JPH01220599A - System for constituting acoustic field in car room - Google Patents

Abstract

PURPOSE:To realize presence and a feeling of spread equivalent to those of an actual concert hall by emitting stereo sounds from front right and left speakers and emitting sounds and initial reflection sounds, which are obtained by subjecting sounds to delay processing, from central right and left speakers directed to the front glass of a vehicle. CONSTITUTION:Stereo signals L and R of a stereo reproducing circuit 17 directly drive front left and right speakers 6 and 7. The output of an adder 28 is inputted to an initial reflection sound producing part 22 through a delay device 32, and the output and output signals L and R of the stereo reproducing circuit 17 are inputted to adders 34 and 35 of central left and right speakers 14 and 15 to drive central left and right speakers 14 and 15. Signals L and R of lines 18 and 19 are inputted to adders 34 and 35 also. Meanwhile, the output of the delay device 32 is inputted to a reverberation sound producing part 37, and the left channel side of the output is inputted to the adder 34 through a delay device 38. The acoustic signal of the right channel is given to the adder 35 through a coefficient device 39. Thus, presence and a feeling of spread equivalent to those of an actual concert hall are realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for configuring a desired sound field in the interior of a passenger car or the like.

Conventional technology Sound reproduction devices installed in vehicles such as passenger cars include monaural playback devices using AM wave receivers as sound sources, FM wave receivers, magnetic tape playback devices, and combination discs (CDs).
2. Description of the Related Art Stereo playback devices that use a playback device or the like as a sound source are widely used. Currently, in addition to the above-mentioned sound sources, the reproduction system installed inside passenger cars and the like includes front left and right speakers at the front of the vehicle interior, and rear left and right speakers at the rear. The front left and right speakers are located near the left and right ends of the instrument panel where various instruments are located,
They are installed on the left and right doors, respectively.

The rear left and right speakers are placed on the rear tray.

With this speaker arrangement, left channel stereo sound is reproduced from the front and rear left speakers, and right channel stereo sound is reproduced from the front and rear right speakers. This reproduction method allows the driver and passenger inside the vehicle to perceive the ``realism'' and ``spreading'' that are unique to stereo sound.

Problems to be Solved by the Invention The above-mentioned conventional techniques have the following problems compared to, for example, listening to an actual performance at a performance venue.

■At a listening position where good listening conditions can be achieved in a performance venue, such as near the center of the first floor seats, the sound localization direction is approximately in front of the listener. Furthermore, a configuration is adopted in which the reverberation time is relatively long. For example, in a listening room usually called a listening room, the reverberation time is approximately 4
It is known that the average height is about 1.5 to 25 m5 in concert halls with good acoustic design.

On the other hand, inside a car such as a passenger car, the reverberation time is 100
It is known that it is less than m5. As described above, there is a large difference in reverberation time between a normal performance venue and a car interior.

Furthermore, in a performance venue, the sound generated on the stage is reflected multiple times within the performance venue, so that the reverberant sound reaches the listener from all directions. This aspect of reverberant sound is also an important element in achieving the above-mentioned ``sense of realism'' and ``sense of spaciousness''.

The purpose of the present invention is to provide a vehicle interior sound field configuration method that solves the above-mentioned technical problems and provides good reproducibility in terms of "realism" and "sense of spaciousness" even in the vehicle interior. be.

Means for Solving the Problems The present invention provides a front left speaker, a front right speaker, and a center left speaker located between these front left and right speakers and facing the windshield of the vehicle. A center right speaker is prepared, the front left and right speakers generate stereo sound, and the center left and right speakers generate sound and early reflected sound obtained by delay processing the sound. This is an in-vehicle sound field configuration method.

Further, in the vehicle interior sound field configuration method of the present invention, reverberation sound may be generated from the central left and right speakers in addition to sound and early reflected sound.

According to the present invention, stereo sound is generated from the front left and right speakers arranged in the vehicle interior, and the sound is emitted from the center left and right speakers arranged between the front left and right speakers, and the sound is emitted for a predetermined time. A delayed early reflection sound is generated. These central left and right speakers are arranged facing the windshield of the vehicle.

With this configuration, listeners inside the vehicle can localize the sound almost directly in front of them due to the action of the front left and right speakers and the center left and right speakers, and can also obtain a good "sense of spaciousness" due to the early reflected sound. can. Furthermore, if reverberation sound is generated from the center left and right speakers in addition to sound and the early reflected sound, the "sense of presence" and "sense of spaciousness" during listening can be further improved.

Embodiment FIG. 10 is a graph showing temporal changes in the sound that reaches the listener when the sound generated from the stage is listened to at a good listening position such as a concert venue, and FIG. 2 is a graph schematically showing a temporal change in sound reaching a listener in a vehicle interior 5, which is attempted to be realized by the following. The object of the present invention will be explained with reference to FIGS. 10 and 11. When listening to music at a performance venue or the like, the sound generated on the stage reaches the listener as a direct sound S1 at a volume level a1 after a time Wl from the time of generation.

After the direct sound S1 arrives, the early reflected sound S2 arrives at time w 2 f&. This early reflected sound S2 is a sound generated on the stage that is reflected once or twice at most on the walls in front and behind the stage, the inner wall of the performance venue, etc., and reaches the listeners. The time it takes for such sound to reach the listener and the degree of attenuation vary depending on the reflecting position and the state of the wall surface at the reflecting position, and the distribution is as shown in FIG. 10, an example of which is shown. It should be noted that the early reflected sounds S2 in FIG. 10 do not include those whose volume levels are relatively low when they reach the listener.

Attenuated reverberation sound S3 shown by a two-dot chain line reaches the end of this early reflected sound S2. The time from the arrival time of the direct sound S1 to the end time of the reverberant sound S3 is 1.5 to 2 seconds in a performance venue with good acoustic design.The present invention shows the time change of the sound reaching the listener as shown in Fig. 9. This is what we are trying to realize as the optimal mode shown in .

FIG. 11 shows how the arriving sound changes over time, which the present invention actually attempts to realize. After the generation of the direct sound 81 to be heard, an early reflected sound S2 is generated from a delay time Dl f&. This early reflected sound S2 is.

Based on the direct sound S1, from its level a1 to smaller levels ql, q2 . ..., qn, with time intervals T2, T3 .・・・
. , Tn.

In this embodiment, the reverberation sound S3 is generated after a delay time D2 from the start time of the early reflected sound S2.
are left channel reverberation sound S3L and right channel reverberation sound S3
R, and a delay time D3 is provided between them.

FIG. 1 is a diagram showing an example of the configuration of an in-vehicle stereo sound reproduction device according to an embodiment of the present invention, FIG. 2 is a plan view showing the configuration of this embodiment, and FIG. It is a side view showing the composition of an example. This embodiment will be described with reference to FIGS. 1 to 3 [ ]. For example, a driver 2 and a passenger 3 ride in a vehicle 1 such as a passenger car, facing toward an instrument panel 4, that is, facing forward.

In the cabin 5 of the vehicle 1, a front left speaker 6 and a front right speaker 7 are connected to, for example, a front left door 8 and a front right door 9.
They are respectively attached to face the inside of the vehicle compartment 5.

Further, a rear left speaker 11 and a rear right speaker 12 are attached to the rear tray 10 of the vehicle 1 so as to face the rear glass 13. Further, a center left speaker 14 and a center right speaker 15 are mounted near the center position of the instrument panel 4 in the left-right direction so as to face the windshield 16.

Each such speaker 6.7; 11, 12; 14.15
For example, a stereo playback device 17 such as an FM wave receiver, a magnetic tape stereo playback device, or a compact disk playback device is connected to. The audio signal from the stereo reproduction device 17 is supplied to the amplifier 20 via the line 18.19, and stereo sound is generated from the front left and right speakers 6.7.

On the other hand, the analog audio signal from the stereo recycling bag M17 is sent to an analog/digital converter (hereinafter referred to as an A/D converter).
21, the signal is supplied to a signal processing device 22 having a configuration as described below. The digital signal from the signal processing bag T122 is converted into an analog signal by a digital/'analog converter (hereinafter referred to as a D/A converter) 23, and then sent to the center left and right speakers 14, 15 and the rear left and right speakers via amplifiers 24 and 25. Sound is generated from 11.12.

FIG. 4 is a block diagram showing the basic electrical configuration of the in-vehicle stereo sound reproduction device. Mark 9 on Figure 4,
The electrical configuration of this embodiment will be explained. Stereo recycling bag'! The stereo sound signals R and R from 117 are attenuated by attenuation coefficients gl and g2 through coefficient multipliers 26 and 27, respectively, and then added by an adder 28 to become a monaural signal.

A low-frequency component of the monaural signal from the adder 28 is extracted by a low-pass filter (hereinafter abbreviated as LPF) 29, and the low-frequency component is extracted from the monaural signal from the adder 3, which is connected to rear left and right speakers 11 and 12.
0.31 respectively.

Further, the output of the adder 28 is inputted to an early reflected sound generating section 33 configured as described below via a delay device 32 having a predetermined delay time D1 as described later. The output of the early reflection sound generation section 33 is output from the center left and right speakers 14.15.
is applied to adders 34 and 35 connected to. The adders 34 and 35 receive the stereo sound signals on the lines 18 and 19.

R is given respectively.

On the other hand, the output of the delay device 32 passes through a delay device 36 having a delay time D2, which is provided separately, and is input to a reverberation sound generation section 37 having a configuration as described below.

The left channel side of the output of the reverberant sound generation section 37 passes through a delay device 38 with a delay time D3, which is provided separately, and is then connected to the adder 30.
given to. On the other hand, the sound signal of the right channel is ;lf
It is applied to the adder 31 after passing through three coefficient multipliers of the coefficient g3. Although the effect of the present invention can be achieved with only the reverberation sound, which generates not only the reverberation sound from the ridge left and right speakers 11 and 12 but also the low frequency front from the LPE 2a,
The volume is 6.7 from the front left and right speakers and 14 from the center left and right speakers.
, 1 is weak compared to sea urchins, and the sound source is deflected toward the front of the vehicle. To compensate for this situation, low frequency sounds are generated from the rear left and right speakers 11 and 12. The outputs of this delay unit 38 and coefficient unit 39 are individually given to the adders 34 and 35.

FIG. 5 is a block diagram showing a specific example of a configuration related to the signal processing device 22. As shown in FIG. This embodiment will be described with reference to FIG. The stereo sound signals R and R from the stereo reproduction device 17 are respectively LPFs 40 and 41 and a sample hold circuit (hereinafter abbreviated as S/H circuit) 42.
43 to the 1, A/'D converter 21. The output of the A/D converter 21 is given to a signal processing device 22. The signal processing device 22 includes an early reflected sound generation section 33, an acoustic sound reproduction section 37, and an LPF 29 shown in FIG. This signal processing device 22 is provided with a delay storage section 44 for temporarily saving acoustic signals in order to perform delay processing as will be described later, and is connected to the delay storage section 44 by an address bus 45 and a data bus 46.

The output of the signal processing device 22 is sent to a D/A converter 23a that constitutes the D/A converter 23 shown in FIG.

23b, and each output is LPF47°48
; 49 and 50, and are output to the center left and right speakers 14 and 15 and the rear left and right speakers 11 and 12, respectively.

FIG. 6 is a block diagram showing an example of the configuration of the early reflected sound generation section 33. The early reflected sound generation section 33 will be explained with reference to FIG. The stereo sound signal R converted into a digital signal by the A/D converter 21 as shown in FIG. Ru. After this, the acoustic signal given the delay time D1 by the delay device 32 is
As shown in FIG. 4, the signal is input to the early reflected sound generation section 33.

As shown in FIG. 6, the early reflected sound generation section 33 generally includes n delay devices DLI, DL2 . ..., DLn (generally referred to by the reference symbol DL when necessary) are connected in series, and the output of each delay device DL has an attenuation coefficient Ql.
, Q2. -..., qn coefficient multiplier AI, A2. ..., A
n, their outputs are added by an adder 51, and converted into an analog signal by a D/A converter 23.

Delay time T1 of the delay device DL. T2. ..., T"l
is the time interval 1iT2. in the early reflected sound S2 which is intended to be realized in the present embodiment described with reference to FIG. T3
．． .
2. T3. ..., each sound level ql with Tn,
q2. ..., qn.

FIG. 7 is a block diagram showing the configuration of the reverberation sound generation section 37. The reverberation sound generation section 37 will be explained with reference to FIG. As explained with reference to FIG. 4, the reverberant sound generating section 37 receives a signal which is given the delay time D1 by the delay device 32 and then given a delay time D2 by the delay device 36. Such a delay time D2 is the 10th
The delay time D2 is selected as described with reference to the figure.

In general, it is known that the lower the frequency of the sound generated, the longer the reverberation time, and this fact also applies to the auditory senses in actual performance venues, etc., as explained with reference to Figure 10. It is included.

Therefore, in the reverberant sound generation section 37 of this embodiment, the input signal is divided into, for example, three bands using an LPF 52, a band pass filter (hereinafter abbreviated as BPF) 53, and a bypass filter (hereinafter abbreviated as HPF) 54. All-pass filter (hereinafter referred to as AP) has a configuration as described below.
(abbreviated as F) 55, 56, and 57, the attenuation rate is changed individually. That is, the output from the LPF 52 has a longer delay time to slow down the attenuation, and the output from the bypass filter 64 has faster attenuation. Further, the output of the BPF 53 is selected depending on the degree of attenuation between them. The outputs of APFs 55 to 57 are added by an adder 58.

On the other hand, for example, the APF 55 has the function of gradually decreasing the level of the output from the LPF 52 at a predetermined period. This effect is due to the residual APF5
The same applies to 6.57. APF55 like this
For a periodic level damping action of ~57, a single stage of A
In PFs 55 to 57, the density of sampling for attenuating the level is coarse, and it may not be possible to obtain a smooth sense of level attenuation in auditory senses where the sound level gradually attenuates.

Therefore, in this embodiment, there are two APs in the adder 58.
F59.60 is provided to increase the sampling density and obtain a smooth level attenuation pattern.

FIG. 8 is a block diagram showing an example of the configuration of the APFs 55 to 57, 59, and 60. The APF 55 will be explained as an example with reference to FIG. The signal from the LPF 52 is given an attenuation coefficient -g by a coefficient multiplier 61 and is given to an adder 62 .

On the other hand, the input to the coefficient multiplier 61 is input to an adder 63, and the output thereof is given a delay time by a delay device 64.

3! ! The output of the extender 64 is input to a coefficient unit 65, and the output of the coefficient unit 65 is input to the adder 62. delay device 64
The output is input to the adder 63 via the coefficient unit 66. Here, the damping coefficients of the coefficient multipliers 61, 65, and 66 are -g, 1-g2, respectively. g is chosen to have the same damping coefficient g.

FIG. 9 is a graph showing changes in the output of the APF 55. The operation of the APF 55 will be described with reference to FIG. 9. The level of the input signal of the coefficient multiplier 61 is (1)
Then, the level of the output of the adder 62 following the coefficient multiplier 61 is )-g).

On the other hand, the input signal of the coefficient multiplier 61 is input to a delay device 64 via an adder 63, and a delay time is given thereto. delay device 6
The output signal of No. 4 is outputted via the coefficient unit 65 and the adder 62, but is also input to the coefficient unit 66, and fed back to the delay unit 64 via the adder 63. At this time, the input signal level of the delay device 64 is (gl).

Next, when this signal is further delayed by the delay device 64 and inputted again via the coefficient unit 66 and the adder 63, its level is (g2) when viewed at the output terminal of the delay device 64. It has become.

In this way, each time the input signal cycles through the closed circuit consisting of the adder 63, delay device 64, and coefficient multiplier 66, the level becomes (g'l (i=1.2..., n). This state is shown in FIG.

The attenuation coefficients of the coefficient multipliers 61, 65, and 66 of the APF 55 are -g, 1-g2, respectively. g and the delay time of the delay device 64 are:
It is set based on the formula below.

g = L O...(1) n x D = W r -< 2
) LO: Attenuation lower limit level (for example, 60 dB attenuation)
Wr: The desired total reverberation time delay time is experimentally determined so as to provide a smooth attenuation mode corresponding to the frequency band of the signal input to the APF 55.

Such a configuration is applicable not only to APF55 but also to the remaining APF5.
The same applies to 6.57 and 59.60, and the time period and attenuation rate g are appropriately selected with respect to the desired characteristics.

When using an in-vehicle stereo sound reproduction device having such a configuration, left and right channel stereo sound is reproduced from the front left and right speakers 6.7 and the center left and right speakers 14.15, and the direct sound shown in FIG. The delay time D is set by the delay device 32 shown in FIG.
1 is given to the early reflected sound reproduction section 33.
Then, the early reflected sound S2 shown in FIG. 11 is generated, and is generated from the central left and right speakers 14 +' 15.

As mentioned above, the sounds from the center left and right speakers 14, 15 and the rear left and right speakers 11, 12 collide once with the windshield 16 and the rear glass 13 and are transmitted to the vehicle interior 5.
Because the sound enters the inside of the room, the sound localization direction for the listener is approximately in front of the listener, which is the same as the localization direction when actually listening at a concert hall, etc., and a natural listening experience is obtained. Further, by generating the early reflected sound S2, a "sense of depth" in front of the listener can be obtained, similar to when listening at an actual performance venue.

On the other hand, the signal given the delay time D1 by the delay device 32 is given a delay time D2 by the delay device 36, and is given to the reverberation sound generation section 37. The acoustic signal that is gradually attenuated by the reverberant sound generation section 37 is divided into a left channel signal and a right channel signal R, and the right channel signal R is inputted to a coefficient unit 39 and then inputted to an adder 31.35. Ru. On the other hand, the left channel signal is input to the delay device 38, given a delay time D3, and input to the adders 35 and 34.

That is, the reverberant sound from the reverberant sound generator 37 is also generated from the central left and right speakers 14,15.

On the other hand, the bass signal from the LPF 29 is also input to the adders 30 and 31. In other words, the rear left and right speakers 11 and 12 generate reverberant sound from the reverberant sound generator 37 and bass sounds from the LPF 29.

In this way, reverberant sound is generated from the center left and right speakers 14.15 and the rear left and right speakers 11.12, and bass sounds are generated from the rear left and right speakers 11.12. A sound field inside the vehicle compartment 5 created by such a sound generation method is shown in 12121. FIG. 13 is a diagram showing the state of the sound field in the vehicle interior based on the conventional example when only the front left and right speakers 6.7 and the rear left and right speakers 11.12 are used and only stereo sound is generated from these.

FIG. 12 (1) and FIG. 13 (1) are views corresponding to a plan view of the vehicle compartment 5. According to FIG. 12(1), it can be understood that the sound reaches the listener in a relatively frontal direction and over a wide angle range.

FIG. 12(2) and FIG. 13(2) are views corresponding to side views of the vehicle compartment 5. By comparing these, it will be understood that the direction of arrival of the sound to the listener is distributed in the front direction of the listener in the vehicle interior 5, and the preferable hearing sensation as described above is obtained.

FIG. 12(3) and FIG. 13(3) are views corresponding to rear views of the vehicle compartment 5. Comparing these figures, it can be seen that the sound is reaching the listener from all directions.
It can be seen that the "sense of realism" and "sense of spaciousness" have been significantly improved.

As another embodiment of the present invention, the front left and right speakers 6.7 may be provided near both left and right ends of the instrumental panel 4, and instead of the configuration in which stereo sound is generated from the center left and right speakers 14.15. , adder 28 in FIG.
The output may be input to adders 34 and 35 to generate monaural sound. It has been confirmed that the effects of the present invention can be achieved even in this case. Further, the present sound field reproduction method may be used by being switched from a normal stereo reproduction method using a changeover switch or the like.

Effects of the Invention As described above, according to the present invention, when stereo sound is reproduced inside the cabin of a vehicle, it is possible to achieve a "real 4!5J" or "spreading feeling" that is equivalent to when listening at an actual concert venue. can do.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of an embodiment of the present invention.
3 is a side view of the vehicle 1, FIG. 4 is a block diagram showing the basic configuration of this embodiment, and FIG. 5 is a concrete configuration of the configuration shown in FIG. 4. Block diagram showing an example, No. 6
The figure is a block diagram showing an example of the configuration of the early reflected sound generation section 33,
FIG. 7 is a block diagram showing a configuration example of the reverberation sound generation section 37,
FIG. 8 is a block diagram showing a configuration example of the APF 55, FIG. 9 is a graph explaining the operation of the APF 55, FIG. 10 is a graph showing temporal changes before reaching the performance venue, and FIG.
The figure is a graph showing the temporal change in arriving sound in this embodiment, and FIGS. 12 and 13 are diagrams explaining the effects of this embodiment. 5... Vehicle interior, 6... Front left speaker, 7... Front right speaker, 11... Rear left speaker, 12... Rear right speaker, 13... Rear glass, 14... - Center left speaker, 15... Center right speaker, 16... Windshield, 17... Stereo playback device, 22...
・Signal processing device, 26, 27, 39, 61, 65.66
...Coefficient unit, 29.40.41.47,48,49.
52...LPF, 32.36, 38.64...Delay unit, 33...Early reflected sound generation section, 37...Reverberation sound generation section Agent Patent attorney Number of strokes Keiichi 2nd mouth M 3 Figure ! Figure 7 Figure N9 June 4, 1986

Claims (2)

[Claims] (1) Prepare a front left speaker and a front right speaker in the vehicle interior, and a center left speaker and a center right speaker placed between these front left and right speakers and facing the windshield of the vehicle, A sound field configuration method for a vehicle interior, characterized in that stereo sound is generated from front left and right speakers, and sound and early reflected sound obtained by delay processing the sound are generated from center left and right speakers. (2) The vehicle interior sound field configuration method according to claim 1, wherein the center left and right speakers generate reverberation sound in addition to sound and early reflected sound.