JP3374546B2 - Sound reproduction 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 reproducing device used in a transporting machine such as an automobile, a ship, an airplane, etc. Regarding the device.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing an example of a conventional sound reproducing apparatus of this type, and shows a case where it is applied to an on-vehicle audio device. In FIG. 2, a tape,
The level of a music signal from a sound source 201 such as a radio is adjusted by a volume adjusting means 202 and a power amplifier 203 and reproduced by a speaker 204. The running noise is detected by the microphone 205 placed inside the vehicle, and the detection band is limited by the low-pass filter 207. The microphone signal, the vehicle speed signal 208, and the engine speed signal 209 are input to the microcomputer 210, and the noise level in the vehicle compartment is estimated. The microcomputer 210 controls the volume adjusting means 202 according to the estimated noise level to increase the volume of the reproduction signal.

[0003]

However, in the above-mentioned conventional sound reproducing apparatus, the microphone 205 includes not only the traveling noise but also the reproduced music signal. Therefore, the vehicle speed signal 208 and the engine speed signal 209 are used to accurately estimate the running noise.
However, the method of placing the center of gravity on the vehicle speed signal and the engine speed signal cannot increase the volume unless the actual speed rises, and responds to changes in running noise due to opening and closing of windows and road conditions even at constant speed running. There was a problem that I could not.

The present invention solves such conventional problems, and an object of the present invention is to provide an excellent sound reproducing device capable of obtaining a comfortable listening environment under any noise condition.

[0005]

In order to achieve the above object, a sound reproducing means provided in a transportation machine such as an automobile,
A microphone for detecting noise in the transportation machine, a first rectifying means for obtaining a first level of a signal detected by the microphone, and a first for obtaining a second level of a reproduced signal output from the sound reproducing means. Two rectifying means, and a gain adjusting means for making the first level substantially equal to the second level,
It is provided with a noise level detecting means composed of an arithmetic circuit for subtracting the second level from the first level, and a volume adjusting means for controlling the volume of the reproduction signal output from the sound reproducing means.

[0006]

Therefore, according to the present invention, the level of the reproduction signal output from the sound reproduction means is reduced from the level of the signal detected by the microphone to obtain the noise level detected by the noise detection means for detecting only the traveling noise. Accordingly, by increasing the volume of the reproduction signal output from the sound reproduction means, it is possible to perform a audible natural volume control corresponding to the actual noise level without depending on the vehicle speed or the engine speed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of an embodiment of the present invention, and this drawing shows a case where it is applied to an on-vehicle audio device. 101 is a sound source such as a tape or a radio,
Reference numeral 102 is a reference signal generator, and 103 is a volume adjusting means.
The volume of the reproduced music signal from 1 is adjusted. Reference numeral 104 is a power amplifier, and 105 is a speaker.
A playback signal is emitted from inside the car. Reference numeral 106 denotes a microphone placed inside the vehicle, and 107 denotes a microphone amplifier that amplifies a signal from the microphone 106. 108, 10
A low-pass filter 9 limits the detection band frequency. Reference numerals 110 and 111 denote rectifying means for obtaining the absolute value (magnitude) of each signal. 11
Reference numeral 2 is a gain adjusting means, 113 is an adder, 114 is a noise level detecting means, and the volume adjusting means 103 is adjusted by a signal from the noise level detecting means 114.

Next, the operation of the above embodiment will be described. In the state where the reproduced music signal from the sound source 101 is not output, the running noise is detected by the microphone 106 placed inside the vehicle, the detection band is limited by the low-pass filter 108 via the microphone amplifier 107, and the rectifying means 110 is used. , The absolute value (magnitude) A of the signal is obtained.

When the reproduced music signal from the sound source 101 is output, the volume is adjusted by the volume adjusting means 103, and is reproduced in the vehicle compartment by the speaker 105 via the power amplifier 104. Also for this reproduced music signal, the output of the volume adjusting means 103 is input to the low-pass filter 109 to limit the detection band, and the rectifying means 11 is used.
At 1, the absolute value (magnitude) B of the signal is obtained. After that, the adder 113 performs processing AB. The volume of the volume adjusting means 103 is adjusted by the gain adjusting means 112 so that A≈B when there is no noise in the passenger compartment. This gain adjustment can be performed even with a normal music signal from the sound source 101, but the reference signal generating means 102 such as white noise is used in order to perform the adjustment with higher accuracy. Note that radio inter-station noise may be used to easily obtain pseudo white noise.

Here, when noise is generated after the adjustment, the actual noise level is obtained by performing the process AB at the adder 113. The result is the noise level detection means 114.
Is averaged for a certain period of time, and the noise level is graded later.
Volume adjusting means 103 according to the stage obtained here.
Is controlled, and the volume of the reproduction signal is increased. In addition, by stipulating the maximum amount of change in a temporally adjacent stage during grading, voice control can be made to act acoustically smoothly.

Further, the rectifying means 110 and 111, the gain adjusting means 112, the adder 113, and the noise level detecting means 11
The processes up to 4 can be digitally processed by a microcomputer or the like.

Further, by providing a high-pass filter circuit before the rectifying means 110 and limiting the frequency band of noise to be detected, the actual noise level can be detected more reliably.

Further, in addition to the volume control according to the detected noise level, the bass range and the treble range are enhanced, so that more comfortable voice control can be performed, and the volume control means 103 can control the volume level. Then, the maximum increase amount of the volume is changed. Further, the noise level detected by the noise level detecting means 114 is averaged at regular intervals, and after grading, the sound volume is increased according to the grading, and the maximum change amount for each graduation is defined. With the configuration in which the stage of increasing the volume is re-determined, the volume adjustment can be made to operate more smoothly in terms of hearing.

[0014]

As is apparent from the above embodiment, the present invention reduces the level of the reproduced signal output from the sound reproducing means from the level of the signal detected by the microphone so that only the level of running noise is detected. Therefore, there is an effect that the volume control corresponding to the actual noise level can be performed without depending on the vehicle speed or the engine speed. Further, since the gain of the signal detected by the microphone is adjusted, even if the sound pressure of the reproduced music signal changes due to the change of the power amplifier or the speaker, it is possible to always detect only the noise level.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a sound reproducing device according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a conventional sound reproducing device.

[Explanation of symbols]

101 sound source 102 reference signal generating means 103 volumes 104 power amplifier 105 speaker 106 microphone 107 microphone amplifier 108 Low-pass filter 109 low pass filter 110 Rectification means 111 Rectification means 112 Gain adjusting means 113 adder 114 Noise level detection means

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-176095 (JP, A) JP-A-5-30588 (JP, A) JP-A-60-263503 (JP, A) 66698 (JP, U) Actual development Sho 55-36620 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04R 3/00 310 H03G 3/20 B60R 11/02

Claims (4)

(57) [Claims] 1. A sound reproducing means, which is provided inside the transportation machine and includes at least a radio, a volume adjusting means for controlling a volume of a reproduction signal outputted from the sound reproducing means, and a microphone for detecting noise in the transportation machine. , First rectifying means for obtaining the level of the signal detected by the microphone, second rectifying means for obtaining the level of the reproduced signal output from the sound reproducing means via the volume adjusting means, and the sound reproducing Using the reproduction signal output from the means, the level obtained by the first rectifying means and the second
The gain adjusting means for adjusting and outputting the level obtained by the rectifying means to be substantially equal when there is no noise, and the level obtained by the second rectifying means is subtracted from the level output from the gain adjusting means. And a noise level detecting means for outputting the calculated result, and when the noise is detected, the gain adjusting means is adjusted by using the inter-station noise output from the radio included in the sound reproducing means when there is no noise. A sound reproducing device characterized in that the volume adjusting means controls the volume of a reproduction signal according to a calculation result outputted by the means. 2. The volume adjusting means is configured to control the noise level.
The calculation result output by the bell detector is stepped after a certain period of time.
Output via the volume adjustment means, depending on the conversion stage.
Control the volume of the reproduced signal that is input and
It is necessary to specify the maximum amount of change in volume according to the above steps.
The sound reproduction device according to claim 1, wherein the sound reproduction device is a sound reproduction device. 3. A sound included in the sound reproducing means when no noise is generated.
While outputting the inter-station noise from Geo,
The level of noise detected by the
The level of the reproduction signal output via the
Adjust so that they are approximately equal, and play the above sound when noise occurs.
Playback signal output from the means via the volume adjusting means
Of the noise detected by the above microphone from the signal level
The volume is adjusted according to the result of subtracting the level.
Sound characterized in that the means controls the volume of the reproduced signal
How to play. 4. The operation result is graded at regular time intervals.
Depending on the stage, it is output via the volume adjusting means.
Control the playback signal volume and
Characterized by defining the maximum amount of change in sound volume according to the stage
The sound reproducing method according to claim 3 .