JP2592009Y2 - Sound field characteristic adjustment 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 sound field characteristic adjusting device for automatically correcting a sound image localization and a sound field frequency characteristic of an audio signal in an audio system having a plurality of speakers.

[0002]

2. Description of the Related Art In an audio system having a plurality of speakers, it is desirable to localize a sound image at a position of a listener and to create a sound field characteristic adapted to a space around the listener. In other words, it is desirable that the sound output from each speaker reaches the listener's ear at the same time, and that the frequency characteristics are set to predetermined characteristics. Conventionally, in order to localize the sound image, a skilled person fine-tunes the mounting position of the speaker,
(Digital signal processor) to delay the sound of each speaker digitally. In order to make the frequency characteristic of the sound field a predetermined characteristic, for example, a center frequency and a bandwidth of each band are adjusted using a manual parametric equalizer device.

[0003]

However, the conventional sound image localization adjustment and sound field frequency characteristic adjustment cannot be easily performed by ordinary listeners, but are complicated and almost impossible for non-experts. Further, each time the speaker position or the listening position changes, it is necessary to perform troublesome sound image localization adjustment and sound field frequency characteristic adjustment. In particular, in the case of home audio, the speaker position, the listening position, and the listening room are often changed. In the case of in-vehicle audio, the speaker position and the listening room are fixed, but the listening position differs depending on the front and rear of the driver's seat. Further, there are cases where it is desired to change the seat position at which the sound image is to be localized. In view of the above, it is an object of the present invention to provide a sound field characteristic adjusting device which can easily localize a sound image at a desired position and make a sound field frequency characteristic a predetermined characteristic.

[0004]

In order to achieve the above object, in a sound field characteristic adjusting device for an audio system having a plurality of speakers, an impulse generator for generating an impulse signal, and at least two or more outputs are provided. A first selector unit that has a terminal, receives an impulse signal from the impulse generator, selectively outputs the impulse signal by selectively switching the output terminal, and a pink noise generator that generates pink noise. Second selector means for selectively switching between pink noise from the pink noise generator and an impulse signal output from the first selector means and outputting the result to a predetermined speaker; A microphone for detecting a signal, and an impulse from each speaker by the first selector means and the second selector means. When a signal is output, the microphone detects the impulse signal, and for each speaker, a time measuring means for measuring a time required for the speaker to reach the microphone, and a measuring time measured by the time measuring means. A delay time calculating means for calculating a delay time of each audio signal output from each speaker based on the microphone when the pink noise added with the delay time is output from each speaker by the second selector means; It has a sound field frequency analyzing means for detecting the pink noise and performing a frequency analysis of a sound field based on the pink noise, and an audio frequency correcting means for correcting a frequency characteristic of an audio signal by the sound field frequency analysis. And

[0005]

In the sound field characteristic adjusting device, when an impulse signal is output from each speaker by the first selector means and the second selector means, the impulse signal is detected by the microphone, and the speaker is connected to the microphone for each speaker. The time until the arrival is measured, and the delay time of each audio signal output from each speaker is calculated based on the measured time.

When the second selector outputs pink noise to which a delay time is added from each speaker, the microphone detects the pink noise and analyzes the frequency of the sound field based on the pink noise from each speaker. And
The frequency characteristics of the audio signal are corrected by sound field frequency analysis. With this configuration, the measurement of the delay time of each speaker and the measurement of the acoustic characteristics in the sound field can be performed by an integrated device instead of separately, so that the measurement time is reduced, and the localization of the sound image and the sound field frequency characteristics are easily set. be able to. Such means can be easily realized by, for example, a DSP (Digital Signal Processor).

[0007]

FIG. 1 is a block diagram of a sound field characteristic adjusting apparatus according to an embodiment of the present invention, which is applied to an on-vehicle audio system. In the following, suffix LF
Denotes a left channel front, RF denotes a right channel front, LR denotes a left channel rear, and RR denotes a right channel rear. In FIG. 1, reference numeral 11 denotes a left-channel audio signal AL0 and a right-channel audio signal A.
An audio circuit that outputs R0. 12 is DSP
(Digital signal processor) and has the following configuration.

Reference numeral 13 denotes an impulse generator that generates an impulse signal IP, 14 denotes a first selector that selectively switches and outputs an impulse signal IP generated from the impulse generator from four output terminals, and 15 generates a pink noise PN. A pink noise generator 16 corrects the center frequency and bandwidth of each band of the audio signals AL0 and AR0 from the audio circuit section 11, and outputs parametric equalizer sections as audio signals AL and AR, respectively. A delay unit 18 delays the audio signals AL and AR by a predetermined time so that the audio signals AL and AR are at desired localization positions. The delay unit 18 includes an impulse signal IP output from the impulse generator 13 via the first selector 14 and an output signal from the delay unit 17. Switch 18L to select each and send to each speaker
A second selector having F, 18RF, 18LR, and 18RR.

Reference numerals 19LF, 19RF, 19LF, and 19RR denote amplifiers for amplifying a signal input to each speaker, and 20LF and 20R.
F, 20LF, and 20RR are a left channel front speaker, a right channel front speaker, a left channel rear speaker, and a right channel rear speaker, respectively. Each of the speakers 20LF, 20RF, 20LR, and 20RR is arranged at the position shown in FIG.

Reference numeral 21 denotes a position Q at which a sound image is to be localized (FIG. 2).
Microphone that detects sound in the sound field (vehicle compartment)
Is sampled at a predetermined sampling cycle with a microamplifier 23 for amplifying the sound detection signal SM of the microphone 21 and A
AD converter 2 for D (analog / digital) conversion
4 is an impulse signal detector, 25 is a sound detection signal S
Micro-amplifier 26 for amplifying M and the micro-amplifier 2
6 is a pink noise detection circuit 25 including a filter circuit 27 having a plurality of different BPFs (bandpass filters) to which the output signal of 6 is supplied and an AD converter 28 that performs sampling and AD conversion at a predetermined sampling period.

Reference numeral 29 denotes a control unit comprising a microcomputer, which sets a sound image localization and a sound field frequency.
Explaining the former, a peak point based on the impulse signal IP is detected from the sound detection signal SM from the microphone 21, and the time (sound arrival time) from the impulse generation time to the peak point detection time is measured, and the measured sound is measured. The time inversely proportional to the arrival time is set in the delay unit 17 as delay times DLF, DRF, DLR, and DRR.

The latter will be described.
The center frequency of the PF is determined by the parametric equalizer 16.
The control unit 29 instructs the sound detection signal SM to be separated into each band by the filter circuit 27, takes in the separated signal AD-converted by the AD converter 28, and sets the correction coefficient of each band to a parametric coefficient. Set in the equalizer unit 16.

When each setting is completed, the audio circuit 11
The left channel audio signal AL0 and the right channel audio signal AR0 output from are subjected to frequency correction by a parametric equalizer section 16 and input to the delay section 17 as audio signals AL and AR, respectively. Delay unit 17
Then, the left channel audio signal AL is converted to the time DLF, DRF
Audio signals ALF and ALR with only a delay. Also, the right channel audio signal AR is delayed by time DRF, DRR to be audio signals ARF, ARR.

The audio signals ALF and ALR are passed through a second selector 18 and amplifiers 19LF and 19LR to the left channel front and left channel rear speakers 20LF and 2LR.
Input to 0LR. Audio signal ARF,
The ARR is input to the right channel front and right channel rear speakers 20RF and 20RR via the second selector 18 and the amplifiers 19RF and 19RR. 30 is the control unit 2
Reference numeral 9 denotes a key input unit for instructing sound field characteristic adjustment and the like.

This embodiment is configured as described above and operates as follows. First, when the sound from the audio source is turned off and the sound field characteristic adjustment is instructed by the key input unit 30 in a state where the microphone 21 is located at the position where the sound image is to be localized, the impulse signal IP Is generated, and the impulse signal is switched between the first selector 14 and the second selector 18 to control the amplifier 19.
Lead to LF, left channel front direction speaker 20LF
And radiate as sound.

Next, the microphone 21 detects the sound in the sound field,
The microphone detection signal SM is amplified by the microamplifier 23 of the impulse signal detection circuit 22 and input to the AD converter 24. The AD converter 24 samples the microphone detection signal SM at high speed and performs AD conversion. The control unit 29 measures the time required for the impulse signal IP to reach the microphone 21 from the speaker 20LF, and sets the delay time DLF calculated based on the measured time in the delay unit 17. The same processing is sequentially repeated in the right channel front direction, the left channel rear direction, and the right channel rear direction as shown in FIG. 2, and the respective delay times are set in the delay unit 17 as DRF, DLR, and DRR.

When the sound image localization is completed, according to this embodiment, the pink noise generator 14 generates pink noise PN having flat frequency characteristics in order to automatically set the sound field frequency in accordance with a command from the control unit 29. , The pink noise PN to the parametric equalizer section 16 and to the delay section 17 without the equalizing operation. Delay unit 17
Delays the pink noise PN by the delay time set before,
The selector switches 18LF, 18RF, 18LR, and 18RR of the second selector 18 are switched based on a command from the control unit 29, and input to the speakers 20LF, 20RF, 20LR, and 20RR via the amplifiers 19LF, 19RF, 19LR, and 19RR, and radiate as sound. .

Next, the microphone 21 detects a sound in the sound field, amplifies the sound detection signal SM by the microamplifier 26 of the pink noise detection circuit 25, and inputs the amplified signal to the filter circuit 27. The filter circuit 27 forms a band-pass filter corresponding to the center frequency of each band of the parametric equalizer 16 and is controlled by the controller 29. That is, for example, when a band is set to a certain band, the sound detection signal SM passing through the band is input to the AD converter 28, and the AD converter 28 samples the sound detection signal SM at high speed and performs AD conversion. The control unit 29 is DSP1
2 and outputs the correction coefficient to the parametric equalizer 16. Such processing is sequentially repeated for each band, and is repeated in the left channel front direction, the right channel front direction, the left channel rear direction, and the right channel rear direction, and the respective correction coefficients are set in the parametric equalizer unit 16.

In this state, when the left channel and right channel audio signals AL0 and AR0 output from the audio circuit section 11 are input to the parametric equalizer section 16 and the delay section 17, the former corrects the frequency of the audio signal. In the latter, the audio signal is delayed by the delay time and input to each amplifier. That is, the parametric equalizer 16 operates to flatten the sound field frequency characteristics, the delay 17 delays the left channel audio signal AL by the time DLF, DLR, and inputs it to the amplifiers 19LF, 19LR. Input audio signals ALF, ALR
Is amplified and input to the left channel front and left channel rear speakers 20LF and 20LR.

The delay unit 17 delays the right channel audio signal AR by time DRF and DRR, and amplifies the amplifier 19R.
F, 19RR, and the respective amplifiers amplify the input audio signals ARF, ARR and input them to the right channel front and right channel rear speakers 20RF, 20RR. As described above, the sound image localization and the sound field frequency characteristics of the audio signal in the vehicle-mounted audio system can be achieved.

In this embodiment, the sound image localization and the sound field frequency characteristics of the audio signal in the audio system are simultaneously performed only by one key input, but they may be individually performed by, for example, a key input operation. The sound detection signal from the microphone may be selectively switched by the selector means and input to the impulse detection circuit or the pink noise detection circuit. Further, the number of speakers may be plural, and the number of switches of the first and second selectors may be provided according to the number of speakers.

[0022]

As described above, according to the present invention, when an impulse signal is output from each speaker by the first selector means and the second selector means in the sound field characteristic adjusting apparatus, the impulse signal is output by the microphone. , Measuring the time from each speaker to the microphone for each speaker, calculating the delay time of each audio signal output from each speaker based on the measured time,
When the second selector outputs pink noise with a delay time added from each speaker, the microphone detects the pink noise and analyzes the frequency of the sound field based on the pink noise from each speaker. Since the frequency characteristics of the audio signal are corrected by the field frequency analysis, the measurement of the delay time of each speaker and the measurement of the acoustic characteristics in the sound field can be performed by an integrated device instead of separately. There is an effect that the localization and the sound field frequency characteristics can be easily set. Such means can be easily realized by, for example, a DSP (Digital Signal Processor).

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a layout diagram of speakers in a vehicle cabin.

[Explanation of symbols]

12 DSP (Digital Signal Processor) 13 Impulse Generator 14 First Selector 15 Pink Noise Generator 18 Second Selector 20LF, 20RF, 20LR, 20RR Speaker 21 Microphone 22 Impulse Signal Detection Circuit 25 Pink Noise Detection Circuit 29 Control Unit

Claims (1)

(57) [Scope of request for utility model registration] 1. An apparatus for adjusting a sound field characteristic in an audio system having a plurality of speakers, comprising: an impulse generator for generating an impulse signal; and at least two output terminals, the impulse signal from the impulse generator And first selector means for selectively switching the output terminal to output the impulse signal; a pink noise generator for generating pink noise; and a pink noise from the pink noise generator and the first noise generator. Second selector means for selectively switching an impulse signal output from the selector means to output the signal to a predetermined speaker; a microphone arranged in an acoustic space for detecting an acoustic signal; and the first selector means. And when the impulse signal is output from each speaker by the second selector means, A time measuring means for detecting an impulse signal and measuring a time required for each speaker to reach the microphone from the speaker; and an audio signal output from each speaker based on the measuring time measured by the time measuring means. Delay time calculating means for calculating a delay time; and when the pink noise to which the delay time has been added is output from each speaker by the second selector means, the microphone detects the pink noise and outputs the pink noise. A sound field characteristic adjusting device, comprising: a sound field frequency analyzing means for analyzing a frequency of a sound field based on the sound field frequency; and an audio frequency correcting means for correcting a frequency characteristic of an audio signal by the sound field frequency analysis.