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JPH07184298

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DESCRIPTION JPH07184298
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
on-vehicle sound field correction apparatus used to correct an asymmetrical sound field for a
listener in a vehicle compartment.
[0002]
2. Description of the Related Art Heretofore, an apparatus of this type has been shown in FIG.
FIG. 3 is a view showing the configuration of a conventional in-vehicle sound field correction
apparatus in the case where two channels of audio output are provided. In FIG. 3, 32 is an input
terminal for inputting a digital audio signal, 31 is a correction FIR filter operation unit for
inputting a digital audio signal to correct the sound field to the left and right, 33 is a correction
of the correction FIR filter operation unit 31 FIR filter (for example, in this figure, consisting of a
delay (TR, TL) and a multiplier (CR, CL) etc., the values of which determine the value of the filter
coefficient), and the output thereof is Reference numeral 35 denotes an output terminal for
digital audio output which outputs the calculation result of the adder 34.
[0003]
Next, the operation of the conventional example will be described with reference to FIG. 3 again.
In FIG. 3, the digital audio signal of two channels input from the digital audio input terminal 32 is
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converted by the correction FIR filter 33 into a desired amplitude / phase characteristic. The
output of the correction FIR filter 33 is added by the adder 34 and output from the digital audio
output terminal 35 of two channels as a corrected digital audio output signal. As described
above, it can be seen that the conventional on-vehicle sound field correction apparatus comprises
the correction FIR filter operation unit 31.
[0004]
Next, with reference to FIGS. 4 and 5, the details of the sound field correction using the abovedescribed conventional on-vehicle sound field correction apparatus will be described. FIG. 4 is a
view showing a state of sound field correction using the on-vehicle sound field correction
apparatus and a transfer function in the sound field to be corrected, and FIG. 5 is a view showing
a transfer function and sound field correction in a desired sound field. FIG. In FIG. 4, 41 is an onvehicle sound field correction apparatus as shown in FIG. 3, 42 is a D / A converter, 43 is a low
pass filter (LPF), 44 is an amplifier, 45 is a speaker, 46 is a dummy head microphone , 47 are
correction target sound fields in the vehicle compartment. Further, 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.
[0005]
Next, a specific method of sound field correction will be described with reference to FIGS. 4 and
5. The two-channel digital audio signal that has been input is corrected by the on-vehicle sound
field correction device 41, output therefrom, converted to an analog signal by the D / A converter
42, passed through the LPF 43 for aliasing prevention, and then amplified. The signal is
amplified at 44 and output from the two speakers 45 as an audio signal to the sound field 47 to
be corrected. The sound signal output from the two speakers 45 has its amplitude and phase
characteristics changed by the transfer function of the sound field 47 to be corrected, and
reaches the ear of the listener (dummy head microphone) 46.
[0006]
Further, transfer functions CL, CR, TL, and TR 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 correction target sound field 47 is
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[0008]
Assuming that the output of the dummy head microphone 46 placed in the sound field 47 to be
corrected is
[0010]
Assuming that the transfer function of the in-vehicle sound field correction device 41 is
[0012]
【0012】とする。
Also, 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
[0014]
Let the output of the dummy head microphone 55 placed in the desired sound field 56 be
[0016]
Let the input signal be
[0018]
Assuming that the transfer function of the on-vehicle sound field correction device 41 is
[0020]
The transfer function including the vehicle-mounted sound field correction device 41 in the
correction target sound field 47 is
[0022]
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And agrees with the transfer function (Equation 4) of the desired sound field 56.
However, the elements of each matrix are expressions in the frequency domain.
[0023]
As described above, even in the above-described conventional on-vehicle sound field correction
apparatus, the sound field to be corrected is corrected to the desired sound field at the position
of the listener's both ears by appropriately selecting the transfer function of the correction FIR
filter. can do.
[0024]
However, in the above-described conventional sound field correction apparatus for vehicle, since
the coefficient of the correction FIR filter 33 is fixed, the change of the listening position, for
example, the seat is moved in the front and back direction In such a case, when the vehicle
interior characteristics change, there is a problem that the sound field can not be corrected to the
desired sound field.
[0025]
The present invention has been made in view of such conventional problems, and it is possible to
correct the sound field to be corrected to a desired sound field in response to the change in the
vehicle interior characteristics such as the seat position. It aims at providing a correction device.
[0026]
SUMMARY OF THE INVENTION In order to achieve the above object, according to the present
invention, there is provided a correction FIR filter operation unit for correcting the amplitude and
phase characteristics of a digital audio input signal, and Filter coefficient storage for storing a
plurality of types of filter coefficients of the FIR filter operation unit, seat position determination
means for determining the position of a seat, and filter coefficients for the type corresponding to
the determined seat position are stored in the filter coefficient storage Filter coefficient selection
means for selecting from the filter coefficients being selected, and a filter coefficient exchange
unit for replacing the filter coefficients of the correction FIR filter operation unit with the
selected filter coefficients, wherein the filter coefficients of the correction FIR filter operation unit
The sound field is corrected by replacing the filter coefficient corresponding to the determined
seat position.
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[0027]
Furthermore, in order to achieve the above object, the vehicle-mounted sound field correction
device according to the present invention includes a plurality of types of correction FIR filter
operation units that correct the amplitude and phase characteristics of the digital audio input
signal and a plurality of correction FIR filter operation units. Filter coefficient storage for storing
the filter coefficients, a seat position selection switch for selecting a position corresponding to
the changed seat position and outputting a signal indicating the position, and a type of filter
coefficient corresponding to the selected position Filter coefficient selection means for selecting
from the filter coefficients stored in the filter coefficient storage unit; and a filter coefficient
exchange unit for replacing the filter coefficients of the correction FIR filter operation unit with
the selected filter coefficients; Correct the sound field by replacing the filter coefficient of the
filter operation unit with the filter coefficient corresponding to the changed seat position And
wherein the Rukoto.
[0028]
According to the present invention, 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 replacing the filter
coefficients of the selected type from the plurality of filter coefficients being replaced with the
filter coefficients of the correction FIR filter operation unit via the filter coefficient interchanger,
the change of the sound field to be corrected changes in the seat position Thus, it is possible to
correct to the desired sound field in the vehicle interior that is optimum for the
[0029]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be
described in detail with reference to the attached drawings.
FIG. 1 is a block diagram showing the configuration of a sound field correction apparatus for a
vehicle according to a first embodiment of the present invention.
In FIG. 1, 11 is a digital audio signal input terminal, 12 is a digital signal input terminal 11,
receives a digital audio signal, and a correction FIR filter operation unit for correcting a sound
field; 13 is a correction FIR filter operation unit 12 It is a digital audio signal output terminal for
outputting a digital audio signal corrected by the above.
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The internal configuration of the correction FIR filter operation unit 12 is the same as that of the
conventional correction FIR filter operation unit 31 shown in FIG.
[0030]
Further, 14 is a filter coefficient selection means for selecting the filter coefficient of the FIR filter
for correction based on the position of the seat, and 15 is a seat for determining the position of
the seat in the sound field to be corrected and notifying the filter coefficient selection means 14
of the result. Position determining means, 16 is a filter coefficient changer that replaces the
coefficient of the correction FIR filter operation unit 12 with the filter coefficient stored in the
filter coefficient storage, and 17 is a correction FIR filter operation unit via the filter coefficient
exchange 16 12 is a filter coefficient storage unit for storing a plurality of types of filter
coefficients to be supplied to 12;
[0031]
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 to a
desired amplitude and phase, and is output from the digital audio signal output terminal 13.
[0032]
On the other hand, the seat position determination means 15 automatically determines which
position in the front-rear direction the seat is in, and outputs the information signal.
The filter coefficient selection unit 14 selects one of the filter coefficients stored in the filter
coefficient storage unit 17 based on the output signal of the seat position determination unit 15
and notifies the filter coefficient replacement unit 16 of it.
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The filter coefficient replacing unit 16 selects a filter coefficient of a type corresponding to the
filter coefficients stored in the filter coefficient storage unit 17 according to the notification from
the filter coefficient selection unit 14, and a correction FIR filter operation unit 12 and replace or
change with the filter coefficients (e.g., TR, TL, CR, CL in FIG. 3).
[0033]
Therefore, for example, in the case of a structure in which the seat moves back and forth on the
rail, the seat position determination means 15 can easily determine the seat position by
determining which position on the rail the seat is on. It can be configured.
The seat position determination means 15 may directly determine the seat position in addition to
the position determination using the rails of the seat, and the determination means may use an
electrical member such as a photodiode or a mechanical member such as a switch It may be
configured by any electrical, mechanical or other combination means, such as
[0034]
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 coefficients of the correction FIR filter
calculation unit 12 are automatically replaced in correspondence with the seat position. By doing
this, it is possible to correct the in-room sound field according to the change of the seat position.
[0035]
Next, with reference to FIG. 2, a second embodiment of the present invention will be described in
detail.
FIG. 2 is a block diagram showing the configuration of a sound field correction apparatus for a
vehicle according to a 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.
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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
selection means 14, and the filter coefficient replacing unit 16 As in the first embodiment, it is
possible to perform in-vehicle sound field correction so as to construct an optimum sound field
according to a change in the seat position, as well as in the first embodiment. Correction to
obtain an optimal sound field.
[0036]
That is, the seat position selection switch 25 is a switch for selecting the filter coefficient of the
FIR filter for correction so that the listener obtains the optimum sound field at his own judgment,
and any electric such as a slide, a push button, a rotary switch or a remote It may be configured
by a mechanical, mechanical or combination thereof.
In the second embodiment, parts other than the seat position selection switch 25 are the same as
those of the first embodiment, and thus 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 replaced in response 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 it changes, it is possible to correct it to an optimal desired in-vehicle sound field according to
the seat position.
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