JPH027699A - Acoustic reproducing device with sound field correction function - Google Patents

Abstract

PURPOSE:To attain acoustic reproduction with high fidelity by radiating a sound of the same level is as and of the opposite phase to a reflecting sound from a main speaker to a listening position provided near the listening position from an auxiliary speaker giving only a direct sound so as to make them coincident at the listening position. CONSTITUTION:Auxiliary speakers SPHL, SPHR are provided toward left/right ears of a listener 12 to a head rest 15 of a seat 14 down which the listener 12 sits and only direct sounds HL, HR of the sound from the auxiliary speakers are made respectively incident in the left/right ears of the listener 12. Then the acoustic signal is retarded by a difference between a time when the reflected sound radiated from the main speaker is propagated up to the listening position and a time when the direct sound from the auxiliary speakers is propagated up to the listening position, the result is introduced and the sound of the same level as and of the opposite phase to the reflected sound radiated from the main speaker is radiated from the main speaker so that they are made coincident at the listening position. Thus, the reflected sound from the main speaker is cancelled and the sound is reproduced with high fidelity.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is suitably implemented in a vehicle-mounted sound reproducing device, etc., and has a sound field correction function that can reduce the influence of reflected sound from walls, etc. The present invention relates to a sound reproduction device having a sound reproduction device.

Conventional Technology In an environment where reflected sound is likely to occur, such as the interior of an automobile, where glass or the like is used, the sound from the speaker 1 is transmitted directly to the listener 2, as shown in FIG. At the same time, it also arrives as reflected sound R from the wall surface 3 and the like. The relationship between these direct sounds and reflected sounds R is as follows in Article 811J.
As indicated by
only to arrive late.

In a typical conventional technique, the reflected sound R is reduced using a sound reproducing apparatus 10 having a configuration as shown in FIG. That is, the acoustic signal from the acoustic signal source 4 is
The acoustic signal is delayed by the time closing τ in the delay circuit 5, the coefficient is calculated in the amplifier circuit 6 so that the acoustic signal has a level equal to the level of the reflected sound R, and the calculation result is subtracted from the acoustic signal in the subtraction a7. Ru. In this way, the acoustic signal derived from the subtracter 7 via the power amplifier circuit 8 to the speaker 1 includes a signal -R of the same level and opposite phase, corresponding to the reflected sound R, as shown in FIG. , thereby reducing the influence of the reflected sound R and making it possible to reproduce sound with high fidelity.

Problems to be Solved by the Invention In the prior art as described above, as shown in FIG. When the level of the sound is sufficiently lower than that of direct sound, high-fidelity sound reproduction can be achieved. , the reflected sound R;t may be louder than the direct sound. In such a case, mutual interference occurs between the direct sound and the reflected sound -Ra, and the timbre of the direct sound is inhibited, causing the speaker 1
The fidelity of the sound reproduced from the IO will be compromised.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sound reproduction device having a sound field correction function that can reduce the influence of sound reflected from walls and the like and reproduce sound with high fidelity.

Means for Solving the Problems The present invention comprises: a main speaker; an auxiliary speaker that provides only direct sound to a listening position; a delay means for delaying by a difference τ3−τ1 between a first propagation time τ3 required for the direct sound from the auxiliary speaker to propagate to the listening position and a second propagation time τ1 required for the direct sound from the auxiliary speaker to propagate to the listening position; , an inverse function 17 of the transfer function G8 of the main speaker to the listening position of the reflected sound from the main speaker (17 Transfer function of auxiliary speaker to position G9
a second amplifier circuit having a second transfer function that is an inverse function of 1/G, the delay means and the first and second amplifier circuits are connected in series to transmit the acoustic signal to an auxiliary speaker. This is a sound reproduction device having a sound field correction function.

Function According to the present invention, a main speaker is provided facing the listening position, and an auxiliary speaker is provided near the listening position to provide only direct sound to the listening position. The acoustic signal is applied directly to the main speaker and also to the auxiliary speaker via a series-connected delay means and first and second amplification circuits.

The delay means allows the direct sound from the auxiliary speaker to propagate to the listening position within a first propagation time required for the reflected sound emitted from the main speaker to propagate to the listening position. The difference τ, −τ from the second propagation time τ required for
The acoustic signal is delayed by 1 and derived. Further, the first amplifier circuit has a first transfer function that is an inverse function 1/G7 of the transfer function 67 from the main speaker to the listening position of reflected sound, and the second amplifier circuit has a first transfer function that is an inverse function 1/G7 of the transfer function 67 from the main speaker to the listening position of the reflected sound. The inverse function 1 of the transfer function Gll from the speaker to the listening position of direct sound,
' G s has a second transfer function.

However, the auxiliary speaker emits a reverse sound at the same level as the sound f) reflected sound emitted from the main speaker so as to match the sound at the listening position. As a result, the reflected sound from the main speaker is canceled, and only the direct sound from the main speaker can be heard at the listening position, and the sound field is corrected so that the listening position becomes the optimal listening position. It is possible to perform high-fidelity sound reproduction.

Embodiment FIG. 1 is a plan layout diagram showing the configuration of a sound reproduction device 11 according to an embodiment of the present invention. The sound emitted from the main speaker SPF placed in front of the listener 12 is
The direct sounds DL and D shown by solid lines, the reflected sounds RL and R from the wall surface 13 shown by broken lines, and the left and right ears E of the listener 12, .

The light is incident on E and l, respectively.

On the other hand, the headrest 1 of the seat 14 where the listener 12 is seated
5 is provided with auxiliary speakers 5PHL, 5PHR facing the left and right ears Ec, E- of the listener 12, and the sound from the auxiliary speakers 5PHL, SPH, t is shown by imaginary lines in FIG. Thus, only the direct sounds HL, H, enter the left and right ears E, , E, of the listener 12, respectively.

In this Figure 1, the direct sound Dt from the main speaker SPF
,,D The true path lengths are respectively expressed as l IL+ l IJl, and the path lengths of the reflected sound RLR7 from the main speaker SPF are respectively expressed as l 2L+ 12M, and from the auxiliary speakers S P HL, S P He direct sound H
L.

The path length of each Hll is represented by 'ffL+1111.

For example, if an acoustic signal is simultaneously applied to the main speaker SPF and the auxiliary speaker SP [(, at time 1.
As shown in FIG. 2, the direct sound H5 first reaches the ear E8 of the listener 12 after a time τ1, and then the direct sound H5 arrives at the ear E8 at the time τ1.
. Direct sound D8 arrives after time τ2, and then at time τ. The reflected sound R8 arrives after a time τ. right ear E
The magnitude of each sound HR, D*, and Rm when reaching 7 is represented by the height of the graph in FIG. Further, from FIG. 1, the following relationship is derived.

However, C is the speed of sound. However, from these relationships in '), as shown by reference i - R in FIG. The reflected sound R8 can be canceled by emitting sound from the auxiliary speaker SPH so that the sound of the opposite phase reaches the auxiliary speaker SPH.

For this purpose, the acoustic signal given to the main speaker SPF is determined by the arrival time τ of the reflected sound R, and the arrival time τ of the auxiliary speaker SPH.
, and delay the arrival time τ1 of the sound from Multiplying the function 1・'G8, the electrical/acoustic conversion of the auxiliary speaker SPH and the auxiliary speaker S P
Transfer function G due to the acoustic path from H* to the right ear E,
By multiplying by the inverse function 11011 of l, the anti-phase sound −R,l can be given to the right ear E8.

FIG. 3 is a block diagram showing an electrical configuration related to the right ear E of the listener 12 of the sound reproduction device 11 according to an embodiment of the present invention. The acoustic signal from the acoustic signal 99.16 is given directly to the main speaker SPF from the power amplifier circuit 18, and is also given to the auxiliary speaker SPF from the power amplifier circuit 19 via the delay circuit A and the amplifier circuit B, and the delay circuit C and the amplifier circuit. is given to the speaker SPH. Delay circuit A, (
: J'J and amplifier circuits B and D constitute a correction circuit E.

The delay circuit A delays the acoustic signal by the difference τ2-τ between the arrival times of the direct sound and the reflected sound F, and the delay circuit A delays the acoustic signal by the time difference τ2−τ between the arrival time of the direct sound and the reflected sound F.
multiplies the electrical/'sound g conversion of the auxiliary speaker 5PH1l by the inverse function 17' GN of the transfer function GH by the acoustic path from the auxiliary speaker SPH* to the right ear E7.

The arrival time is thus delayed until the direct sound r)7, ka-)
The acoustic signal that has been corrected by the signal conversion and transmission path of the auxiliary speaker SPH* is delayed by the difference in arrival time τ−τ2 between the reflected sound R and the direct sound in the delay circuit C. given to the amplifier circuit.

In the amplifier circuit, the electrical/acoustic conversion of the main speaker S F' F and the reflection f from the main speaker SPF to the right ear E8
The transfer function 0 due to the g path is multiplied by the true inverse function 1/GR, and thus the sound -R8 of the opposite phase is radiated from the auxiliary speaker SPH,l.

The amplification circuits B and D are multiplied by coefficients -6g and G* as indicated by reference marks Ba and Da in the sound reproduction device 21 shown in FIG.
The same effect as the embodiment shown in I2I can be obtained.

On the other hand, in an actual car-mounted sound reproduction device, as shown in No. 50, main speakers 5PFL, 5PF1 . l is provided. Therefore, the right ear EIt of the listener 12 receives the direct sound D @, l and the reflected sound RR1l (hereinafter collectively referred to as P, l) from the right channel main speaker SPF, as well as the right channel main speaker SPF. Direct sound DRL and reflected sound R5 (hereinafter collectively referred to as Q) from 5PFL are incident. Similarly, the left ear EL has the right channel main speaker 5PF1. The direct sound, , * and the reflected sound R, , (hereinafter collectively referred to as P), the direct sound Dt, t, and the reflected sound RLL from the main speaker 5PFL of the left channel.
(Hereinafter, when generically referred to, it is represented by the reference mark QL) is incident. Car compartment 17 of a car as shown in Figure 5 of Manako
Since there are a plurality of reflected sounds R□, R: R@LI RLL, the sound reproducing device 31 used in such a vehicle interior 17 has a configuration as shown in, for example, No. 60.

That is, the right channel acoustic signal from the acoustic signal source 16 is transmitted to the power amplifier circuit 18 . The sound P11 is directly supplied to the right channel main speaker SPF via the power amplifier circuit 19, and the sound P11 is corrected by the corrector 28E1.
8 to the auxiliary speaker S P 11 ,
Further, the correction circuit E2 corrects the sound PL, and provides the sound PL to the auxiliary speaker 5PHL via the power amplification circuit 19L. Similarly, the left channel audio signal is transmitted through the power amplifier circuit 18L to the left channel main speaker 5PFL.
The correction circuit E3 provides the sound Q,
After the correction for l is performed, the power amplifier circuit 19. is applied to the auxiliary speaker SPH,l via the correction circuit E4.
The sound QL is corrected in the power amplifier circuit 19.
It is given to the auxiliary speaker 5PHL via L.

The correction circuit E1 calculates a delay time t equal to the difference in arrival time τ2−τ between the direct sound D from the right main speaker SPF and the direct sound H from the auxiliary speaker SPH.
a delay circuit A1 having a delay circuit A1, an electric/sound V conversion of an auxiliary speaker SPH, and a right ear E1. l
The inverse function of the transfer function GHR by the acoustic path up to 1/
Amplifier circuit B1 with G MR and 1 or I7&n
Said reflections @R, , -RR111, with a delay time t@,11~t□ equal to the arrival time difference τ, ~τ2 with the respective direct sound DLR. A delay circuit C1l having
= C1-, the electrical/single sound W conversion of the main speaker SPF, and the inverse function 1/G* of the transfer function G IINI-G true 1 due to the plurality of reflected acoustic paths from the main speaker SPF to the right ear E7 *+ to 1/Gll@7 amplifier circuits DII-D11, respectively. Therefore, from this correction circuit E1, a plurality of reflected sounds R,...
An output for canceling ~Roo is derived and given to the auxiliary speaker 5PHll.

The remaining correction circuits E2 to E4 are configured similarly to the correction circuit E1, and the correction circuit E2 is connected to the main speaker S of the right channel.
i a f > reflected sound Fj*p from PF to left ear EL,
+～n L l! An output for canceling the ++ is derived and given to the auxiliary speaker 5PHL. This corrector 28
The delay circuit A2 of E2 is the main speaker S on the right side and side.
Direct sound from P F6 r), and auxiliary speaker SPH,
, and the amplifier circuit B2 has a delay time t2 equal to the difference in arrival time with the direct sound HL from the auxiliary speaker SPH.
,, electric/i#W conversion and the auxiliary speaker S P Hc
, to the left ear E, , and the transfer function (3
It has an inverse function of 0, 1/GH, .

Also, from the correction circuit E3, the right channel main speaker 5P
Multiple reflected sounds Rt, L to RL from FL to left ear Et, /\
An output for canceling L+ is given to the auxiliary speaker SPHt. Furthermore, from the correction circuit 4, a plurality of reflected sounds R are transmitted from the right channel main speaker SPF to the right ear E8.
An output for canceling pt+~RRL, 11 is given to the auxiliary speaker 5PH1l. Delay circuit A of correction circuit E3
3 is direct sound D from the left channel main speaker 5PFL
It has a delay time t3 equal to the difference in arrival time between LL and the direct sound HL from the auxiliary speaker 5PHL, and the delay circuit A4 of the correction circuit E4 is connected to the main speaker 5 of the left channel.
Direct sound DRL from PFL and auxiliary speaker S F' H
It has a delay time t equal to the difference in arrival time with the direct sound H8 from R.

In this way, the present sound reproduction device 31 uses the correction circuits E1 to E4 corresponding to the reflected sounds R, , RL,; Sail; Acoustic output that cancels RLL + RRL is radiated from the auxiliary speakers 5PI-1, SPH, and these auxiliary speakers 5PHL
, SPH@ are provided near the listener 12, and therefore the listener 12 has this auxiliary speaker SPHL.

Since direct sounds HL and HRL from SPH* are not heard, the reflected sound R@RI RLll ; RLLI R
It is possible to perform sound field correction so that the position of the listener 12 becomes an optimal listening position by reducing the influence of IIL, and it is possible to perform sound reproduction with high fidelity.

Effects of the Invention As described above, according to the present invention, an auxiliary speaker is provided in the vicinity of the listening position, and the auxiliary speaker provides only direct sound to the listening position, and the auxiliary speaker emits sound that is the same as the reflected sound of the sound radiated from the main speaker. Since the sound that is out of phase at the level is radiated so that it matches the sound at the listening position, the reflected sound from the main speaker is canceled, and at the listening position, only the direct sound from the main speaker can be heard. Sound PJJ correction can be performed so that the position becomes the optimal listening position, and 9M reproduction with high fidelity can be performed.

[Brief explanation of the drawing]

FIG. 1 is a plan layout diagram showing the configuration of the sound reproducing device 11 according to an embodiment of the present invention, and FIG. A graph showing the relationship between τ and τ, FIG. 3 is a block diagram showing the electrical configuration of the sound reproduction device 7111, and No. 40 is a block diagram showing the electrical configuration of the sound reproduction device 21 of the embodiment of the present invention. 5 is a plan layout of a vehicle interior in which a sound reproducing device 31 according to a further embodiment of the present invention is used, FIG. 6 is a block diagram showing the electrical configuration of the sound reproducing device 31, and FIG. The figure is a plan view showing the relationship between direct sound and reflected sound R, Figure 8 is a graph showing the level difference and arrival time difference τ between direct sound and reflected sound R, and Figure 9 is a graph of a typical conventional technology. The block diagram showing the electrical configuration of the sound reproduction device 10, the 10th line is a graph showing problems caused by correction in the prior art. 11.21.31...Sound reproduction device, 12...Listener, 13...Wall surface, 14...Seat, 15...Headrest, 16...Acoustic signal source, 17...Car room, 1
8. ．． 18a; 19L, 19R...Power amplifier circuit, A, C...Delay circuit, B, D...Amplification circuit, E.
・・Correction circuit, SPF t,, SPF R...
Main speaker, 5PHL, SPH true... - Auxiliary speaker,
DRR, DLR: DIIL, DLL; H*HL・
・・Direct sound, Re* + RL, *: RRL I
RLt, - Reflected sound agent Patent attorney Kei Nishihara 111 Figure 2 Figure 2

Claims (1)

[Scope of Claims] A main speaker; an auxiliary speaker that provides only direct sound to the listening position; and an auxiliary speaker that transmits the acoustic signal given to the main speaker to the listening position by reflected sound of the sound emitted from the main speaker. a delay means for delaying by a difference τ_3 - τ_1 between a first propagation time τ3 required for the direct sound from the auxiliary speaker to propagate to the listening position and a second propagation time τ_1 required for the direct sound from the auxiliary speaker to propagate to the listening position; a first amplifier circuit having a first transfer function that is an inverse function 1/G_R of the transfer function G_R of the main speaker to the listening position of the reflected sound of the auxiliary speaker to the listening position of the direct sound from the auxiliary speaker; The second function is the inverse function 1/G_H of the transfer function G_H.
a second amplifier circuit having a transfer function, the delay means and the first and second amplifier circuits are connected in series to provide the acoustic signal to an auxiliary speaker. A sound reproduction device with.