JPH01220600A - System for constituting acoustic field in car room - Google Patents

Abstract

PURPOSE:To realize presence and a feeling of spread by providing front left and right speakers which emit stereo sounds, central left and right speakers arranged in the middle between them, and rear left and right speakers directed to the rear glass of a vehicle and emitting reverberation sounds from rear left and right speakers. CONSTITUTION:Stereo signals L and R are attenuated through coefficient devices 26 and 27 and are added by an adder 28 to obtain a monaural signal, and the low band component is taken out by an LPF 29 and is inputted to adders 30 and 31 of rear left and right speakers 11 and 12 directed to the rear glass of the vehicle. The output of the adder 28 is inputted to an initial reflection sound producing part 33 through a delay device 32, and the output is inputted to adders 34 and 35 of 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 30 through a delay device 38. The reverberation signal on the right channel side is given to the adder 31 through a coefficient device 39. Thus, rear left and right speakers are driven to realize presence and a feeling of spread equivalent to that of an actual concert hall.

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 vehicle such as a passenger car.

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 source, the reproduction system installed in the interior of a passenger car or the like includes front left and right speakers in the front of the vehicle interior, and rear left and right speakers in the rear. The front left and right speakers are installed near both left and right ends of the instrument panel where various instruments are placed, and on the left and right doors, respectively.

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

With this speaker arrangement, the front and rear left speaker
The left channel stereo sound is played from the power source, and the right channel stereo sound is played 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 Loo.
It is known that it is less than ms. 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 presence" 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 "spread S" even in the main room. be.

Means for Solving the Problems The present invention provides a front left speaker and a front right speaker that generate stereo sound in a vehicle interior, a center left speaker and a center right speaker disposed between these front left and right speakers, This is an in-vehicle sound field configuration method characterized by having a rear left speaker and a rear right speaker arranged facing the rear window of the vehicle, and generating reverberant sound from the rear left and right speakers.

In the present invention, the center left and right speakers may be arranged toward the windshield of the vehicle. In such a case, the front left and right speakers generate stereo sound, and the center left and right speakers generate sound and early reflection sound. In addition to this, reverberant sound may also be generated, and in addition to the reverberant sound, the bass range of the stereo sound described above may be generated from the rear left and right speakers. .

Function According to the present invention, front left and right speakers, center left and right speakers, and rear left and right speakers arranged in the vehicle interior are used. At this time, stereo sound is generated from the front left and right speakers, and sound is generated from the center left and right speakers. In addition, the rear left and right speakers are placed facing the vehicle's rear window and generate reverberant sound. As a result, the direction of arrival of sound reaching the listener from the rear moves upward, making it possible to achieve a suitable hearing sensation.

The center left and right speakers may be placed facing the windshield of the vehicle, and sound and early reflected sound may be generated from the center left and right speakers. In such a case, the arrival of sound arriving from the front side of the listener may be The direction is located in front of the listener, and the localization direction of the sound can be lifted upward compared to the case where the front left and right speakers are provided near the front door or the instrument panel of the vehicle. This dramatically improves the sense of presence and expansiveness of the auditory sense inside the vehicle.

Further, in addition to sound and early reflected sound, reverberant sound may be generated from the central left and right speakers, and in such a case, the audibility is further improved. In addition to the reverberant sound, the rear left and right speakers may generate the low frequency range of the stereo sound described above. In such a case, compared to the case where only the reverberant sound is generated from the rear left and right speakers, It is possible to prevent the volume from becoming lower than the volume from the front left and right speakers and the center left and right speakers.

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 arrival of this direct sound S1, after a time W2, the early reflected sound S2
is reached. 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 condition of the wall surface at the reflecting position, resulting in a distribution as shown in FIG. 1O. 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.

After this initial reflected sound S2, a decaying reverberant sound S3 shown by a two-dot chain line arrives. 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 hall 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. II! Direct sound S taken
After the occurrence of 1, the initial reflected sound S from the delay time D 1 tJi
2 is generated. Based on the direct sound S1, this early reflected sound S2 has a level a1 to a smaller level q.
l, q2. . . . rqn are generated, and there are time intervals T2, T3 . . . . . . is a signal provided with 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.
is the left channel '8. It is divided into reverberant sound S3L and right channel reverberant sound 83R, 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. With reference to FIGS. 1 to 3,
This example will be explained. For example, a driver 2 and a passenger 3 ride in a vehicle 1, such as a passenger car, facing toward an instrumental panel 4, that is, facing forward. Inside the cabin 5 of the vehicle 1, a front left speaker 6 and a front right speaker 7 are mounted, for example, on a front left door 8 and a front right door 9, respectively, facing into the cabin 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 playback device 17 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. Signal processing bag r! ! The digital signal from 22 is converted into an analog signal by a digital/analog converter (hereinafter referred to as a D/A converter) 23, and is output from the center left and right speakers 14.15 and the rear left and right speakers 11.12 via an amplifier 24.25. Generates sound.

FIG. 4 is a block diagram showing the basic electrical configuration of the in-vehicle stereo sound reproduction device. With reference to Figure 4,
The electrical configuration of this embodiment will be explained. The stereo sound signals R and R from the stereo reproduction device 17 are attenuated by attenuation coefficients gl and g2 via 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 with a separately determined delay time D2, 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 separately determined delay time D3, and then passes through the adder 30.
given to. On the other hand, the right channel audio signal is applied to the adder 31 through a coefficient multiplier 39 with an attenuation coefficient g3. Not only the reverberation sound from the left and right speakers 1112 of the t* section but also the low-frequency sound from the LPE 2a are generated as follows.
Although the effect of this case can be achieved with reverberant sound alone, the volume of the front left and right speakers is 6.7 and the center left and right speakers are 14.1.
This is because the sound image is weaker than that of No. 5, and the sound image is deflected toward the front of the vehicle. To compensate for this situation, rear left and right speakers 11
．． 12 generates low frequency sound. The outputs of the delay device 38 and three coefficient devices 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 Wi17 are LPF40.41 and sample hold circuit (hereinafter abbreviated as S/8 circuit) 42, respectively.
．． Via 43.

The signal is applied to the A/D converter 21. The output of the A/D converter 21 is given to a signal processing device 22. Signal processing device 22
is configured to include the early reflected sound generation section 33, the reverberation sound reproduction section 37, and the 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
; 49.50, and is 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. As shown in FIG. 5, the stereo audio signal R converted into a digital signal by the A/D converter 21 is synthesized by an adder 28 as shown in FIG. 4, and is made into a monaural signal. After this, delay device 3
The acoustic signal given the delay time D1 by the fourth
As shown in the figure, the first 1111 reflected sound is input to the 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 Al, A2 . ..., A
n, their outputs are added by an adder 51, and converted into an analog signal by a D/A converter 23.

The delay times Tl, T2 . of the delay device DL. . . , Tn are the time intervals T2 . T3.
.
．． T3. ..., each sound level ql, q with Tn
2. ..., 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 generation 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 HPP) 54. , an all-pass filter (hereinafter referred to as AP
(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
With PFs 55 to 57, the density of sampling for attenuating the level is low, 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, two stages of APs are provided after 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 APRs 55-57, 59, 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.

! ! The output of the extender 64 is input to the coefficient unit 65.
The output of 5 is input to the adder 62. The output of the delay device 64 is input to the adder 63 via the coefficient unit 66.

Here, the damping coefficients of the coefficient multipliers 61, 65, and 66 are respectively -g+1-g'', and g is selected 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 l.

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-g'', g and the delay time of the delay unit 64, respectively.
It is set based on the formula below.

g'=LO...(1) nXD=Wr-(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, 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 system 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. It reaches the listener as sound S1. Next, the delay time D is determined 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 emitted from the central left and right speakers 14 and 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 performance venue, etc., and a natural listening sensation can be obtained. Furthermore, by generating the early reflected sound S2, "depth control" 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 generating section 37 is separated into a left channel signal and a right channel signal R, and the right channel signal R is input to three coefficient multipliers, and is input 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 low frequency signal from the LPF 29 is also input to the adders 30 and 31. That is, the rear left and right speakers 11 and 12 generate the TA reverberation sound from the reverberation sound generation section 37 and the bass sound 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 within the vehicle compartment 5 created by such a sound generation method is shown in FIG. 12. FIG. 13 is a diagram showing the stratification 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. M12 (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 ends of the instrumental panel 4 in the left and right direction. Also, instead of the configuration in which stereo sound is generated from the center left and right speakers 14, 15, the 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.

As described above, the present invention can achieve the same "realism" and "spreading feeling" as when listening to stereo sound in an actual performance venue when stereo sound is reproduced inside the cabin of a vehicle. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a configuration example 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 figures are graphs showing temporal changes in arriving sound in this embodiment, and FIGS. 12 and 13 are diagrams illustrating the effects of this embodiment. 5... Vehicle interior, 6... Front right 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 1G12 Grass 3 Figure 7 Figure 9 Left

Claims (4)

[Claims] (1) A front left speaker and a front right speaker that generate stereo sound in the vehicle interior, a center left speaker and a center right speaker placed between these front left and right speakers, and a center left speaker and a center right speaker placed toward the rear glass of the vehicle. A sound field configuration method for a vehicle interior is characterized in that a rear left speaker and a rear right speaker are prepared, and reverberant sound is generated from the rear left and right speakers. (2) The vehicle interior sound field configuration method according to claim 1, wherein the center left and right speakers are arranged toward the windshield of the vehicle to generate sound and early reflected sound. (3) The vehicle interior sound field configuration method according to claim 2, wherein the center left and right speakers generate reverberation sound in addition to sound and early reflected sound. (4) The vehicle interior sound field configuration method according to claim 3, wherein in addition to the reverberant sound, the rear left and right speakers generate the low frequency range of the stereo sound.