JP3366447B2 - In-vehicle sound field correction device - Google Patents

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 when a sound field in a vehicle compartment is corrected to an optimum sound field using a digital filter.

[0002]

2. Description of the Related Art FIG. 5 shows the configuration of a conventional vehicle-mounted sound field correction device when the audio output is two channels of Lch and Rch. In FIG. 5, 501 and 502 are HP
F, 503, 504 are delay devices, 505, 506 are LPFs
(Low-pass filter), 507 and 508 are downsampling means, 509, 510, 511 and 512 are sound field correction FIR filters, 513 and 514 are adders, 51
5, 516 are upsampling means, 517, 518
Is an LPF, 519 and 520 are adders, 521 is a coefficient interchange unit, and 522 is a coefficient storage unit.

Next, the operation of the above conventional example will be described.
In FIG. 5, the Lch and Rch digital audio input signals are HPF 501, 502, and LP, respectively.
It is separated into high frequency components and low frequency components by F505 and 506. HPF 501, 502 and LPF
The cutoff frequencies of 505 and 506 are set between 500 Hz and 4 kHz so as to separate the localization of the sound image from the others. If you do not control the frequency above 500Hz, you will not be able to obtain a sufficient effect of improving the localization of the sound image.
If the above is controlled, the sound quality will deteriorate and the amount of calculation will increase due to the relationship with the wavelength.

The high frequency components separated by the HPFs 501 and 502 are delayed by the delays 503 and 504 by the delays generated by the sound field correction FIR filters 509 to 512, and are input to one of the adders 519 and 520. The low frequency components separated by the LPFs 505 and 506 are downsampling means 507 and 508.
Can lower the sampling frequency. LPF50
Reference numerals 5 and 506 also serve as filters for preventing aliasing. Here, the sampling frequency of the audio signal is converted by the sound field correction FIR filters 509 to 512.
This is to reduce the calculation amount of. The signal whose sampling frequency has been lowered is used for the sound field correction FIR filter 509.
The desired amplitude and phase characteristics are set by ˜512 and are input to the adders 513 and 514. Adders 513 and 51
4 output signals are up-sampling means 515, 51.
6, the sampling frequency is increased, passes through LPFs 517 and 518 for preventing aliasing, and the adder 51
It is the other input of 9,520. LPF517, 5
18 also has a role of interpolation processing of the up-sampled signal. The cutoff frequencies of the LPFs 517 and 518 are the same as those of the LPFs 505 and 506. The coefficient transposition device 521 includes a coefficient storage device 522 and a sound field correction FIR.
The filters of the sound field correction FIR filters 509 to 5 are connected to the filters 509 to 512, and the coefficients of the FIR filter are read from the coefficient storage 522 by the speaker opening angle control signal.
Swap the coefficients of 12. The speaker opening angle control signal is
For example, it is generated by the rotation of the speaker opening angle adjusting knob. The coefficient storage 522 stores the sound field correction FIR filter 50 for a plurality of desired characteristics having different speaker opening angles.
The coefficients 9 to 512 are stored.

FIG. 6 shows the structure of each FIR filter. In FIG. 6, 601 is a delay device, 602 is a multiplier, and 603 is an adder. The input signal to the FIR filter is delayed by one point by the delay device 601 and is multiplied by a constant by the coefficient of the multiplier 602. F
The output of the IR filter is the output of all the multipliers 602 added by the adder 603. This multiplier 6
By appropriately selecting the coefficient of 02, the input signal can be changed to a desired amplitude / phase characteristic.

FIG. 7 shows a sound field to be corrected, and FIG. 8 shows a desired sound field. In FIG. 7, 701 and 702 are A
/ D converters, 703 and 704 are D / A converters, 705,
Reference numeral 706 is an amplifier, 707 and 708 are speakers, 709 is a vehicle sound field correction device, 710 is a DHM (dummy head microphone), and 711 is a vehicle interior sound field. In FIG. 8, reference numerals 801 and 802 are amplifiers, 803 and 804 are speakers, and 805 DHM and 806 are desired sound fields such as a listening room sound field.

Next, a method of calculating coefficients of the sound field correction FIR filters 509 to 512 will be described with reference to FIGS. 7 and 8. In FIG. 7, an analog audio signal such as a CD player output signal is converted into a digital signal by A / D converters 701 and 702, and a vehicle sound field correction device 70 is installed.
It becomes 9 inputs. The output signal of the vehicle sound field correction apparatus 709 is converted from a digital signal to an analog signal by the D / A converters 703 and 704, and the amplifiers 705 and 706.
The signal radiated to the vehicle interior sound field 711, which is amplified by the speakers 707 and 708 and radiated to the vehicle interior sound field 711, has its amplitude and phase changed by the vehicle interior transfer function, and the DHM 710 (or the listener's Reach the binaural position, where the transfer function matrix from the D / A converters 703 and 704 inputs to the DHM710 binaural is

[Equation 1] And However, H ₁₁ is from the D / A converter 703 input to D
HM710 transfer function to the left ear, H ₂₁ is D / A converter 7
03 is a transfer function from the input to the right ear, H ₁₂ is a transfer function from the input of the D / A converter 704 to the left ear, and H ₂₂ is a transfer function from the input of the D / A converter 704 to the right ear. Also, the desired transfer function matrix is

[Equation 2] And K ₁₁ is an amplifier 80 in the desired sound field 806.
Transfer function from 1 input to DHM805 left ear, K ₂₁ is transfer function from amplifier 801 input to DHM805 right ear,
K ₁₂ is the transfer function from the amplifier 802 input to the DHM 805 left ear, and K ₂₂ is the transfer function from the amplifier 802 input to the DHM 805 right ear. The elements of each matrix are expressed in the frequency domain. The desired sound field 806 is, for example, a sound field symmetrical with respect to the DHM such as when the DHM is installed in the center of two speakers in the listening room. Here, the transfer function matrices of the sound field correction FIR filters 509 to 512 are set so that the output of the DHM 710 and the output of the DHM 805 become equal to each other.

[Equation 3]

[Equation 4] Thus, the vehicle interior sound field 711 can be corrected to a desired sound field 806.

As described above, even in the above-mentioned conventional vehicle sound field correction apparatus, if the opening angle of the speaker is changed as the desired sound field 806, for example, when the speaker opening angle adjusting knob is rotated. Since the coefficient interchanger 521 interchanges the coefficients of the sound field correction FIR filters 509 to 512, the opening angle of the speaker can be controlled.

[0009]

However, in the above-mentioned conventional vehicle-mounted sound field correction apparatus, a plurality of sound field correction FIR filter coefficients are required to continuously control the speaker opening angle, and many coefficients are required. There is a problem that the hardware scale becomes large because it is required to have a storage area.

SUMMARY OF THE INVENTION The present invention is intended to solve such a conventional problem, and an object thereof is to provide an excellent on-vehicle sound field correction device capable of controlling a speaker opening angle without requiring a large hardware scale. It is something.

[0011]

In order to achieve the above object, the present invention provides a first sound field correction for controlling a component that reaches a near ear from a desired speaker position at both listener's binaural positions. FIR filter and a second sound field correction FIR for controlling the component that reaches the opposite ear from the desired speaker position
A first sound field correction FIR filter including a filter
Amplitude frequency characteristic of the component controlled by the speaker and the amplitude frequency characteristic of the component controlled by the second sound field correction FIR filter, and the amplitude frequency reaching from the speaker to both ears by changing the level and delay. by changing the characteristics and time difference and the level difference is obtained by allowing controlling the opening angle of the speaker.

[0012]

Therefore, according to the present invention, the first sound field correction FIR filter controls the components from the desired speaker position to the near ear, and the second sound field correction FIR filter changes the desired speaker position from the desired speaker position. A component that controls the components up to the ear on the opposite side and is controlled by the first sound field correction FIR filter
The speaker opening angle can be continuously controlled by changing the amplitude frequency characteristic of the above and the amplitude frequency characteristic of the component controlled by the second sound field correction FIR filter, the level and the delay. Further, since there is no need for a coefficient storage, there is an effect that the hardware scale can be reduced. Furthermore, change the amplitude frequency characteristic by IIR
By using the filter, you can
That the speaker opening angle can be controlled accurately
Have an effect.

[0013]

【Example】

(Embodiment 1) FIG. 1 shows the configuration of the first embodiment of the present invention. In FIG. 1, 101 and 102 are HPFs,
103 and 104 are delay devices, 105 and 106 are LPFs, 1
07 and 108 are downsampling means, 109 and 11
0, 111, 112 are first sound field correction FIR filters, 113, 114, 115, 116 are second sound field correction FIR filters 117, 118, 119, 120,
121 and 122 are adders, 123 and 124 are upsampling means, and 125 and 126 are LPFs, 127 and 12.
8 is an adder, 129 and 130 are multipliers, 131 and 132
Is a delay device and 133 is a parameter changing device.

Next, the operation of the first embodiment will be described. In FIG. 1, the operation of correcting the vehicle interior sound field by the first sound field correction FIR filters 109 to 112 to a desired sound field is the same as that of the conventional vehicle-mounted sound field correction apparatus. However, the first sound field correction FIR filter 109-
112 controls only the components K ₁₁ and K ₂₂ to the ear closer to the desired speaker position in FIG. The second sound field correction FIR filters 113 to 116 control only the components K ₁₂ and K ₂₁ to the ear farther from the desired speaker position in FIG. Second sound field correction FIR filter 113
The input signals to 116 are downsampling means 10
The amplitudes of the outputs of 7 and 108 are changed by the multipliers 129 and 130, and delayed by the delay devices 131 and 132. The adders 121 and 122 include the first sound field correction F.
The output signals of the IR filters 109 to 112 and the output signals of the second sound field correction FIR filters 113 to 116 are added. The parameter changer 133 includes multipliers 129 and 13
0, the delay units 131 and 132 are connected to change the coefficients of the multipliers 129 and 130 and the delays of the delay units 131 and 132 according to the speaker opening angle control signal.

The distance from the speaker to the far ear and the near ear is determined from the model as shown in FIG. In FIG. 3, 301 is a speaker, 302 is a head, 303 is an ear position, 304 is a center of the head, r is a distance from the speaker 301 to the center of the head, ψ is a speaker opening angle, and D is an interaural distance. , Δs is the distance difference from the speaker 301 to both ears. In FIG. 3, if r is sufficiently larger than D / 2, the distance difference from the speaker 301 to both ears is Δs = D.
It is given by (ψ + sinψ) / 2. Speaker opening angle ψ
Changing this changes this distance, which changes the level and delay of the signal reaching both ears. The changes in the level and the delay are changed by the multipliers 129 and 130 and the delay devices 131 and 132. The amount of change in the level difference / delay difference may be pseudo-obtained from the model of FIG. 3, or the change formula is calculated from the experimental result of measuring the level / delay at the binaural position by changing the speaker opening angle ψ. Is also good.

As described above, according to the first embodiment,
By changing the levels and delays of the input signals to the second sound field correction FIR filters 113 to 116 by the multipliers 129 and 130 and the delay devices 131 and 132, the level difference and the time difference between the signals reaching the binaural positions. Can be changed. In addition, the coefficients of the multipliers 129 and 140 and the delays of the delay devices 131 and 132 are determined by the parameter changer 133.
The speaker opening angle can be continuously controlled, and the speaker opening angle can be continuously controlled.

(Embodiment 2) FIG. 2 shows the configuration of a second embodiment of the present invention. The embodiment of FIG. 2 is obtained by adding an IIR filter for changing the frequency characteristic of the input signal to the first embodiment. In FIG. 2, 201 and 202 are H
PF, 203 and 204 are delay devices, 205 and 206 are LP
F, 207 and 208 are downsampling means, 20
9, 210, 211 and 212 are FIRs for the first sound field correction
Filters 213, 214, 215 and 216 are second sound field correction FIR filters 217, 218, 219 and 2.
20, 221, 222 are adders, 223, 224 are upsampling means, 225, 226 are LPFs, 22
7, 228 are adders, 229 and 230 are multipliers, 23
1, 232 is a delay device, 233 is a parameter changer, and 23.
4, 235, 236 and 237 are IIR filters.

FIG. 4 shows the structure of the IIR filter. In FIG. 4, 401 is a delay device, 402 is a multiplier,
Reference numeral 403 is an adder.

Next, the operation of the second embodiment will be described. IIR filters 234, 235, 236, 237
Except for the portion, the same as in the first embodiment. When the speaker opening angle is changed, the level difference / time difference between both ears changes, and the amplitude frequency characteristics of the signals input to both ears also change. IIR filters 234, 235, 236, 23
Reference numeral 7 controls the variation of the amplitude frequency characteristic. The input signal to the IIR filter is the delay unit 4 on the input side.
The value is delayed by 01 by 1 point and is multiplied by a constant by the multiplier 402 on the input side. The output of the IIR filter is delayed by one point by the output delay device 401, and is multiplied by a constant by the output multiplier 402. The output signal of the IIR filter is the output of all the multipliers 402 added by the adder 403. The IIR filter cannot control the phase component, but by selecting the coefficient of the multiplier 402 appropriately, the FIR
The amplitude characteristic can be controlled with a smaller amount of calculation than the filter. Therefore, according to the second embodiment, the speaker opening angle can be controlled more accurately without increasing the calculation amount.

[0020]

As is apparent from the above-described embodiment, the present invention controls the components from the desired speaker position to the near ear by the first sound field correction FIR filter, and the second sound field correction FIR filter. The filter controls the component from the desired speaker position to the opposite ear , and the first sound field correction FIR filter is used.
Amplitude frequency characteristic of the component to be controlled by filter and amplitude frequency characteristics of the components controlled by the second sound field correction FIR filter
The speaker opening angle can be continuously controlled by changing the characteristics , level and delay. Also,
Small hardware scale because no coefficient store is required
It has the effect of being able to drill. In addition, the amplitude frequency characteristic
By changing the sex with an IIR filter,
Control speaker opening angle more accurately without increasing
It has the effect of being able to.

The present invention also includes a parameter modifier.
By changing the coefficient of the IIR filter, the coefficient of the multiplier, and the delay of the delay device, the amplitude frequency characteristic of the signal to the second sound field correction FIR filter, the input level, and the delay can be changed, and Since the amplitude frequency characteristic and the level difference / time difference can be changed, the speaker opening angle can be controlled.

[0022]

[0023]

[Brief description of drawings]

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

FIG. 2 is a schematic block diagram of a vehicle-mounted sound field correction apparatus according to a second embodiment of the present invention.

FIG. 3 is a model diagram of the difference in the reach from the speaker to both ears.

FIG. 4 is a block diagram of an IIR filter.

FIG. 5 is a schematic block diagram of a conventional vehicle-mounted sound field correction device.

FIG. 6 is an explanatory diagram of a sound field to be corrected

FIG. 7 Explanatory diagram of desired sound field

FIG. 8: FIR filter configuration diagram

[Explanation of symbols]

101, 102 HPF 103, 104 Delay device 105, 106 LPF 107, 108 Down-sampling means 109, 110, 111, 112 First sound field correction F
IR filters 113, 114, 115, 116 Second sound field correction F
IR filter 117, 118, 119, 120 Adder 121, 122 Multiplier 123, 124 Upsampling means 125, 126 LPF 127, 128 Adder 129, 130 Multiplier 131, 132 Delay device 133 Parameter changer 201, 201 HPF 203 , 204 Delayers 205, 206 LPFs 207, 208 Downsampling means 209, 210, 121, 212 First sound field correction F
IR filters 213, 214, 215, 216 Second sound field correction F
IR filter 217, 218, 219, 220 Adder 221, 222 Multiplier 223, 224 Upsampling means 225, 226 LPF 227, 228 Adder 229, 230 Multiplier 231, 232 Delay unit 233 Parameter changer 237 IIR filter

Claims (4)

(57) [Claims] 1. A first sound field correction FIR filter for controlling a component reaching a nearer ear from a desired speaker position at a listener's binaural position, and a farther ear from the desired speaker position. Second sound field correction FIR for controlling the component to be generated
And a filter for changing the amplitude frequency characteristic of the component controlled by the first sound field correction FIR filter and the amplitude frequency characteristic of the component controlled by the second sound field correction FIR filter, and the level and delay. A vehicle-mounted sound field correction device capable of controlling the opening angle of the speaker by changing the amplitude-frequency characteristic reaching the both ears from the speaker, the time difference, and the level difference. 2. The FIR filter for correcting the first sound field
Amplitude frequency characteristics of the controlled component and the second sound field correction
Change the amplitude frequency characteristic of the component controlled by the FIR filter.
The vehicle sound according to claim 1, further comprising an additional IIR filter.
Field correction device. 3. A multiplier for changing the level of the input signal to the second sound field correction FIR filter and a delay device to give a delay to the input signal to the second sound field correction FIR filter And a level of an input signal to the second sound field correction FIR filter and a delay thereof are changed.
2. The vehicle sound field correction device described in 2 . 4. A vehicle sound field correction apparatus of claim 3, further comprising a parameter change unit for changing the delay of the coefficient of the IIR filter coefficient of the multiplier the delayer.