JPH07184298A - On-vehicle sound field correction device - Google Patents

Abstract

PURPOSE:To provide the on-vehicle sound field correction device that is able to correct a sound field of a listener into an optimum sound field optimum to a seat position corresponding to a change in the seated position. CONSTITUTION:The device is provided with a correction FIR filter arithmetic section 12 correcting an amplitude 1 phase characteristic of a digital audio input signal, a filter coefficient storage section 17 storing plural kinds of filter coefficients of the correction FIR filter arithmetic section 12, a seat position discrimination means 15 discriminating a seated position, a filter coefficient selection means 14 selecting a filter coefficient of the kind corresponding to the discriminated seat position from the filter coefficient storage device, and a filter coefficient replacement device 16 replacing the filter coefficient of the correction FIR filter arithmetic section 12 with the selected filter coefficient to correct the sound field by replacing the filter coefficient of the correction FIR filter arithmetic section 12 with the filter coefficient corresponding to the discriminated seat position.

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 which is asymmetrical to a listener in a vehicle.

[0002]

2. Description of the Related Art Conventionally, there has been a device of this type as shown in FIG. FIG. 3 is a diagram showing a configuration of a conventional vehicle-mounted sound field correction device when the audio output is two channels. In FIG. 3, reference numeral 32 is an input terminal for inputting a digital audio signal, 31 is a correction FIR filter calculation unit for inputting a digital audio signal and corrects the sound field to the left and right, and 33 is a correction FIR filter calculation unit 31.
A correction FIR filter (e.g., delay unit in this figure (T _R, T _L) and a multiplier (C _R, consists C _L) and the like, these values determine the values of the filter coefficients), the The output is connected to the adder 34, and 35 is an output terminal for digital audio output which outputs the calculation result of the adder 34.

Next, the operation of the above conventional example will be described with reference to FIG. 3 again. In FIG. 3, the 2-channel digital audio signal input from the digital audio input terminal 32 is converted into a desired amplitude / phase characteristic by the correction FIR filter 33. The outputs of the correction FIR filter 33 are added by the adder 34 and output from the 2-channel digital audio output terminal 35 as a corrected digital audio output signal. As described above, in short, the conventional vehicle-mounted sound field correction device has the FI for correction.
It can be seen that the R filter calculation unit 31 is included.

Next, with reference to FIGS. 4 and 5, the details of the sound field correction using the conventional vehicle-mounted sound field correction device will be described. FIG. 4 is a diagram showing a state of sound field correction using a vehicle-mounted sound field correction device and a transfer function in a correction target sound field, and FIG. 5 shows a state of transfer function and sound field correction in a desired sound field. It is a figure. In FIG. 4, 41 is the same as in FIG.
A sound field correction device for vehicle as shown in FIG. 4, 42 D / A converter, 43 low pass filter (LPF), 44 amplifier, 45 speaker, 46 dummy head microphone, 47 sound field to be corrected in vehicle compartment Is. In FIG. 5, 51 is a D / A converter, 52 is an LPF, 53 is an amplifier, 54 is a speaker, 55 is a dummy head microphone, and 56 is a desired predetermined sound field.

Next, a specific method of correcting the sound field will be described with reference to FIGS. 4 and 5. The input 2-channel digital audio signal is applied to the vehicle-mounted sound field correction device 4
It is corrected by 1, output from there, converted into an analog signal by the D / A converter 42, passed through the LPF 43 for preventing aliasing, and then amplified by the amplifier 44,
Correction target sound field 4 as audio signals from the two speakers 45
7 is output. The audio signals output from the two speakers 45 have their amplitude and phase characteristics changed by the transfer function of the sound field 47 to be corrected, and reach the ears of a listener (dummy head microphone) 46.

Further, the transfer functions C _L , C _R , T _L and T _R of the correction FIR filter 33 are obtained as follows.
As shown in FIG. 4, the transfer function from the input of the D / A converter 42 to the output of the dummy head microphone 46 in the sound field 47 to be corrected is

[0007]

[Equation 1]

Then, the output of the dummy head microphone 46 placed in the sound field 47 to be corrected is

[0009]

[Equation 2]

Then, the transfer function of the on-vehicle sound field correction device 41 is

[0011]

[Equation 3]

[0012] Further, the transfer function from the input of the D / A converter 51 placed in the desired sound field 56 shown in FIG. 5 to the output of the dummy head microphone 55 is

[0013]

[Equation 4]

The output of the dummy head microphone 55 placed in the desired sound field 56 is

[0015]

[Equation 5]

And the input signal is

[0017]

[Equation 6]

Then, the transfer function of the on-vehicle sound field correction device 41 is

[0019]

[Equation 7]

As a result, the transfer function of the sound field 47 to be corrected including the on-vehicle sound field correction device 41 is

[0021]

[Equation 8]

And the transfer function of the desired sound field 56 (equation 4) is satisfied. However, the elements of each matrix are expressed in the frequency domain.

As described above, also in the above-described conventional vehicle-mounted sound field correction apparatus, the transfer function of the correction FIR filter is appropriately selected so that the sound field to be corrected has the desired sound at the positions of both ears of the listener. Can be corrected in place.

[0024]

However, in the above-mentioned conventional vehicle sound field correction apparatus, since the coefficient of the correction FIR filter 33 is fixed, the listening position changes, for example, the seat moves in the front-back direction. In such a case, when the vehicle interior characteristic changes, there is a problem that the desired sound field cannot be corrected correspondingly.

The present invention has been made in view of such a conventional problem, and is capable of correcting the sound field to be corrected to a desired sound field in response to changes in vehicle interior characteristics such as seat position. An object is to provide a sound field correction device.

[0026]

In order to achieve the above-mentioned object, a vehicle-mounted sound field correction apparatus according to the present invention has a correction F for correcting the amplitude / phase characteristics of a digital audio input signal.
An IR filter calculation unit, a filter coefficient storage unit that stores a plurality of types of filter coefficients of the correction FIR filter calculation unit, a seat position determination unit that determines a seat position, and a type of filter that corresponds to the determined seat position. The correction FIR includes a filter coefficient selection unit that selects a coefficient from the filter coefficients stored in the filter coefficient storage unit, and a filter coefficient replacement unit that replaces the filter coefficient of the correction FIR filter operation unit with the selected filter coefficient. The sound field is corrected by replacing the filter coefficient of the filter calculation unit with the filter coefficient corresponding to the determined seat position.

Further, in order to achieve the above object, the on-vehicle sound field correction device according to the present invention corrects the amplitude / phase characteristics of the digital audio input signal, and the correction FIR filter calculation unit. , A filter coefficient storage unit that stores a plurality of types of filter coefficients, a seat position selection switch that selects a position corresponding to the changed seat position and outputs a signal indicating the position, and a seat position selection switch that corresponds to the selected position. A filter coefficient selecting unit for selecting a filter coefficient from the filter coefficients stored in the filter coefficient storage unit; and a filter coefficient replacing unit for replacing the filter coefficient of the correction FIR filter operation unit with the selected filter coefficient, Replace the filter coefficient of the correction FIR filter calculation unit with the filter coefficient corresponding to the changed seat position. And correcting the sound field.

[0028]

The present invention is configured as described above, and in particular, the seat position is determined by the seat position determination means or the seat position is selected by the seat position selection switch, and stored in the filter coefficient storage based on the output signal. By changing the filter coefficient of the type selected from the plurality of types of filter coefficients that have been selected, through the filter coefficient transposition device, with the filter coefficient of the correction FIR filter operation unit, the sound field to be corrected changes in seat position. Accordingly, it is possible to correct the desired sound field in the passenger compartment.

[0029]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a vehicle-mounted sound field correction apparatus according to the first embodiment of the present invention. In FIG. 1, 11 is a digital audio signal input terminal, 1
Reference numeral 2 is a correction FIR filter operation unit that is connected to the digital audio signal input terminal 11 and receives the digital audio signal to correct the sound field. Reference numeral 13 is a digital audio signal that outputs the digital audio signal corrected by the correction FIR filter operation unit 12. It is an output terminal. The internal structure of the correction FIR filter calculation unit 12 is the same as that of the conventional correction FIR filter calculation unit 31 shown in FIG.

Further, 14 is a correction F based on the position of the seat.
Filter coefficient selecting means for selecting the filter coefficient of the IR filter, 15 is a seat position determining means for determining the position of the seat in the sound field to be corrected and notifying the result to the filter coefficient selecting means 14, 16 is a correction FIR filter calculation Part 1
A filter coefficient transposition device that transposes the coefficient of No. 2 with the filter coefficient stored in the filter coefficient storage device, and 17 stores a plurality of types of filter coefficients supplied to the correction FIR filter operation unit 12 via the filter coefficient transposition device 16. It is a filter coefficient storage.

Next, the operation of the first embodiment will be described with reference to FIG. In the first embodiment, the digital audio signal input to the digital audio signal input terminal 11 is input to the correction FIR filter operation unit 12. The digital audio signal input to the correction FIR filter operation unit 12 is converted into a desired amplitude / phase, and the digital audio signal output terminal 13
Is output from.

On the other hand, the seat position determining means 15 automatically determines the position of the seat in the front-rear direction and outputs the information signal. The filter coefficient selection means 14 is based on the output signal of the seat position determination means 15 and the filter coefficient storage 1
One of the filter coefficients stored in 7 is selected and the filter coefficient interchanger 16 is notified. According to the notification from the filter coefficient selecting means 14, the filter coefficient transposing unit 16 selects a filter coefficient of a type corresponding to the filter coefficient stored in the filter coefficient storage unit 17, and a correction FIR filter operation unit. feed 12, the filter coefficients (e.g., T _R of FIG. 3, T _L, C
_R, replaced with C _L, such as), or to change.

Therefore, for example, in the case where the seat position determining means 15 has a structure in which the seat moves back and forth on the rail, the seat position can be easily determined by determining which position the seat is on the rail. It can be configured to determine. The seat position determining means 15 may be a means for directly determining the seat position in addition to the position determination by the rail of the seat, and the determining means uses an electric member such as a photodiode or a mechanical member such as a switch. It may be constituted by any electrical, mechanical or other combination means, such as

As described above, according to the first embodiment of the present invention, when the seat position is changed in the front-rear direction, the filter coefficient of the correction FIR filter calculation unit 12 is automatically set corresponding to the seat position. By changing the positions, the sound field in the vehicle interior can be corrected according to the change in the seat position.

Next, the second embodiment of the present invention will be described in detail with reference to FIG. FIG. 2 is a block diagram showing the configuration of a vehicle-mounted sound field correction apparatus according to the second embodiment of the present invention. In the second embodiment, the seat position determination means 15 of the first embodiment is replaced with a seat position selection switch 25.
When the passenger moves the seat back and forth, the seat position selection switch 25 selects a position or an output corresponding to the seat position and sends it to the filter coefficient selecting means 14, and the filter coefficient interchanger 16 causes the filter coefficient to be changed. In the same way as in the first embodiment, the vehicle interior sound field can be corrected so that an optimal sound field can be configured according to the change in seat position, and the listener can judge the sound field by himself / herself. Can be corrected to obtain the optimum sound field.

That is, the seat position selection switch 25 is used for correction FIR so that the listener can obtain the optimum sound field by his / her own judgment.
It is a switch for selecting the filter coefficient of the filter, and may be configured by any electrical, mechanical, or combination switch thereof such as a slide, a push button, a rotary switch, or a remote. In the second embodiment,
Since the parts other than the seat position selection switch 25 are the same as those in the first embodiment, further description will be omitted.

[0037]

As is apparent from the above description, according to the present invention, the filter coefficient of the correction FIR filter is exchanged according to the change of the seat position, so that the vehicle interior characteristic due to the change of the seat position is improved. Even if there is a change, it is possible to correct the optimum desired vehicle interior sound field according to the seat position.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a configuration of an in-vehicle sound field correction device according to a second embodiment of the present invention.

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

FIG. 4 is a diagram showing a transfer function in a sound field to be corrected and a state of sound field correction using an in-vehicle sound field correction device.

FIG. 5 is a diagram showing a transfer function and a sound field correction state in a desired sound field.

[Explanation of symbols]

 11 Digital Audio Signal Input Terminal 12 Correction FIR Filter Calculation Unit 13 Digital Audio Signal Output Terminal 14 Filter Coefficient Selection Means 15 Seat Position Determining Means 16 Filter Coefficient Exchanger 17 Filter Coefficient Storage 25 Seat Position Selection Switch 31 Correction FIR Filter Calculation Part 32 Digital audio signal input terminal 33 Correction FIR filter 34 Adder 35 Digital audio signal output terminal 41 In-vehicle sound field correction device 42, 51 D / A converter 43, 52 LPF 44, 53 Amplifier 45, 54 Speaker 46, 55 Dummy head microphone 47 Sound field to be corrected 56 Desired sound field

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04R 3/04 5/02 F

Claims (2)

[Claims] 1. A correction FIR filter operation unit for correcting the amplitude / phase characteristics of a digital audio input signal, a filter coefficient storage unit for storing a plurality of types of filter coefficients of the correction FIR filter operation unit, and a seat position. And a filter coefficient selecting means for selecting a filter coefficient of a type corresponding to the determined seat position from the filter coefficients stored in the filter coefficient storage, and the correction FIR filter operation. And a filter coefficient interchanger for exchanging a filter coefficient of a section with the selected filter coefficient, and the sound field is corrected by replacing the filter coefficient of the correction FIR filter operation section with the filter coefficient corresponding to the determined seat position. An in-vehicle sound field correction device characterized by: 2. A correction FIR filter calculation unit for correcting the amplitude / phase characteristics of a digital audio input signal, a filter coefficient storage unit for storing a plurality of types of filter coefficients of the correction FIR filter calculation unit, and a changed seat. A seat position selection switch for selecting a position corresponding to the position and outputting a signal indicating the position, and a filter coefficient selecting unit for selecting a filter coefficient of a type corresponding to the selected position from the filter coefficient storage, A filter coefficient interchanger for exchanging the filter coefficient of the correction FIR filter operation unit with the selected filter coefficient is provided, and the filter coefficient of the correction FIR filter operation unit is exchanged with the filter coefficient corresponding to the changed seat position. An in-vehicle sound field correction device characterized by correcting a sound field.