controlled in two or more desired directions. There was something I did. JP-A-6
In the device described in Japanese Unexamined Patent Publication No. 205496, "Speaker Device", an array speaker in which a plurality of speakers are linearly arranged is used, and a signal to be supplied to each speaker is individually subjected to digital signal processing to obtain a desired directivity. I was trying to make it happen. In the device described in this publication, signal processing is performed on a plurality of signals supplied to each speaker by a digital filter respectively connected to each speaker so that the delay time and the like are made different, and thereby the signals are emitted. The directivity of the sound being played was controlled.

An example of a technique for structurally giving a speaker directivity in an arbitrary direction is disclosed in Japanese Patent Laid-Open No. 5-34.
No. 4579, "Speaker System and Television Receiver Using the Speaker System". In the speaker device described in this publication, 2
By using two horn speakers, the shape of the acoustic tube that guides the sound waves emitted from the speaker diaphragm and the layout of the partition plate and the sound absorbing material used in combination with the acoustic tube are optimized in the directional direction, and the direction of any direction I was trying to get sex.

Further, in Japanese Patent Application Laid-Open No. 5-333878, "Crosstalk sound control device", unlike the above, when a different sound is emitted from two adjacent speakers, a canceling sound by digital signal processing is synthesized. Thus, a technique is disclosed in which crosstalk sound is reduced and only a desired sound can 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 airplane, etc. to the sitting person depends on the angle of the backrest of the chair, and the angle is detected. This makes it possible to omit the microphone that has been 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 was a problem that the device became large-scale. On the other hand, the combination of the horn speaker and the acoustic partition plate has a problem that the desired effect, that is, the suppression ratio of the sound radiated to another area in one area is small.

On the other hand, 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, as described in JP-A-5-333878. Then
There is a problem that the area (volume) to be canceled is small. Also, in order to perform signal processing, an angle sensor for detecting the angle of the backrest of the chair was necessary,

The present invention has been made under such a background, solves the above-mentioned problem, and allows two (or two) listeners in the same space to hear sounds of different sound sources. It is an object of the present invention to provide a speaker device capable of performing the above. An object of the present invention is, in particular, to downsize the device, increase the suppression ratio for sounds of undesired sound sources and sounds of sounds that one does not want to hear, and obtain an effect in a wide range.

[0008]

In order to solve the above problems, the invention according to claim 1 provides a first speaker and a second speaker.
Speaker device and control means for causing a sound wave emitted from the second speaker to be canceled by interference between the sound waves from the first speaker, the speaker device comprising: The speakers are arranged at intervals of not more than 1 wavelength and not less than 1/8 wavelength of the frequency range of the controlled sound wave. Further, the invention according to claim 2 further comprises a third speaker and a fourth speaker, and the control means comprises:
Furthermore, the sound wave emitted from the fourth speaker is
A sound wave that is canceled by the interference between the sound waves is emitted from the third speaker, and at that time, by the control means,
The frequency range of the sound waves controlled using the first and second speakers and the frequency range of the sound waves controlled using the third and fourth speakers are different from each other, and The arrangement intervals of the speakers and the arrangement intervals of the third and fourth speakers are different from each other so that the intervals are not more than 1 wavelength and not less than 1/8 wavelength of the frequency region of the controlled sound wave. It is characterized by that.

According to the above configuration, even when a two-way stereo speaker including, for example, the first and second speakers for low frequencies and the third and fourth speakers for high frequencies is used, the other Sounds emitted from the speakers can be canceled each other by using sound wave interference.

[0010]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a speaker device according to the present invention. The speaker device 100 shown in FIG. 1 has two sound sources 1.
a, 1b, and the signal output from each sound source 1a, 1b is processed by each internal block, and then radiated as a sound wave from the bass speaker 6a, 6b and the treble speaker 7a, 7b. Has been done.

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

The output signals of the adders 4a and 4b are amplified by amplifiers 5a and 5b, respectively. Then, the signal output from the amplifier 5a is the crossover network 8a.
At, the sound is distributed according to the frequency, is input to the bass speaker 6a and the treble speaker 7a, and is radiated into the space as a sound wave. Further, the signal output from the amplifier 5b is distributed in the crossover network 8b according to the frequency, is input to the bass speaker 6b and the treble speaker 7b, and is radiated to the same space as the sound wave.

In the above structure, the bass speaker 6a and the treble speaker 7a for the sound heard in the space.
An example will be described of the space region a in front of the. The sound heard in area a is a linear superposition of the sounds emitted from the speakers 6a, 6b, 7a, 7b. The microphone output voltage when the microphone is placed at one point in 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.
Assuming that (ω) (ω is (angular) frequency), the microphone output voltage A placed in the area a is

A = (α X + β Y) + (γ X + δY)

It is expressed as follows. Where α is the sound source 1a →
The transfer function has a delay path 2a, an adder 4a, an amplifier 5a, a crossover network 8a, a bass speaker 6a and a treble speaker 7a, and a space. β
Is sound source 1b → digital filter 3a → adder 4a →
The amplifier 5a → crossover network 8a → low-range speaker 6a and high-range speaker 7a, and a transfer function having a space as a path. γ is a transfer function having a path in 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.
δ is the sound source 1b → the delay device 2b → the adder 4b → the amplifier 5b →
Crossover network 8b → bass speaker 6
b and the high-pitched speaker 7b, and a transfer function having a space as a path.

That is, the first term on the right side enclosed in brackets is the sound radiated from the speakers 6a, 7a and heard in the region a, and the second term on the right side enclosed in brackets is the speakers 6b, 7a.
The sound radiated from b and heard in the area a is shown.
Adjust the digital filter 3a to change β and β =
If −δ is satisfied, the above formula becomes A = αX + γX = (α + γ)
It becomes X, and the term including Y is deleted. This means that only the sound from the sound source 1a is heard in the area a, and the sound from the sound source 1b (crosstalk; the sound from the sound source 1a in the area b) cannot be heard. By performing the same operation on the digital filter 3b, the sound originating 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 determined by, for example, an experiment or simulation result using a space in which the speaker device 100 is actually used or a space similar to that used. Based on this, it is adjusted in advance. The coefficients set in the digital filters 3a and 3b are stored in a memory or the like in the speaker device 100. The digital filters 3a and 3b are well-known FIR (finite impulse response) filters and IIR (infinite impulse response).
It can be configured by a filter or the like.

In such a configuration, the digital filter guarantees the establishment of β = −δ at only one point in the area a, and the crosstalk becomes zero at that one point. Then, a space corresponding to that with less crosstalk is generated around it. Generally speaking, when speakers are installed far enough apart in a diffuse sound field, crosstalk-
The space below 10 dB is said to be about one tenth of the wavelength of the sound waves of the control belt (A.David and SJElli
ot 1993 applied acoustics 41,63-79.Numerical studi
es of actively generated quiete zones).

On the contrary, when the sound sources are brought closer to ⅛ or less of the wavelength of the sound wave of the control frequency, the crosstalk is −
The space of 10 dB or less spreads in front of both the two speakers, and in the case of the two-channel configuration, the crosstalk reduction regions overlap each other. In FIG. 2, the wavelength of the sound is changed by λ by changing the distance between the two speakers from d ₁ to d _3.
FIG. 6 is a schematic diagram showing how the region where the crosstalk becomes −10 dB or less changes when. Figure 2
(A) shows the distance d ₁ between the two speakers 60a and 60b.
When the center wavelength λ of the sound wave radiated by
Sound intensity from a (eg microphone output voltage)
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.
A region 70b-2 having the following size is shown. Then, FIG. 2 (C), a speaker 60a, a region 70a-3 which crosstalk is equal to or less than a size -10dB from the speaker 60b when the 60b spacing d ₃ of is less than 8 minutes 1 [lambda, from the speaker 60a Area 70b-3 in which the crosstalk is about −10 dB or less.

In the speaker device of the present invention, paying attention to the above points, it is possible to generate an independent large volume crosstalk reduction region by disposing the interval between the two speakers at 1 wavelength or less and 1/8 wavelength or more. ing. Further, in a configuration using a pair of low-pitched speaker and high-pitched speaker as in the speaker device having the block configuration shown in FIG. 1, both low-pitched loudspeakers and high-pitched loudspeakers having different wavelengths satisfy the above condition. By arranging them at different intervals, good crosstalk reducing characteristics can be obtained even in a wide frequency castle.

FIG. 3 shows the speaker device 10 shown in FIG.
It is a figure which shows an example of the external appearance of 0. In the speaker device 100 shown in FIG. 3, each speaker 6a, 6b, 7a, 7b
Are arranged in a straight line on the front surface of the same speaker box, and at the same time, the bass speaker 6a is arranged outside.
The distance between the centers of 6b is 40 cm, and the distance between the centers of the high-pitched loudspeakers 7a and 7b arranged inside is 5 cm. If each speaker is arranged in this way, the two inside high-pitched speakers 7a and 7b are 850-6800H.
The z direction has good directivity, and the two outside bass speakers 6a and 6b have good directivity in the 106 to 850 Hz band. 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 crosstalk is reduced by the speaker device using the digital filter, the speaker corresponding to each area is composed of two speakers for bass and two speakers for treble. Since the installation intervals for the low-pitched sound and the high-pitched sound are each set to 1 wavelength or less and 1/8 wavelength or more of the frequency range of the sound wave to be controlled, compared with the case where the directivity is controlled using the array speaker, The device can be downsized.
Further, by dividing the frequency region to be controlled into a plurality of parts and providing a dedicated speaker for each frequency region, it becomes possible to obtain a good crosstalk suppression ratio in a wide frequency region. For example, it has been confirmed that the speaker device in which four speakers are arranged as shown in FIG. 3 has a crosstalk suppression ratio of 15 dB or more in a wide area of 0.5 m to 1 m square.

In the speaker device of the present invention, it is possible to obtain a crosstalk suppression ratio that is practically sufficient by setting the speaker arrangement intervals to the above conditions. Therefore, basically, a sensor such as a microphone is combined. , It is not necessary to use a configuration such as feedback controlling the coefficient of the digital filter. Therefore, the structure can be simplified.

In the above-described embodiment, the crosstalk is reduced by preparing the coefficient of the digital filter in advance without using the sensor such as the microphone, but the microphone is used and the digital filter is used. Can be configured by a well-known adaptive filter or the like. In addition, the configuration of the speaker is not limited to the one in which one set of speaker is provided for bass and the other set of speaker for treble as shown in FIG. 1 and FIG.
By changing the configuration of the crossover networks 8a and 8b, it is possible to use only one set of speakers or use three or more sets of speakers.

The speaker device of the present invention can be used, for example, as a speaker of a receiver of a television sound multiplex broadcast, so that it can be used as a main speaker of a television sound multiplex broadcast.
It is possible to allow the sub-channel to be enjoyed by two people (or two groups) at the same time with different sounds. Also,
As another application example, it can be used as a speaker device for a PA device that broadcasts differently to two areas in a station yard or the like.

[0026]

As described above, according to the present invention, the speaker device including the control means for causing the first speaker to emit the sound wave that cancels the sound wave emitted from the second speaker by the interference between the sound waves. In the above, since the first and second speakers are arranged at intervals of not more than 1 wavelength and not less than 1/8 wavelength of the frequency range of the controlled sound wave, two people in the same space can be compared to the conventional one. In a speaker device capable of allowing listeners (or two groups) to hear sounds of different sound sources, downsizing of the device, improvement of suppression ratio to sounds of other sound sources, and effect in wide range Can be earned.

[Brief description of drawings]

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

[Fig. 2] Speaker spacing is d ₁ (Fig. 2 (A)), d
₂ (FIG. 2 (B)) and d ₃ (FIG. 2 (C)) are schematic diagrams in which the regions where the crosstalk is −10 dB are hatched when the wavelength of sound is λ.

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

[Explanation of symbols]

1a, 1b ... Sound source, 2a, 2b ... Delay device, 3a, 3b ...
Digital filter, 4a, 4b ... Adder, 5a, 5
b ... amplifier, 6a, 6b ... bass speaker, 7a, 7
b ... treble speaker, 8a, 8b ... crossover network.

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Claims (2)

(57) [Claims] 1. A first speaker, a second speaker, and control means for causing a sound wave emitted from the second speaker to be emitted from the first speaker so as to cancel the sound wave by interference between the sound waves. A speaker device, wherein the first and second speakers are arranged at intervals of 1 wavelength or less and ⅛ wavelength or more of a frequency region of a controlled sound wave. 2. A third speaker and a fourth speaker are further provided, and the control means further applies a sound wave that cancels a sound wave emitted from the fourth speaker due to interference between the sound waves to each other. Of the sound waves controlled by the control means using the first and second speakers and the sound waves controlled by the third and fourth speakers by the control means. The frequency range is different from each other, and the arrangement interval of the first and second speakers is different from that of the third speaker.
2. The arrangement intervals of the fourth speaker and the fourth speaker are different from each other such that the intervals are not more than 1 wavelength and not less than 1/8 wavelength of the frequency region of the controlled sound wave. Speaker device.