JPH07336792A - On-vehicle sound field correction device - Google Patents

Abstract

PURPOSE:To obtain a desired characteristic of a long reverberation time with a small arithmetic operation quantity in a cabin. CONSTITUTION:A reverberation component is generated with reverberation generating means 11, 12 is generated by using a digital audio signal and added to the digital audio signal and the reverberation time in the cabin is prolonged up to the same degree of a reverberation time of a desired characteristic and a desired amplitude phase characteristic is obtained by FIR filters 3 to 6 for sound field correction. Thus, the desired characteristic of a long reverberation time with a few arithmetic operation quantity is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted sound field correction device used for correcting a sound field in a vehicle compartment to an appropriate sound field by using a digital filter.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a configuration of a conventional vehicle-mounted sound field correction apparatus, which shows a configuration when audio output is two channels. In FIG.
1, 2 are input terminals for digital audio signals, and 3 and 5
And 4 and 6 are FIR filters for sound field correction, which are connected to the digital audio input terminals 1 and 2, respectively. Reference numerals 7 and 8 denote adders, which are connected to the FIR filters 3 and 4 and 5 and 6 for correcting the sound field.
Digital audio output terminals 9 and 10 are connected to the adders 7 and 8.

Next, the conventional operation will be described. In FIG. 3, digital audio signals input from the digital audio input terminals 1 and 2 are converted into desired amplitude / phase characteristics by the sound field correction FIR filters 3 to 6. The outputs of the sound field correction FIR filters are added by adders 7 and 8 and output from digital audio output terminals 9 and 10.

The means for calculating the coefficients of the FIR filters 3 to 6 for sound field correction will be described below. The outputs of the digital audio output terminals 9 and 10 are D / A converted, amplified, and then radiated into the vehicle interior by the speaker. However, the output from the digital audio output terminals 9 and 10 in the vehicle interior to both ears of the listener is transmitted. The function matrix

[0005]

[Equation 1]

And the desired transfer function matrix is

[0007]

[Equation 2]

FIR filters 3 to 6 for correcting the sound field
The transfer function matrix of

[0009]

[Equation 3]

Then,

[0011]

Equation 4] With A = H ~ ¹ K, it is possible to the vehicle interior sound field to a desired sound field.

However, H ₁₁ is from the digital audio output terminal 9 to the listener's left ear, H ₂₁ is from the digital audio output terminal 9 to the listener's right ear, and H ₁₂ is from the digital audio output terminal 10 to the listener's left ear. H ₂₂ is each transfer function from the digital audio output terminal 10 to the listener's right ear, and K ₁₁ is a desired sound field, for example, from the L channel audio signal input at the center of two speakers in the listening room to the listener left. Up to the ear, K ₂₁ is from the L channel audio signal input to the listener's right ear, K ₁₂ is from the R channel audio signal input to the listener's left ear, K ₂₂
Is the transfer function from the R channel audio signal input to the listener's right ear, and the elements of each matrix are expressed in the frequency domain.

As described above, even in the above-described conventional vehicle-mounted sound field correction device, the sound field in the vehicle interior can be corrected to a desired sound field by appropriately selecting the transfer functions of the correction FIR filters 3 to 6. .

[0014]

However, while the reverberation time of the vehicle interior sound field is several tens of milliseconds, the reverberation time of the listening room is several hundreds of milliseconds, and the reverberation time of the concert hall is several seconds. In the above conventional vehicle-mounted sound field correction device, when correcting to a desired characteristic having a reverberation time approximately equal to the vehicle interior characteristic, the tap length of the sound field correction FIR filter is small, but the vehicle interior In order to realize a desired characteristic having a reverberation time longer than that of the characteristic, the tap length of the FIR filter for sound field correction needs to be increased, which causes a problem of enormous amount of calculation.

The present invention solves such a conventional problem, and an object of the present invention is to provide a vehicle-mounted sound field correction apparatus capable of realizing desired characteristics having a long reverberation time with a small amount of calculation. To do.

[0016]

In order to achieve the above object, the present invention further comprises reverberation component generating means for generating reverberation components on the output side or the input side of a sound field correction FIR filter, It is intended to lengthen the reverberation time of the characteristic.

[0017]

Therefore, according to the present invention, when a desired reverberation time is longer than that in the passenger compartment, it can be corrected by the FIR filter for correcting the sound field having a smaller tap length. Can be reduced.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the construction of a vehicle-mounted sound field correction apparatus according to an embodiment of the present invention. In FIG. 1, 11 and 12 are reverberation component generating means, which are connected to the adders 7 and 8. Reference numerals 13 and 14 denote adders, which are connected to the outputs of the reverberation component generating means 11 and 12 and the adders 7 and 8. In addition, the same reference numerals are given to the blocks having the same functions as those in FIG. 3, and the description thereof will be omitted.

Next, the operation of this embodiment will be described. In FIG. 1, digital audio signals input from the digital audio input terminals 1 and 2 are converted into desired amplitude / phase characteristics by the sound field correction FIR filters 3 to 6. The outputs of the FIR filters for sound field correction are added by adders 7 and 8, and reverberation component generating means 11 and 12 are generated.
And after the reverberation component is added by the adders 13 and 14,
Output from the digital audio output terminals 9 and 10.

The reverberation time in the passenger compartment is as short as several tens of milliseconds, while the reverberation time in the listening room is as long as several hundreds of milliseconds to several seconds. For example, if the reverberation time in the passenger compartment is 50 milliseconds and the desired characteristic is to be corrected to a characteristic having a reverberation time of 200 milliseconds, the difference between the desired characteristic and the reverberation time in the passenger compartment is 150
Although the millisecond is made by the FIR filter, since the FIR filter for correcting the sound field is not the feedback type, the tap length must be increased, which increases the amount of calculation. However, the reverberation component generation means 11 and 12 can increase the reverberation time in the vehicle compartment to a desired level.

FIG. 2 is a diagram showing an example of the configuration of the reverberation component generating means 11 and 12 of FIG. 1. In FIG. 2, 15 to 17 are multipliers, 19 and 20 are adders, and 21 is a delay device. The reverberation component generation means 11 and 12 are of a feedback type as shown in FIG. 2, and according to this, a long reverberation time can be created with a small amount of calculation.

As described above, according to the present embodiment, the difference in reverberation time between the vehicle interior characteristic and the desired characteristic is shortened, and the tap length of the sound field correction FIR filter can be reduced. The amount can be reduced.

[0023]

As described above, the in-vehicle sound field correction apparatus of the present invention is provided with the reverberation component generation means, so that the reverberation time of the vehicle interior characteristic is lengthened to a desired characteristic level and the desired amplitude F for sound field correction for phase characteristics
The tap length of the IR filter can be shortened, and the amount of calculation can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle-mounted sound field correction apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of reverberation component generation means in FIG.

FIG. 3 is a block diagram showing a configuration of a conventional vehicle-mounted sound field correction device.

[Explanation of symbols]

1, 2 ... Digital audio input terminals, 3-6 ... FIR filter for sound field correction, 7, 8, 13, 14, 19, 20
… Adder, 9, 10… Digital audio output terminal,
11, 12 ... Reverberation component generating means, 21 ... Delay device.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G10K 15/00 H03H 17/06 Z 8842-5J H04R 3/00 310 H04S 1/00 D

Claims (3)

[Claims] 1. An FIR filter for making a digital audio input signal a desired amplitude / phase characteristic, an adder for adding outputs of the FIR filter, and a reverberation component generation means for generating a reverberation component using the output of the adder as an input. And an adder for adding the adder output and the reverberation component generating means output. 2. The in-vehicle sound field correction device according to claim 1, wherein the reverberation component generating means has a characteristic having a reverberation time longer than that in the vehicle interior as a desired characteristic to be realized in the vehicle interior. . 3. The in-vehicle sound field correction device according to claim 1, wherein the reverberation component generating means is composed of a feedback filter.