JPH0720877A - Acoustic reproduction device - Google Patents

Abstract

PURPOSE:To provide a superior acoustic reproduction device which provides a confortable listening environment under any noisy condition. CONSTITUTION:The device consists of a DSP 21 which performs tone quality correction to acoustic signals that are inputted in accordance with prescribed level control signals and outputs acoustically processed signals, a speaker 24 which sends output voice in accordance with the processed signals, a microphone 46 which collects the output voice and environmental noise and detects synthetic signals, a synthetic level detection section 40a which detects the synthetic signals and synthetic level signals, an acoustic level detection section 40b which detects the processed signals and detects the acoustic level signals, a subtracting circuit 41 which subtracts the acoustic level signals from the synthetic level signals and generates noise level signals and a microcomputer 42 which outputs level control signals in accordance with the noise level signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound reproducing device used in the interior of a vehicle such as an automobile, a ship, an aircraft, etc., and particularly to an auditory system caused by noise generated while the vehicle is running. The present invention relates to a sound reproducing device that automatically removes a masking phenomenon.

[0002]

2. Description of the Related Art Conventionally, an in-vehicle sound reproducing device has been considered as such a sound reproducing device. FIG. 2 is a block diagram showing an outline of a vehicle-mounted sound reproducing device in the prior art.

In FIG. 2, an on-vehicle sound reproducing device includes a sound source 10 such as a tape deck for reproducing a magnetic tape and a radio tuner for receiving a radio broadcasting station, and the sound source 1.
An audio correction output unit 20 that corrects the sound quality of the sound signal output from 0 and outputs the sound, and a sound quality correction control unit 30 that controls the sound quality correction of the sound signal according to running noise.

The acoustic correction output unit 20 is provided with the sound source 10.
A digital signal processor (hereinafter, simply referred to as a DSP) 21 that performs sound quality correction on an acoustic signal from the DSP, and the DSP.
Volume 22 for adjusting the level of the output signal from 21
And an amplifier 23 that amplifies the output signal adjusted by the volume 22, and a speaker 24 that outputs the output signal amplified by the amplifier 23 as sound. The DSP 21 includes an A / D conversion circuit and a D / A conversion circuit.

The sound quality correction control section 30 includes a microphone 31 for collecting output sound from the speaker 24 and traveling noise in the vehicle, an amplifier 32 for amplifying an output signal from the microphone 31, and the amplified signal. A low-pass filter circuit (hereinafter, simply referred to as an LPF) 33 that extracts a low band in a frequency band of an output signal, a vehicle speed detection unit 34 that detects a vehicle speed, and an engine speed detection unit 35 that detects an engine speed. , And a microcomputer (hereinafter, simply referred to as a microcomputer) 36 that controls the DSP 21 and the sound quality correction control unit 30 as a whole. The microcomputer 36 includes an A / D conversion circuit.

Next, the operation of the vehicle-mounted sound reproducing device configured as described above will be described. The acoustic correction output unit 2
The DSP 21 of 0 performs sound quality correction on the acoustic signal output from the sound source 10 according to a level control signal described later,
An acoustically processed signal is supplied to the volume 22. The volume 22 adjusts the output level of the sound processing signal and supplies it to the amplifier 23. The amplifier 23 amplifies the acoustically processed signal and supplies the amplified signal to the speaker 24.
Outputs the acoustically processed signal as a voice.

Microphone 3 of the sound quality correction control unit 30
Reference numeral 1 collects the output sound output from the speaker 24 and the running noise in the vehicle compartment, for example, the noise generated according to the vehicle speed and the engine speed, and amplifies the synthesized signal 32.
Supply to. The amplifier 32 amplifies the combined signal to L
Supply to PF33. The LPF 33 extracts the low frequency band of the combined signal and supplies it to the microcomputer 36.

The vehicle speed detector 34 detects the current vehicle speed and supplies a vehicle speed signal to the microcomputer 36. The engine speed detector 35 detects the current engine speed and outputs the engine speed signal. It is supplied to the microcomputer 36.

The microcomputer 36 estimates an accurate traveling noise level from the composite signal according to the vehicle speed signal and the engine speed signal, and supplies an accurate level control signal to the DSP 21 according to the traveling noise level. .

Therefore, according to the conventional vehicle-mounted sound reproducing device, the microcomputer 36 generates a level control signal based on the running noise, and the DSP 21 responds to the level control signal by outputting the sound signal from the sound source 10. Control, the low frequency band that is easily masked by noise and the amplification of the entire band are performed, so that the masking phenomenon of the auditory system due to noise can be automatically removed and a good listening environment can be obtained. .

[0011]

However, according to the above-mentioned conventional sound reproducing device, the level control signal depending on the running noise level obtained by the vehicle speed signal and the engine speed signal does not only affect the running noise but also the road surface. There is a problem that it is not possible to cope with the masking phenomenon due to vibration noise and noise from outside the vehicle, such as noise from the construction site during construction and noise when the vehicle is stopped, depending on the situation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an excellent sound reproducing device which can obtain a comfortable listening environment under any noise condition.

[0013]

In order to achieve the above object, the present invention provides a sound quality correction means for performing sound quality correction on an audio signal input according to a predetermined level control signal and outputting a sound processed signal. A voice output means for transmitting an output voice according to the acoustic processed signal, a noise detecting means for collecting the output voice and environmental noise and detecting a synthesized signal, and a synthesized level signal for detecting the synthesized signal And a sound level detecting means for detecting the sound processing signal to detect a sound level signal, and an arithmetic processing means for subtracting the sound level signal from the sound level signal to generate a noise level signal. And a control means for outputting the level control signal according to the noise level signal.

[0014]

With this configuration, the control means generates the level control signal based on not only the running noise but also the environmental noise such as the vibration noise due to the road surface condition, the noise from outside the vehicle, the noise generated when the vehicle is stopped, and the like. By correcting the sound quality of the sound signal from the sound source without degrading the sound quality according to the level control signal, it is possible to automatically remove the masking phenomenon caused by any noise and obtain a comfortable listening environment. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sound reproducing device of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an outline of an on-vehicle sound reproducing device to which the sound reproducing device of the present invention is applied. The same parts as those of the conventional technology are designated by the same reference numerals, and their configurations and operations are omitted.

In FIG. 1, the on-vehicle sound reproducing device comprises a sound source 10, a sound correction output section 20 for correcting the sound quality of the sound signal from the sound source 10 according to a level control signal, which will be described later, and outputting the sound, and the sound quality. The level control is performed by detecting the noise level based on a combined signal that combines the corrected acoustic signal and environmental noise such as vibration noise, noise from outside the vehicle, traveling noise, and noise generated when the vehicle is stopped. And a sound quality correction control unit 40 that outputs a signal.

The acoustic correction output section 20 includes a DSP 21, which is a sound quality correction means, a volume 22 and an amplifier 23.
And a speaker 24 which is an audio output means.

The sound quality correction control section 40 includes an acoustic level detecting section 40a which is an acoustic level detecting means for detecting the level of an acoustic signal, and a synthetic level detecting section 40b which is a synthetic level detecting means for detecting the level of environmental noise. Depending on the output from the subtraction circuit 41, which is an arithmetic processing means for subtracting the level output from the synthesis level detection unit 40b from the level output from the acoustic level detection unit 40a, It has a microcomputer 42 which is a control means for outputting a level control signal.

The sound level detecting section 40a includes an amplifier 4
3a and LPF 44a, and a full-wave rectifier circuit 45a that rectifies the output signal from the LPF 44a to an absolute value, and the combined level detection unit 40b includes a microphone 46 that is noise detection means and an amplifier 43b. LPF44b
And a full-wave rectification circuit 45b.

Next, the operation of the on-vehicle sound reproducing apparatus of the present invention configured as described above will be described.

The DSP 21 corrects the sound quality of the sound signal from the sound source 10 according to a level control signal described later and supplies a sound processing signal to the volume 22. The volume 22 adjusts the level of the sound processing signal to amplify each of the amplifiers 2 of the sound correction output unit 20 and the sound level detection unit 40a.
Supply to 3, 43a. The amplifier 23 amplifies the acoustically processed signal, and outputs the sound through a speaker 24.

The amplifier 43a of the sound level detector 40a amplifies the sound processed signal and supplies it to the LPF 44a. The LPF 44a extracts the low frequency band of the acoustic processing signal and supplies it to the full-wave rectification circuit 45a. The full-wave rectifier circuit 45 a rectifies the low frequency band of the acoustic processed signal and converts it into an absolute value to generate an acoustic level signal, and supplies the acoustic level signal to the subtraction circuit 41.

The microphone 46 picks up the output voice and the environmental noise output from the speaker 24 and supplies a synthesized signal to the amplifier 43b. The amplifier 43b
Supplies the combined signal to the LPF 44b after amplifying it. The LPF 44b extracts the low frequency band of the combined signal and supplies it to the full-wave rectifier circuit 45b. The full-wave rectification circuit 45b
Generates a composite level signal by rectifying the low frequency band of the composite signal and converting it to an absolute value, and supplies the composite level signal to the subtraction circuit 41.

The subtraction circuit 41 subtracts the sound level signal from the combined level signal to generate a noise level signal, and supplies the noise level signal to the microcomputer 42. The microcomputer 42 supplies a level control signal to the DSP 21 according to the noise level signal.

According to the above embodiment, the microcomputer 42
Generates a level control signal based on not only running noise but also environmental noise such as vibration noise due to road surface conditions, noise from outside the vehicle, and noise generated when the vehicle is stopped, and the sound quality is degraded according to the level control signal. By performing sound quality correction on the acoustic signal from the sound source 10 without doing so, a masking phenomenon due to any noise can be automatically removed, and a comfortable listening environment can be obtained.

Further, the sound quality correction control unit 40 has the LPF 4
The reason why 4a and 44b are used is to generate a level control signal based on the level of the low frequency band, which is the main component of noise, and to reliably prevent masking of the low frequency band of the acoustic signal from the sound source 10. You can

Further, each LPF 44 of the sound quality correction control unit 40
By providing a high-pass filter circuit for high-frequency detection of each low frequency band after extracting the low frequency bands of a and 44b, the frequency band of the extracted noise can be further limited.

Further, a peak level detection circuit (not shown), which is a discriminating means for detecting whether or not the level of the sound signal from the sound source 10 exceeds a prescribed level, is provided before the sound quality correction processing of the DSP 21, and the peak is detected. If the result of the level detection circuit is sent to the microcomputer 42 and the microcomputer 42 outputs the level control signal so as to increase the gain only when the level is below the specified level based on the result, the level of the acoustic signal is increased. It is possible to surely prevent the discomfort in hearing due to excess.

In addition, the volume 22 has a DSP 21
Is provided with a discrimination function for detecting whether or not the level of the sound-processed signal from the specified level exceeds a prescribed level, and the result of the discrimination function is sent to the microcomputer 42. Only by outputting the level control signal, it is possible to surely prevent the sense of incongruity due to hearing from being caused by exceeding the level of the sound processing signal.

Further, the microcomputer 42 has a function of averaging the noise level signals from the subtraction circuit 41, which are sequentially input, at regular time intervals and outputting a level control signal in accordance with the averaged noise level signal. By making the level control signal multi-staged and performing signal processing according to each stage, smooth signal processing can be performed even when a large level noise is temporarily generated. You can

Further, the maximum change amount between the noise level signal averaged at every constant time and the next averaged noise level signal is defined, and when the maximum change amount is exceeded,
If the microcomputer 42 is provided with a function of outputting a level control signal according to the next averaged noise level signal, the sound quality correction can be made to work more smoothly acoustically.

In the above embodiment, the microcomputer 42 is separately provided in order to reduce the processing load of the DSP 21, but all the processing of the microcomputer 42 is performed by the DSP 21.
It may be done in.

[0033]

According to the sound reproducing apparatus of the present invention configured as described above, the sound quality correcting means for correcting the sound quality of the sound signal input according to the predetermined level control signal and outputting the sound processed signal. A sound output means for outputting the sound-processed signal as an output sound, a noise detection means for collecting the output sound and environmental noise to detect a synthesized signal, and a synthesized level signal for detecting the synthesized signal. Synthetic level detecting means for detecting, acoustic level detecting means for detecting the acoustic processed signal to detect the acoustic level signal, and arithmetic processing for subtracting the acoustic level signal from the synthetic level signal to generate a noise level signal And a control means for outputting the level control signal according to the noise level signal.

Therefore, not only the running noise but also the vibration noise due to the road surface condition, the noise from the outside of the vehicle,
Generates a level control signal based on environmental noise such as noise generated when the vehicle is stopped, and performs sound quality correction on the sound signal from the sound source according to the level control signal without degrading the sound quality, thereby eliminating any noise. It is possible to automatically remove the resulting masking phenomenon and obtain a comfortable listening environment.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a vehicle-mounted sound reproduction device to which a sound reproduction device of the present invention is applied.

FIG. 2 is a block diagram showing an outline of a vehicle-mounted sound reproduction device to which a sound reproduction device according to the related art is applied.

[Explanation of symbols]

 21 DSP (sound quality correction means) 24 Speaker (audio output means) 40a Sound level detection section (sound level detection means) 40b Synthesis level detection section (synthesis level detection means) 41 Subtraction circuit (calculation means) 42 Microcomputer (control means) 46 Microphone (noise detection means)

Claims (7)

[Claims] 1. A sound quality correction means for correcting a sound quality of an input sound signal according to a predetermined level control signal and outputting a sound processed signal, and a sound output means for outputting an output sound according to the sound processed signal. A noise detecting means for collecting the output voice and environmental noise and detecting a combined signal; a combined level detecting means for detecting the combined signal to detect a combined level signal; and detecting the acoustic processing signal. Acoustic level detecting means for detecting an acoustic level signal, arithmetic processing means for subtracting the acoustic level signal from the combined level signal to generate a noise level signal, and outputting the level control signal according to the noise level signal And a control means for controlling the sound reproduction apparatus. 2. The sound reproducing apparatus according to claim 1, wherein the synthesis level detecting means and the sound level detecting means are low frequency detection. 3. The sound reproducing apparatus according to claim 2, wherein high frequency detection is added to the synthesis level detecting means and the sound level detecting means. 4. A determination means is provided for determining whether or not the level of the acoustic signal of the acoustic output means is below a prescribed level, and the control means is provided only when the level of the acoustic signal is below the prescribed level. The sound reproducing device according to claim 1, wherein the level control signal is output. 5. A determination means is provided for determining whether or not the level of the sound processing signal of the sound quality correction means is below a specified level, and the control means is provided only when the level of the sound processing signal is below the specified level. The sound reproducing device according to claim 1, wherein the sound reproducing device outputs the level control signal. 6. The control means averages the noise level signals that are sequentially input at regular time intervals, and outputs a level control signal according to the averaged noise level signals. The sound reproducing device according to claim 1. 7. A maximum change amount between a noise level signal averaged at every fixed time and a noise level signal averaged next time is defined, and when the maximum change amount is exceeded, 7. The sound reproducing device according to claim 6, wherein a level control signal corresponding to the averaged noise level signal is output.