JP2000190785A - On-vehicle acoustic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle acoustic system that can continuously create comfortable listening conditions free from manual control by automatically processing acoustic signals in consideration for that frequency characteristics of travel motion noise which appeals to the auditory sense of humans and giving occupants a volume level appropriately adapted to the auditory sensor of humans. SOLUTION: This on-vehicle acoustic system comprises a microphone 7 for detecting the noise level inside the vehicle interior, a filter 8 for filtering the output signals of the microphone 7 in relation to passband characteristics adapted to frequency characteristics considering the auditory sense of humans, a level control part 9 for detecting the level of the output signals of the filter 8, and a volume correcting means to correct the sound volume by processing acoustic signals out from a sound source 1 in accordance with the detection level of the level control part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted acoustic device such as a vehicle-mounted compact disc (CD) player, and more particularly to running of engine sound, road noise (noise generated by contact between a tire and a road surface) and wind noise. The present invention relates to an in-vehicle acoustic device that controls a volume and the like according to noise.

[0002]

2. Description of the Related Art When listening to music or the like while driving in a car, the running noise such as engine sound, road noise or wind noise sometimes makes it difficult to hear the music or the like. An adjustment operation is required. The running noise is
Since the running speed and the road surface condition change every moment as the running condition changes, it is necessary to adjust the volume every time the running condition changes in order to maintain a desirable sound volume state. Was very troublesome to do. For this reason, an on-vehicle acoustic device having a noise-sensitive volume control function of detecting the noise level in the vehicle cabin using a microphone or the like and automatically controlling the increase or decrease of the volume according to the detected noise level has been realized. I have.

[0003]

However, since the frequency characteristics in the sense of hearing perceived by humans are not flat, even if the noise level is the same, the noise level in hearing perceived by humans differs due to the frequency characteristics of the running noise. come. For this reason, the conventional noise-sensitive volume control function that automatically controls the increase / decrease of the volume according to the simply detected noise level achieves an appropriate sensation of sound for the occupants that is suitable for human hearing. There was a problem that it was not possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and automatically processes an acoustic signal in consideration of the frequency characteristics of the perceived perception of running noises by a human, and adapts the occupant to human perception. By giving a proper sense of volume,
It is an object of the present invention to realize an on-vehicle acoustic device that enables comfortable listening at all times without troublesome human intervention.

[0005]

Means for Solving the Problems and Their Effects To solve the above problems, an on-vehicle acoustic device (1) according to the present invention comprises:
In a vehicle-mounted acoustic device mounted on a vehicle, a noise level detecting means for detecting a noise level in a vehicle interior, and an output signal of the noise level detecting means is filtered with a pass characteristic adapted to a frequency characteristic in human hearing. A filter, a level detecting means for detecting a level of an output signal of the filter, and a sound volume correcting means for processing an acoustic signal from a sound source in accordance with a detection level of the level detecting means and correcting a sound volume. It is characterized by.

According to the on-vehicle acoustic device (1), the noise level in the passenger compartment is detected at a level adapted to the frequency characteristics of human hearing, and the detected noise level is used to process an acoustic signal to produce a sound volume. Is corrected. That is, since the sound signal is processed and the sound volume is corrected in conformity with the noise level felt by humans as a sensation, a comfortable sound volume feeling is given to the occupant.

[0007] A vehicle-mounted acoustic device (2) according to the present invention.
In the above-mentioned in-vehicle acoustic device (1), the sound volume correcting means is configured to include an output increasing / decreasing means for increasing / decreasing the acoustic signal output by an increasing / decreasing amount according to a detection level of the level detecting means. Features. According to the volume control device (2), the sound signal output is increased / decreased by the output increase / decrease means by an increase / decrease amount corresponding to the detection level of the level detection means. As a result, the output level of the acoustic signal is automatically adjusted, and a comfortable sound volume is given to the occupant.

[0008] Further, a vehicle-mounted acoustic device (3) according to the present invention.
Is a vehicle-mounted acoustic device (1) or (2)
The sound volume correction means includes an equalizer for giving a frequency characteristic corresponding to a detection level of the level detection means to the sound signal.
According to the volume control device (3), the frequency characteristics of the audio signal are automatically adjusted by the equalizer in accordance with the noise level perceived by human beings (the signal level increases as the frequency band is more susceptible to noise). ), Reproduction is performed with a more comfortable sound volume to humans.

[0009] A vehicle-mounted acoustic device (4) according to the present invention.
In any one of the above-described on-vehicle audio devices (1) to (3), the sound volume correction unit includes a compressor that compresses the audio signal at a compression rate corresponding to a detection level of the level detection unit. It is characterized by comprising. According to the volume control device (4), the audio signal is compressed at a compression rate corresponding to the noise level perceived by human beings (the smaller the sound that is more susceptible to noise, the higher the signal level), and the more the user can hear the sound. Easy sound reproduction is realized.

[0010] Further, a vehicle-mounted acoustic device (5) according to the present invention.
Comprises a reverberation unit for generating a reverberation signal based on the acoustic signal and adding the reverberation signal to the acoustic signal in any one of the on-vehicle acoustic devices (1) to (4); The means is configured to include reverberation time characteristic control means for controlling a reverberation time characteristic of the reverberation signal. According to the volume control device (5), the reverberation time characteristic of the reverberation signal is adjusted in accordance with the noise level perceived by a human being, and the reverberation time is shortened (when there is no noise) due to the fact that the reverberation sound cannot be heard due to noise. Is no longer audible due to the presence of noise, and the time for which the reverberation sound can be heard is reduced.) It is possible to reproduce a sound signal that is felt by the user.

[0011] Further, an on-vehicle acoustic device (6) according to the present invention.
In any one of the on-vehicle acoustic devices (1) to (5), the sound volume correction means includes a storage means for storing correction data for volume correction in association with a detection level of the level detection means. It is characterized by comprising. According to the volume control device (6), it is possible to obtain correction data for volume correction without performing complicated calculations, to reduce the number of calculation processes, to achieve high-speed processing, and to perform relatively low-speed calculations. It is possible to configure an in-vehicle acoustic device even with a processing device.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a vehicle-mounted acoustic device according to an embodiment of the present invention.

A sound signal from a sound source 1 such as a CD player is processed by an equalizer 2, a compressor 3, and an increase / decrease unit 4, then power-amplified by an amplifier 5, and output as sound from a speaker 6. .

The equalizer 2 adds a frequency characteristic to the sound signal from the sound source 1. In the present embodiment, the equalizer 2 is constituted by a digital signal processing circuit (DSP) for giving the frequency characteristic to the sound signal by digital arithmetic processing. I have.
Note that the equalizer 2 can also be realized by an analog circuit including a capacitor, a coil, a resistor, and the like.

The compressor 3 compresses the output signal of the equalizer 2 (compresses the dynamic range, and raises the signal level more as the level of the signal becomes smaller).
In the present embodiment, the digital signal processor is constituted by a DSP for giving a frequency characteristic to an acoustic signal by digital arithmetic processing. still,
The equalizer 2 can also be realized by an analog circuit whose amplification degree changes according to the input signal level, for example, an operational amplifier whose feedback amount is controlled to be proportional to the input signal level. The increase / decrease unit 4 increases / decreases an output signal of the compressor 3 and can be realized by an electronic volume composed of a ladder resistor or the like whose change rate changes according to an input signal of a control terminal.

The microphone (microphone) 7 converts the noise in the vehicle compartment into an electric signal, and is installed at an appropriate position in the vehicle compartment (a position where the effect of the reproduced sound from the speaker 6 is small). Incidentally, a subtraction means (not shown) for subtracting the reproduced sound of the audio device from the output signal of the microphone 7 may be connected so that only the traveling noise is output to the filter 8.

An output signal from the microphone 7 is given a frequency characteristic in a filter 8. This frequency characteristic is similar to the characteristic of human hearing as shown in the characteristic diagram shown in the lower part of FIG. 1, for example, an inverse characteristic of a loudness curve such as an A-weighted filter.
Is constituted by a resonance circuit. The output signal from the filter 8 is input to the level control unit 9.

The level control unit 9 detects the input signal level, and according to the detected signal level, the equalizer 2,
The compressor 3 and the changer 4 are controlled. The part of the level control unit 9 for detecting the signal level (running noise level) is constituted by a DSP for calculating the average value of the input signal by digital operation, and includes a detection circuit for detecting the envelope of the input signal, and an envelope. An analog circuit including a rectifying and smoothing circuit for rectifying and smoothing the detection signal can be used.

The part of the level control section 9 for controlling the equalizer 2 and the like is constituted by a microcomputer, and includes an equalizer 2, a compressor 3, and an increase / decrease device 4.
Output the control data to control the characteristics of the equalizer 2, the compressor 3, and the reducer 4. The level control unit 9 is connected to a memory 10 that stores the detection level of the traveling noise and the control data of the equalizer 2, the compressor 3, and the changer 4 in association with each other.

The level controller 9 reads control data corresponding to the running noise level from the memory 10 and processes the data read from the memory 10 based on the specified sound volume data specified by the occupant by operating a switch or the like.
The control data corresponding to each of the compressor 3 and the changer 4 is output. For example, if the running noise amount is N2 and the designated volume data is -Vdb, as shown in the table of FIG. 1, the equalizer 2 has an EQ value of E2, the compressor 3 has a compression ratio of A2%, and -(V + V2) db is output from the level controller 9 as control data to the adjuster 4 as an increase / decrease amount.

Next, the running noise characteristics of the equalizer 2, the compressor 3, and the changer 4 will be described. FIG. 2 (A),
(B) and (C) are characteristic diagrams showing running noise characteristics of the equalizer 2, the compressor 3, and the changer 4.

As shown in FIG. 2A, the frequency characteristic of the equalizer 2 is such that the higher the running noise level, the lower the treble range and the higher the frequency range.
As the running noise increases, the sound signal level in the band where the sensitivity of human hearing is low is increased to realize sound reproduction that is easy to hear.

As shown in FIG. 2B, the input / output signal level characteristics of the compressor 3 become higher as the running noise level becomes higher.
It has the characteristic of boosting a small volume signal greatly. In cooperation with the operation of the filter 8, the level of a small sound is raised as the running noise is larger, especially as the running noise in the human voice band (middle sound range) is larger. This realizes sound reproduction that makes it easy to hear small sounds.

The input / output signal level characteristics of the changer 4 are shown in FIG.
As shown in (C), as the running noise level is higher, the signal level is greatly increased over the entire band. In cooperation with the operation of the filter 8, the running noise is larger, especially the human voice band. As the running noise in the (middle tone range) increases, the sound level is raised as a whole, that is, the volume is increased, so that sound reproduction that is easy to hear even when the running noise increases is realized.

Each of these controls allows the occupant to listen to music and the like at a comfortable volume level even if the running noise level rises and falls as the running noise level rises. Further, in the present embodiment, all the controls of the equalizer 2, the compressor 3, and the increase / decrease unit 4 are performed in accordance with the running noise. However, a considerable effect can be obtained by a single control or a control using a combination of two types. It is possible to do.

Next, an on-vehicle acoustic device according to a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing a vehicle-mounted acoustic device according to the second embodiment.
Note that the same components as those of the vehicle-mounted acoustic device according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, an acoustic signal from the sound source 1 is input to a reverberation generator 11 to generate a reverberation sound, and the generated reverberation sound is mixed by a mixer (adder) 12 with the sound from the sound source 1. Mix with signal. Then, the signal level of the mixed acoustic signal is adjusted by the adjuster 4, the power is amplified by the power amplifier 5, and reproduced from the speaker 6 as sound.

In the present embodiment, the reverberation generation unit 11 generates a reverberation sound from a sound signal by digital arithmetic processing.
P. The reverberant sound can be generated by, for example, delaying and level-adjusting an output signal, and adding the result to an input signal. The reverberation time characteristics of the reverberation sound to be generated can be controlled by the delay characteristics and the level adjustment characteristics. Note that the reverberation generation unit 11 can also be realized by an analog circuit such as a delay element or an operational amplifier.

The level control section 9 reads out control data corresponding to the running noise level from the memory 10, processes the data read out from the memory 10 based on the specified sound volume data specified by the occupant by operating a switch, etc. , And outputs corresponding control data to the reverberation generation unit 11. For example, if the running noise is N3 and the designated volume data is −Vdb, as shown in the table of FIG. 3, the increase / decrease unit 4 has − (V + V3) db as the increase / decrease amount, and the reverberation generation unit 11 has The reverberation value Z3 is output from the level control unit 9 as control data as reverberation time characteristics.

Next, the running noise characteristic of the reverberation generator 11 will be described. FIG. 4 is a characteristic diagram showing a running noise characteristic of the reverberation generator 11. As shown in FIG. 4, the reverberation time characteristics of the reverberation generation unit 11 are such that as the running noise level is higher, the signal level is increased or the compression ratio is increased (lower reverberation pitch, the level is greatly increased). In cooperation with the operation of the filter 8, as the running noise increases, the amount of attenuation of the reverberation sound with respect to time is suppressed, and the time at which the reverberation sound is actually recognized by the human ear even when the running noise level changes. In other words, the time until the reverberation sound is drowned out by the running noise does not change much. For this reason,
Even if the running noise level changes, the sound field effect due to reverberation can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a vehicle-mounted acoustic device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing running noise characteristics of an equalizer, a compressor, and a changer.

FIG. 3 is a block diagram showing a configuration of a vehicle-mounted acoustic device according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a running noise characteristic of a reverberation generation unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sound source 2 ... Equalizer 3 ... Compressor 4 ... Increase / decreaser 9 ... Level control part 10 ... Memory 11 ... Reverberation generation part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideki Matsui 1-2-28 Goshodori, Hyogo-ku, Kobe-shi, Hyogo F-term in Fujitsu Ten Limited (Reference) 3D020 BA02 BB01 BC01 BE03 BE04

Claims (6)

[Claims] 1. An on-vehicle acoustic device mounted on a vehicle, wherein a noise level detecting means for detecting a noise level in a vehicle interior, and an output signal of the noise level detecting means are adapted to frequency characteristics in human hearing. A filter for filtering with a pass characteristic; a level detecting means for detecting a level of an output signal of the filter; a volume correcting means for processing an acoustic signal from a sound source in accordance with a detection level of the level detecting means and correcting a volume. An on-vehicle acoustic device comprising: 2. The apparatus according to claim 1, wherein said sound volume correcting means includes an output increasing / decreasing means for increasing / decreasing said audio signal output by an increasing / decreasing amount according to a detection level of said level detecting means. In-vehicle acoustic device. 3. The sound volume correcting means includes an equalizer for giving a frequency characteristic corresponding to a detection level of the level detecting means to the sound signal. 2. The on-vehicle acoustic device according to 2. 4. The apparatus according to claim 1, wherein said volume correction means includes a compressor for compressing said audio signal at a compression ratio corresponding to a detection level of said level detection means. 4. The on-vehicle acoustic device according to any one of the above items 3. 5. A reverberation unit for generating a reverberation signal based on the acoustic signal and adding the reverberation signal to the acoustic signal, wherein the volume correction unit controls a reverberation time characteristic of the reverberation signal. The in-vehicle acoustic device according to any one of claims 1 to 4, further comprising a time characteristic control unit. 6. The apparatus according to claim 1, wherein said volume correction means includes a storage means for storing correction data for volume correction in correspondence with a detection level of said level detection means. 6. The on-vehicle acoustic device according to any one of the items 5 to 5.