JPH06311582A - Speaker device - Google Patents

Abstract

PURPOSE:To obtain a speaker device with low interference between the reproducing tone of a full-range speaker and that of a woofer and with satisfactory normal position for an image and capable of increasing distance between both speakers. CONSTITUTION:Closed type full-range speakers 16L, 16R and closed type woofers 26L, 26R are arranged by spatially separating. A signal from an audio signal source 11 is supplied to the full-range speakers 16L, 16R. The high frequency tone range of the signal from the audio signal source 11 is formed steeply by digital FIR filters 21L, 21R with linear phase, and a signal from which a high-pass range is cut off is supplied to the woofers 26L, 26R. The signal from which the high-pass area is cut off is reproduced from the woofers 26L, 26R at a listening position for only a time when Hass effect is effective by delaying from the reproducing audio signals of the full-range speakers 16L, 16R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker comprising a closed type full range speaker and a closed type woofer which is provided at a position spatially separated from the closed type loudspeaker so as to compensate for a low sound range lacking in the full range speaker. Regarding the device.

[0002]

2. Description of the Related Art For example, a vehicle audio system or a home AV system
In the sound reproducing device of the system, a full range speaker is often used as the speaker device.

However, this full-range speaker lacks a low-pitched sound range, so that it is difficult to obtain a dynamic reproduction sound space. Therefore, a bass woofer is provided separately from this full-range speaker, the bass range of the acoustic signal source to the full-range speaker is taken out, and the bass component is reproduced by the woofer to supplement the lacking bass range. Speaker devices have been proposed.

In this case, the hearth effect is used to give the listener a degree of freedom so that the listener can set the position of the woofer, which is spatially separated from the full-range speaker, at any position. Thus, the signal from the acoustic signal source is reproduced.

Here, the Haas effect means "delay time is 5
Below 0 msec, even if the level of the reflected sound is considerably higher than that of the direct sound, it does not cause echo interference. (Hass report (Acustica 1, 49-58, 1951)). Further, according to the law of the first wavefront (the effect of the preceding sound), it is known that "when the delay time exceeds 1 msec, the sound image is generated in the direction of the speaker which first radiates the acoustic signal". (Cremer Report (1948, vol.1.1.s.Hirzel Verlag,
Stuttgart.)).

According to Blauert's report, "In a anechoic room, when 1/3 octave band noise is presented from the speakers in front of and behind the subject, regardless of which is presented, 200 Hz or less It is impossible to specify, and at 200 to 500 Hz, if anything,
Localize forward. It has been pointed out.

From the above, the acoustic signal reproduced by the full-range speaker is branched, the high-frequency component is cut off to extract the low-frequency signal, and the hearth effect is obtained more than the reproduced sound of the full-range speaker. If the sound is reproduced by the woofer with a delay, the sound reproduced by the woofer can be heard by the listener as a sound from the same direction as the reproduced sound of the full range speaker, and the degree of freedom of the woofer installation position is increased.

FIG. 7 is a block diagram of an example of a conventionally proposed speaker device of this type. In FIG.
1 is an audio signal source, for example, a cassette tape player,
It is composed of a CD player and the like. In the case of this example, the audio signal source 1 outputs the stereo audio signals L and R in the state of analog signals. The left channel audio signal L
Is supplied to the left-channel full-range speaker 3L via the left-channel amplifier 2L, and the right-channel signal R is supplied to the right-channel audio amplifier 2L.
It is supplied to the right-channel full-range speaker 3R through R and reproduced as sound.

The signals L and R from the acoustic signal source 1 are also supplied to the mixer 4 and mixed, and the mixed signal is supplied to the analog low-pass filter 6 through a delay circuit 5 provided to obtain the Haas effect. As a result, high frequency components are cut off. Then, only the low frequency range component of the mixed signal from the low pass filter 6 is supplied to the woofer 8 via the audio amplifier 7, and the low frequency range is reproduced.

The full-range speaker is generally placed in front of the listener and the woofer is placed behind or beside the listener. As described above, according to the hearth effect, the bass signal is reproduced from the woofer later than the full-range speaker, so that the bass region is localized as if it was emitted from the direction of the full-range speaker.

[0011]

However, the above-mentioned conventional speaker device has the following problems because the analog low-pass filter 6 is used to block the high frequency components of the acoustic signal. It was

That is, FIG. 8 shows the frequency characteristics of an analog low-pass filter which has been conventionally used. The solid line shows the amplitude-frequency characteristic and the dotted line shows the phase-frequency characteristic. As can be seen from FIG. 8, in the case of the analog low-pass filter, it is impossible to cut off the high frequency range with a steep slope. In the case of FIG. 8, the degree of inclination is −
It is about 24 dB / oct.

As described above, since the analog filter cannot block the high frequency range with a steep slope, the cutoff frequency of the low-pass filter has to be set low, and it is necessary to reproduce the low band by the full-range speaker. there were. Incidentally, in the conventional case, as shown in FIG. 8, the cutoff frequency of the low-pass filter 6 is 140H.
It is set near z, and it is necessary to perform sound reproduction with a full-range speaker up to around this frequency, and it is necessary to use a large-sized full-range speaker.

Since the frequency characteristic of the low-pass filter is as described above, the level of the high frequency component to be cut off cannot be suppressed to a sufficiently low level, and the high frequency range is reproduced from the woofer 8, and this high frequency range component is reproduced. There is a flaw in hearing.

As shown in FIG. 8, in the case of the analog filter, the phase sharply changes in the transition region. For this reason,
If the low range of the full-range speaker interferes with the reproduced range of the woofer and the listener's listening position changes even slightly, the interference frequency changes significantly, resulting in a difficult-to-listen reproduced sound.

If the full-range speaker and the woofer are widely separated from each other, the influence of the above becomes large, and the reproduction acoustic space becomes hard to hear, and the delay amount of the delay circuit for obtaining the hearth effect becomes large, and its frequency is increased. Due to the characteristics and phase shift, in the conventional speaker device, the full-range speaker and the woofer cannot be widely separated.

It is an object of the present invention to provide a speaker device that solves the above problems.

[0018]

In order to solve the above-mentioned problems, the speaker device according to the present invention has a hermetically sealed full-range speaker 16 in correspondence with the reference numerals of the embodiments described later.
L and 16R, and sealed woofers 26L and 26R that are spatially separated from the full-range speakers, and a signal from the acoustic signal source 11 is supplied to the full-range speakers 16L and 16R and linear. A signal obtained by abruptly cutting off the high frequency range of the signal from the acoustic signal source 11 by the phase digital FIR filters 21L and 21R is
The signals are supplied to the woofers 26L and 26R, and at the listening position, the signals are reproduced from the woofers 26L and 26R with a delay from the reproduced acoustic signals of the full-range speakers 16L and 16R by the time when the hearth effect is established. Is characterized by.

[0019]

In the present invention having the above construction, the woofer 2
6L and 26R are supplied with signals in which the high frequency range of the signal from the acoustic signal source 11 is sharply cut off by the linear phase digital FIR filters 21L and 21R.

Then, the FIR filter 21 in this case
Since L and 21R are linear phases, the coefficients are symmetrical with respect to the center tap of the total number of taps used, and therefore a constant delay occurs before output without causing phase rotation in the signal. Due to the delay generated by the FIR filters 21L and 21R, the bass range reproduced from the woofers 26L and 26R by the hearth effect is localized as if it were emitted from the full range speaker. When the amount of delay generated by the FIR filters 21L and 21R is insufficient to obtain the hearth effect,
A delay circuit may be provided before or after the FIR filter.

[0021]

Embodiments of the speaker device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a speaker device according to the present invention. Also,
FIG. 2 is a speaker layout diagram in the case of this example.

In this example, as shown in FIG. 2, sealed full-range speakers 16L and 16R for the left and right channels are arranged in front of and to the left of the listener 30, and left and right behind and to the listener. Closed woofers 26L and 26R for the right channel are arranged.

Closed type full range speakers 16L and 16
R is a closed container such as a closed box 14L and 14R, respectively
In addition, the full-range speaker units 15L and 15R are attached. Also, a closed woofer 2
6L and 26R are closed containers 24 such as closed boxes
The woofer speaker units 25L and 25R are attached to the L and 24R, respectively.

In FIG. 1, 11 is an audio signal source, which has a digital audio signal output terminal such as a CD player, a mini disk player, a digital audio tape player, or the like. In the case of this example, the two-channel digital stereo audio signals DL and DR are obtained from the acoustic signal source 11.

Then, the digital signal DL of the left channel
Is converted into an analog audio signal L by the D / A converter 12L, and this is supplied to the speaker unit 15L of the closed type full range speaker 16L for the left channel via the audio amplifier 13L for the left channel,
Sound is played. Similarly, the digital signal DR of the right channel is converted into an analog audio signal R by the D / A converter 12R, and this is supplied to the speaker unit 15R of the closed type full range speaker 16R for the right channel through the audio amplifier 13R for the right channel. Then, the sound is reproduced.

The digital signals DL and DR from the acoustic signal source 11 are also linear phase digital FIR (Finite I).
npulse response) is supplied to the digital low-pass filters 21L and 21R, respectively, and the high frequency range is sharply cut off.

The FIR filters 21L and 21R in the case of this example are composed of a 1023 tap Butterworth type FIR filter having a Hamming window, a cutoff frequency of 400 Hz, and a cutoff characteristic inclination of -120d.
It is set to B / oct.

FIR filters 21L and 21R of this example
The passing frequency characteristic (amplitude-frequency characteristic) of is shown in FIG.
The impulse response is shown in FIG. It can be seen that the high range is sharply cut off and the level of the stop band is sufficiently suppressed.

Further, the FIR filters 21L and 21R of this example have a linear phase F of 1023 taps (1023 order).
Since it is an IR filter, the impulse response coefficient (weighting coefficient for each tap output) is symmetrical around the 512th tap number. Therefore, in the FIR filters 21L and 21R, 5 is applied to the input signal.
A delay of up to 12 taps is introduced in the output signal. Since one tap causes a delay of a unit delay time for one sample,
The sampling frequency of the digital audio signal is 44.
If it is 1 kHz, the delay time is about 11 msec. It is a linear phase, and there is no phase rotation of the signal when delayed.

The output signals of the FIR filters 21L and 21R are supplied to the D / A converters 22L and 22R, converted into analog signals, and the audio amplifier 23.
It is supplied to the speaker unit 25L of the left channel woofer 26L and the speaker unit 25R of the right channel woofer 26R via L and 23R, respectively.
Sound is played.

The delay time of about 11 msec in the FIR filters 21L and 21R is 4 m when converted into a sound wave propagation distance.
Is. Therefore, when the full-range speaker 16L and the woofer 26L and the full-range speaker 16R and the woofer 26R are arranged apart from each other by a distance shorter than this distance, the bass sound reproduced from the woofers 26L and 26R due to the hearth effect is heard by the listener 30. Localize forward.

As described above, linear phase digital FIR filters 21L and 21L are used as low-pass filters for extracting the acoustic signals reproduced by the woofers 26L and 26R.
Since R is used, the phase of the acoustic signal does not change, the phases of the signals reproduced from the full-range speaker and the woofer do not interfere, and the sound image localization and the sound field are not adversely affected. According to the experiment, even if the cutoff frequencies of the FIR low-pass filters 21L and 21R are increased to around 400 Hz as in the above example, the sound image localization and the sound field are not adversely affected.

Therefore, the closed type full range speaker 1
The 6L and 16R are only required to be able to reproduce the low sound range up to around 400 Hz, so that the sizes of these sealed full-range speakers 16L and 16R can be reduced.

Further, in the present invention, since the full range speaker and the woofer are both of the closed type, the output sound pressure level is lower than that of the bass reflex type, but it is possible to reproduce to a lower range. In the case of a bass reflex type speaker, a signal of opposite phase is output from the port, so that the phase changes abruptly in the low frequency range. Therefore, the sound image localization and the sound field are adversely affected, but the speaker device of the present invention does not have such a problem.

Closed type full range speakers 16L, 16R
It is possible to increase the spatial separation distance between the closed woofers 26L and 26R by increasing the number of taps of the FIR filter. , A delay circuit is separately provided for adjustment.

FIG. 5 is a block diagram of an embodiment in that case. That is, the FIR filters 21L and 2L of the example of FIG.
Digital delay circuits 27L and 27R are inserted between the 1R and the D / A converters 22L and 22R. This delay circuit 2
7L and 27R are composed of digital circuits that delay the digital signal by the required number of samples. Therefore, there is no phase rotation as in an analog delay circuit, and there is little interference between both speakers. Further, since the delay is in the state of the digital signal, the voice signal is not deteriorated.

In the above example, the woofers are provided for two channels corresponding to the two-channel stereo signals, respectively. However, like the conventional example described in FIG. It may be one.

FIG. 6 is a block diagram of an embodiment in that case. That is, in the example of FIG. 6, the acoustic signal source 1
The digital signals DL and DR from 1 are supplied to the mixer 41 and mixed. Then, the mixed signal from the mixer 41 is supplied to the low-pass filter 42 which is a linear phase digital FIR filter, and the high frequency range is sharply cut off. This FIR filter 42 is
It is configured similarly to the filters 26L and 26R.

The output signal of the FIR filter 42 is delayed by the digital delay circuit 43 and then supplied to the D / A converter 44 to be converted into an analog signal. Then, the analog signal from the D / A converter 44 is supplied to the sealed woofer 48 via the audio amplifier 45. The woofer 48 is configured by mounting a speaker unit 47 in a closed box 46.

The delay circuit 43 is provided when the amount of delay in the FIR filter 42 is insufficient to obtain the Hearth effect. For example, when the speaker device of this example is installed in a room of about 6 tatami mats ( If the delay time is 11 msec), this delay circuit 43 is used as in the example of FIG. 1 described above.
Is unnecessary.

In the example of FIG. 4 and the example of FIG. 5, the delay circuits 27L and 27R and the delay circuit 43 may be inserted before the FIR filters 26L and 26R and the FIR filter 42.

In the above example, the signal source 11 is described as a digital output. However, when the signal source 11 is an analog signal output, the analog output signal is A / D converted and is once converted into a digital signal. You can do this. Also, 2
Of course, the present invention can be applied to the case of multi-channel signals of more than channel signals.

[0043]

As described above, according to the present invention, the following effects can be obtained. 1. Because it can block the unnecessary high range with a steep slope,
The cut-off frequency of the low-pass filter composed of the FIR filter can be set high, and the size of the sealed full-range speaker can be reduced. 2. Since the level of the stop band (treble range) of the acoustic signal reproduced by the woofer is kept sufficiently low by the FIR filter, the extra treble range is not reproduced from the woofer. 3.
Since the phase does not rotate in the transition range, there is little interference between the reproduced sound from the full range speaker and the reproduced sound from the woofer. 4. Even if the distance between the two speakers is large, the hearth effect can be easily maintained by adjusting the delay time of the digital delay circuit. 5. If the woofer is placed near the listener, the reproduced sound pressure level will be small.

As is clear from the above effects, a small-sized closed type full-range speaker and a closed type woofer are spatially separated from each other, and a high frequency range of an acoustic signal is cut off sharply by a digital linear phase FIR filter. By reproducing the sound from the closed woofer with a delay for the time when the hearth effect is obtained at the listening position, it is possible to localize the sound image in the direction of the full-range speaker and supplement the lacking bass range. Furthermore, since the sound image is not localized in the closed woofer, the woofer can be installed anywhere.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of speaker arrangement of the speaker device of the example of FIG.

FIG. 3 is a diagram showing amplitude-frequency characteristics of the speaker device of the example of FIG.

FIG. 4 is a linear phase digital FIR used in the present invention.
It is a figure which shows the impulse response of a filter.

FIG. 5 is a block diagram of another embodiment of the speaker device according to the present invention.

FIG. 6 is a block diagram of still another embodiment of the speaker device according to the present invention.

FIG. 7 is a block diagram showing an example of a conventional speaker device.

FIG. 8 is a diagram showing frequency characteristics of a conventional speaker device.

[Explanation of symbols]

 11 acoustic signal source 13L, 13R audio amplifier 16L, 16R full-range speaker 21L, 21R FIR filter (low-pass filter) 23L, 23R audio amplifier 26L, 26R woofer 27L, 27R digital delay circuit 30 listener 41 mixer 42 FIR filter (low-pass filter) 48 woofer

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H04R 3/14 7346-5H H04S 1/00 B 8421-5H

Claims (3)

[Claims] 1. A hermetically sealed full-range speaker and a hermetically-sealed woofer arranged spatially apart from the full-range speaker, wherein a signal from an acoustic signal source is supplied to the full-range speaker and a straight line is provided. A signal obtained by abruptly cutting off the high frequency range of the signal from the acoustic signal source by the phase digital FIR filter is supplied to the woofer, and the reproduced sound of the full-range speaker is played for the time when the hearth effect is established at the listening position. A speaker device in which the signal is reproduced from the woofer after the signal is delayed. 2. An acoustic signal of a plurality of channels is output from the acoustic signal source, and a set of the full-range speaker and the woofer is provided for the number of channels, and
The speaker device according to claim 1, wherein the acoustic signals of the plurality of channels are reproduced. 3. The acoustic signal source outputs acoustic signals of a plurality of channels, the full-range speakers are provided for the number of the channels, and the acoustic signals of the plurality of channels are mixed, and the high level of the mixed signal. Digital FIR with the above range of linear phase
The speaker device according to claim 1, wherein the signal sharply cut off by the filter is a signal reproduced by a single woofer.