JP2000197182A - Loudness control method and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient loudness adjustment quantity. SOLUTION: A band split section 12 divides a sound signal of each channel selected by an input selector section 11, a level control section 13 changes a sound volume of each divided band in following to an entire sound volume change by a main volume 17 and a mix circuit 15 synthesizes a sound signal of one channel. Furthermore, an optimum sound system is built up by interlocking sound quality control, balance control and fader control with the entire sound volume change. Thus, while sufficiently ensuring the loudness adjustment quantity, the sound quality and the sound image localization are controlled and the listening sensitivity can be corrected in addition to a special reproduction condition required for an on-vehicle application or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling loudness in audio equipment such as on-vehicle equipment, home equipment, and portable equipment.

[0002]

2. Description of the Related Art A conventional acoustic device is configured such that a capacitor and a resistor are simply connected to a part of a volume controller, and bass and treble are changed according to the volume by using the filter characteristics. In most cases, the volume adjuster had little effect at an adjustment position above a certain volume, and at the adjustment position below a certain volume, the frequency characteristics of the same pattern generally moved in parallel according to the volume. .

[0003]

However, in the above-mentioned conventional method, only an adjustment amount of about +6 to 12 dB can be obtained, and a case where an adjustment amount larger than this is required or a sound quality as a loudness characteristic is desired to be sufficiently obtained. The case was not fully answered. In the case of an in-vehicle device,
In the conventional loudness control of only two channels, the diameter of the speaker is often limited due to the restriction of the mounting position, and the usual listening point is almost always not equidistant from the speaker, and the left and right at the listening point Even if the front and rear speakers had the same loudness characteristics, the effect of the loudness characteristics was not sufficient due to the difference in distance from each speaker. In addition, since there may be four or more sound sources having different reproduction bands, such as radio, television, tape, and CD, there is a problem that it is difficult to correct the perceptual sensitivity including consideration of sound image localization, phase, and sound quality. Was. In particular, when the bass is emphasized by the loudness control, the loudspeaker is often set at a low position, and the sound image is reduced. Further, there is a problem that the roundness effect when a multi-speaker system or a multi-amplifier system is adopted is not so different from that of a two-channel system.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a loudness control method and a loudness control device capable of obtaining a loudness characteristic sufficiently effectively.

[0005]

According to the present invention, in order to achieve the above object, the audio signal of each channel is divided into bands, and the loudness of each divided band is made to follow a change in loudness. The sound quality, balance control, and fader control are also linked to the overall volume change to create an optimal sound system. As a result, sound quality and sound image localization can be controlled while ensuring a sufficient variable amount, and audibility sensitivity correction can be performed in consideration of special reproduction conditions for in-vehicle use and the like.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a frequency is divided into bands in order to correct the audibility of an input audio signal, and the volume of each of the divided frequencies is calculated as follows.
This is a loudness control method that changes the volume of the audio signal output following the overall volume change.In the past, the loudness effect was limited, but the volume was adjusted for each band. The loudness effect can be provided up to the adjustment range of

According to a second aspect of the present invention, there is provided the loudness control method according to the first aspect, wherein the cutoff frequency of each frequency is changed in accordance with a change in the whole volume when the frequency band is divided. By changing the cutoff frequency according to the level of the band, there is an effect that the connection between the divided bands can be improved.

According to a third aspect of the present invention, there is provided the loudness control method according to the first aspect, wherein a cutoff characteristic of each frequency is switched in a plurality of stages during band division. It has the effect that characteristics can be selected.

According to a fourth aspect of the present invention, an audio signal for each frequency, which is divided into bands and whose volume is adjusted, is extracted and output from an independent power amplifier and a speaker. This is a loudness control method, and has an effect that an optimum loudness characteristic at a listening point can be obtained.

According to a fifth aspect of the present invention, the position of the sound image is changed by changing a specific frequency region among the band-divided frequencies following a change in the overall volume. A loudness control method according to claim 1, which has an effect of improving the position of a sound image in an in-vehicle acoustic system in which a speaker arrangement is particularly restricted.

According to a sixth aspect of the present invention, in a sound system having speakers arranged in front, rear, left and right, a balance control and a fader control are interlocked according to a change in the whole volume, and a listening point of a viewer is provided. The loudness control method according to claim 1, wherein the loudness control method has an effect of improving a stereo feeling in an in-vehicle acoustic system in which the position of a viewer is not located at the center of the left, right, front and rear speakers.

According to a seventh aspect of the present invention, in a vehicle-mounted audio system, when a voice guide signal of another device is input during output of a voice signal, a frequency-divided middle-range voice signal is output. The loudness control method according to claim 1, wherein the level is attenuated and the level of the voice guidance signal is increased, and the clarity of the guidance voice signal is improved while maintaining an optimum loudness characteristic even when the voice guidance signal is input. It has the effect that it can be done.

According to an eighth aspect of the present invention, there is provided a means for band-dividing a frequency for correcting audibility, and a step of changing a sound volume of each band-divided frequency to a sound volume change of an entire audio signal output. The loudness control device comprises means for changing the loudness effect.The loudness effect is conventionally limited, but the volume is adjusted for each band, so that the loudness effect is theoretically provided up to the adjustment range of the main volume. It has the effect of being able to.

According to a ninth aspect of the present invention, there is provided the loudness control apparatus according to the eighth aspect, further comprising means for changing a cutoff frequency of each frequency at the time of band division by following a change in the overall volume. By changing the cutoff frequency according to the level of each band, there is an effect that the connection between the divided bands can be improved.

According to a tenth aspect of the present invention, there is provided the loudness control apparatus according to the eighth aspect, further comprising means for switching a cutoff characteristic of each frequency to a plurality of stages during band division. This has the effect that the loudness characteristic can be selected.

According to the eleventh aspect of the present invention, there is provided a loudness control apparatus according to the eighth aspect, further comprising means for extracting an audio signal for each frequency divided into bands and outputting the audio signal from an independent power amplifier and a speaker. This has the effect that an optimum loudness characteristic at the listening point can be obtained.

The invention according to a twelfth aspect of the present invention is provided with means for changing the sound volume of a specific frequency region among the band-divided frequencies by following a change in the whole sound volume.
The loudness control device described above has an effect of improving a position of a sound image in an in-vehicle acoustic system in which a speaker arrangement is particularly restricted.

According to a thirteenth aspect of the present invention, in an audio system having speakers at front, rear, left and right, a balance control and a fader control are interlocked in accordance with a change in overall sound volume, so that a viewer can listen at a listening point. 9. The loudness control device according to claim 8, further comprising an optimizing means, and particularly has an effect of improving a stereo feeling in an in-vehicle acoustic system in which the position of a viewer is not located at the center of left, right, front and rear speakers.

According to a fourteenth aspect of the present invention, in the on-vehicle acoustic system, there is provided means for mixing a voice signal and a voice guide signal of another device, and the voice of another device is output during the output of the voice signal. 9. The loudness control device according to claim 8, further comprising means for, when a guidance signal is input, attenuating the level of the frequency-divided mid-range audio signal and increasing the level of the audio guidance signal. This also has the effect of improving the clarity of the guidance voice signal while maintaining the optimum loudness characteristics even when the voice guidance signal is input.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) First, an overall loudness control method and apparatus according to the present invention will be described with reference to FIG. In FIG. 1, reference numeral 11 denotes an input selector for switching an input source of an audio signal.
Assuming a tape, radio, and the like, a case is shown in which only the left channel is input. As a whole, this control block is provided for 4 channels or 6 channels. 12
Is a band dividing unit that performs band division of the input audio frequency, and here, it is divided into three parts, a low band, a middle band, and a high band. Reference numeral 13 denotes a level control unit that changes the sound volume of each of the band-divided frequencies in accordance with the sound volume change of the main volume 17, and is configured by a VCA (Voltage Controlled Amplifier) having an attenuation characteristic as shown in FIG. . Reference numeral 14 denotes a buffer for each frequency whose level has been adjusted, and reference numeral 15 denotes a mix circuit that mixes the output of each buffer 14 and synthesizes it into a one-channel signal (here, the left channel). Reference numeral 16 denotes a level control unit for inputting a voice guidance signal for navigation and setting an optimum mixing level following a change in the volume of the main volume 17.
It is composed of CA. Reference numeral 17 denotes a main volume for adjusting the volume of the entire input audio signal. As shown in FIG. 2, the control voltage V controls the amount of attenuation of each VCA. Reference numeral 18 denotes a multi-amplifier output terminal for independently controlling the output of the control level unit 13 by an external multi-amplifier. Note that the band division unit 1
2 and the level control unit 13 include a DSP (Digita
l Signal Processor) 19.

Next, the operation of the above embodiment will be described. When a sound source is selected by the input selector section 11, the frequency of the audio signal is divided into three parts of a low band, a middle band and a high band by the band dividing section 12, and the level of the main volume 17 is changed by the level control section 13, respectively. It is variable according to the quantity. Each VCA in the level control unit 13
2, the attenuation increases as the control voltage V of the main volume 17 increases, but the attenuation is controlled so that the attenuation differs depending on the band. As a result, necessary loudness characteristics as shown in 20 can be obtained. Here, the loudness effect can be further enhanced by adjusting the adjustment by the main volume 17 so that the auditory sensitivity can be linearly changed in, for example, ± 2 dB steps.

(Embodiment 2) FIG. 3 shows another configuration of the band division unit 12 and the level control unit 13 in the roundness control device of the present invention. Band division unit 1
2 and the level control unit 13 are provided with VCAs, and the variable resistors VR1 to VR11 in each VCA are provided.
Changes the attenuation amount according to the control voltage V from the main volume 17. By using the variable resistor VR for the resistance portion of the filter in the band dividing section 12 and changing the cutoff frequency of each frequency following the change in the whole volume by the main volume 17 at the time of band division, volume control in each band is performed. In addition, a smooth loudness characteristic can be created by simultaneously controlling the crossover frequency between the bands. FIG. 4A shows a case where only the level adjustment of each band is performed, and FIG. 4B shows a characteristic when the cutoff frequency is varied according to the level of each band, and adjusts the crossover frequency. By doing so, it is shown that the loudness characteristics can be made smooth.

(Embodiment 3) FIG. 5 shows still another configuration of the band division unit and the level control unit in the roundness control device of the present invention. FIG. 5 shows only the low-frequency portion, but the same configuration is provided in the middle and high-frequency portions. The band dividing unit 31 includes a fixed resistor and an amplifier.
Is the same as that shown in FIG. 33 is a variable resistor VR12
And a filter circuit including a capacitor C9. The band dividing unit 31 and the level control unit 32 are connected via the switch SW1, and the band dividing unit 31
And the filter circuit 33 are connected via switches SW1 and SW2, the level control unit 32 and the filter circuit 33 are connected via switches SW3 and SW2, and the outputs of the level control unit 32 and the filter circuit 33 are connected. Is selected by the switch SW4.

Now, the switch SW1 is set to the a side and the switch S
When W3 is connected to the b side and switch SW4 is connected to the a side, 34
As shown in FIG. 7, a cutoff characteristic of 18 dB / oct is obtained. Next, when the switch SW1 is connected to the a side, the switch SW3 is connected to the a side, the switch SW2 is connected to the b side, and the switch SW4 is connected to the b side, a cutoff characteristic of 12 dB / oct is obtained. Then, the switch SW1 is set to the b side, and the switch SW2 is set.
When the switch SW4 is connected to the a side and the switch SW4 is connected to the b side, 6 dB /
oct is obtained. As described above, by switching the cutoff characteristic of each frequency divided into a plurality of stages, a loudness characteristic suitable for the user's preference can be obtained according to the application.

(Embodiment 4) FIG. 6 shows a configuration of a main part of a loudness control device according to Embodiment 4 of the present invention, and a configuration of a loudness control device main body is the same as that shown in FIG. . This embodiment utilizes the multi-amplifier output terminal 18 of FIG. The left channel low frequency multi-amplifier output terminal 41a, the left channel middle frequency multi-amplifier output terminal 41b, and the left channel high frequency multi-amplifier output terminal 41c are connected via power amplifiers 42a, 42b and 42c, respectively. Speaker 43
a, 43b and 43c are connected. Similarly, power amplifiers 45a, 45b, and 45c are respectively connected to the multi-amplifier output terminal 44a for the right channel low band, the multi-amplifier output terminal 44b for the right channel middle band, and the multi-amplifier output terminal 44c for the right channel high band. Speakers 46a, 46b, and 46c are connected through the speaker. The listening point 47 of the viewer is located at a position surrounded by the speakers.

The audio signals from the multi-amplifier output terminals, which have been divided into bands and adjusted to appropriate volume levels, are amplified by power amplifiers, respectively, and then sound is output from speakers dedicated to each band arranged at predetermined positions. By outputting, in the multi-amplifier system and the multi-speaker system, the viewer can obtain the optimum loudness characteristic 48 at the listening point 47.

(Embodiment 5) FIG. 7 schematically shows loudness control in an on-vehicle acoustic system according to Embodiment 5 of the present invention. As shown in FIG. 7A, in the acoustic system in the vehicle, a high-mid speaker unit 52 is arranged above an instrument panel in front of a front seat 51, and a low-range speaker unit 53 is arranged below a door panel. When viewed from the driver's listening point 54, the sound image position 55 of the sound from the speaker units 52 and 53 is at a relatively low position, so that the sound can be heard from below. For this reason, as shown in FIG. 7B, if the loudness effect is activated by adjusting the volume knob 56 for adjusting the volume, the midrange becomes lower and the sound image position 55 further lowers. Therefore, as shown in FIG. 7 (c), in the loudness control, the frequency range from 1 kHz to about 8 kHz in the middle range is shown in FIG.
By following the change in the volume of the main volume 17, the sound image position 55 can be prevented from lowering.

(Embodiment 6) FIG. 8 shows another example of loudness control in a vehicle-mounted acoustic system according to Embodiment 6 of the present invention. In most cases, the listening point of a normal driver is not at the same distance from the speakers. With the conventional two-channel control loudness control, even if the left and right speakers at the listening point and the front and rear speakers have the same loudness characteristics, Due to the difference in distance from each speaker, the effect of the loudness characteristic was not sufficiently obtained. Therefore, as shown in FIG. 8, the four-channel audio signals of front, rear, left and right are respectively supplied to the variable resistors VR13,
Power amplifiers 61, 62, 6 through 14, 15, 16
Amplified by 3, 64, and speakers 65, 66, 6 respectively
7 and 68, each variable resistor VR
The resistance values of 13, 14, 15, and 16 are individually set, and FIG.
Of the driver's actual listening point 69 by controlling the balance control, which is the left and right sound volume, and the fader control, which is the front and rear sound volume, by individually controlling with the control voltage V for level adjustment from the main volume 17 of the driver. For each speaker 65, 66, 67, 6
8 can be set at a virtual listening point 70 located at the center of the center 8, and the stereo effect can be improved, and an optimum loudness effect can be obtained even at the actual listening point 69.

(Embodiment 7) FIG. 9 illustrates the operation of a loudness control device according to Embodiment 7 of the present invention. The configuration of the device itself is the same as that shown in FIG. In an in-vehicle system, when using the in-vehicle audio system for audio guidance for navigation, when the audio guidance for navigation jumps in while the audio system is operating and listening to music, in the conventional system, In this method, the sound of the front channel was muted and voice guidance was inserted there. However, in this method, the localization of the sound became unstable and the feeling of discomfort during muting was great. Therefore, in the seventh embodiment, the output levels of VCA1 to VCA3 are reduced as shown at 71 by the control voltage V for level control from the main volume 17 for the two channels on the left and right of the front.
The voice guidance signal from the navigation is
By controlling the output level to be increased by CA4, the output mixed by the mix circuit 15 can be output without changing the volume of the synthesized signal of the voice signal and the voice guide signal when the voice guide signal is input as indicated by 73. It is possible to ensure the clarity of the voice guidance signal, and to hear a voice guidance that is easy to hear without a sense of incongruity.

[0030]

According to the present invention, as is apparent from the above embodiment, the audio signal of each channel is divided into bands, and the change of the sound volume of each band with respect to the whole sound volume is controlled for each band to thereby improve the loudness characteristic. It is possible to build an optimal sound system by linking sound quality, balance, and fader control. As a result, sound quality and sound image localization can be controlled while ensuring a sufficient variable amount, and audibility sensitivity correction can be performed in consideration of special reproduction conditions for in-vehicle use and the like.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a loudness control device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an amount of attenuation of a VCA with respect to a control voltage according to the first embodiment of the present invention;

FIG. 3 is a circuit diagram of a main part according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing an operation according to the second embodiment of the present invention.

FIG. 5 is a circuit diagram of a main part according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram of a main part according to a fourth embodiment of the present invention.

FIG. 7 is a schematic diagram showing an operation according to the fifth embodiment of the present invention.

FIG. 8 is a schematic diagram of a main part according to a sixth embodiment of the present invention.

FIG. 9 is a schematic diagram of a main part according to a seventh embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 input selector unit 12 band division unit 13 level control unit 14 buffer 15 mix circuit 16 level control unit 17 main volume 18 multi-amplifier output terminal 19 DSP 20 required loudness characteristics

Claims (14)

[Claims] A frequency is divided into bands to correct the audibility of an input audio signal, and the volume of each of the divided frequencies is changed so as to follow a change in the overall volume of the audio signal output. Loudness control method. 2. The loudness control method according to claim 1, wherein the cut-off frequency of each frequency is changed in accordance with a change in the whole volume during band division. 3. The loudness control method according to claim 1, wherein the cutoff characteristic of each frequency is switched in a plurality of stages during band division. 4. The loudness control method according to claim 1, wherein the audio signal for each frequency, which has been subjected to band division and volume adjustment, is extracted and output from an independent power amplifier and a speaker. 5. The loudness control method according to claim 1, wherein the position of the sound image is changed by changing a specific frequency region among the band-divided frequencies so as to follow a change in the whole volume. 6. An audio system having speakers arranged in front, rear, left and right, wherein a balance control and a fader control are linked in response to a change in the overall volume, so as to optimize at a listening point of a viewer. The described loudness control method. 7. In a vehicle-mounted acoustic system, when a voice guidance signal of another device is input during output of a voice signal,
2. The loudness control method according to claim 1, wherein the level of the frequency-divided mid-range audio signal is attenuated and the level of the audio guide signal is increased. 8. A loudness control comprising: means for dividing a frequency for compensating for perceptual sensitivity; and means for changing the sound volume of each of the band-divided frequencies following a change in the sound volume of the entire audio signal output. apparatus. 9. The loudness control device according to claim 8, further comprising means for changing a cutoff frequency of each frequency at the time of band division by following a change in overall volume. 10. The loudness control device according to claim 8, further comprising: means for switching a cutoff characteristic of each frequency to a plurality of stages during band division. 11. The loudness control device according to claim 8, further comprising: means for extracting an audio signal for each frequency divided into bands and outputting the audio signal from an independent power amplifier and a speaker. 12. The loudness control device according to claim 8, further comprising means for changing the volume of a specific frequency region among the band-divided frequencies following a change in the overall volume. 13. An audio system having speakers at front, rear, left and right, wherein a balance control and a fader control are interlocked according to a change in overall volume,
9. The loudness control device according to claim 8, further comprising means for optimizing at a listening point of the viewer. 14. An on-vehicle acoustic system comprising means for mixing a voice signal and a voice guidance signal of another device,
When a voice guide signal of another device is input during the output of the voice signal, a means is provided for attenuating the level of the frequency-divided mid-range voice signal and increasing the level of the voice guide signal. The loudness control device according to claim 8.