JPS62171300A - Noise compensation device for acoustic equipment - Google Patents

Abstract

PURPOSE:To listen to a sound signal without causing the feeling of disorder even under the environment causing a low frequency noise and to compensate the noise by generating the 2nd order or over of harmonics of the low frequency sound signal in which noise is distributed and adding the original sound signal. CONSTITUTION:The sound signal from a sound source 1 being an on-vehicle acoustic equipment is transduced into sound by a speaker 6 through an adder circuit 3 and an amplifier circuit 5. On the other hand, a sound signal from the sound source 1 is given to a low pass filter 7 filtering and extracting the sound signal below 100Hz and the output of the low pass filter 7 is given to a harmonizer 8 forming the 2nd order harmonic of the inputted sound signal. The 2nd order harmonic signal from the harmonizer 8 is given to an amplifier circuit 9 whose amplification factor is varied, where the signal is amplified and given to an adder circuit 3. A car speed detection means 11 gives a pulse signal corresponding to the speed of automobile to the amplifier circuit 9. The signal varies the amplification factor of the amplifier circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a noise compensation device for audio equipment for compensating for the so-called masking of the low frequency range of an audio signal from an audio source being added to the noise.

BACKGROUND ART For example, in a sound system installed in a car, the low frequency range of music, which is an audio signal from a sound system, is masked by +71 room noise. *The noise in the room is, for example, less than 100 Hz (range 1).

Problems to be Solved by the Invention In order to compensate for the masking in the low frequency range of music caused by various noises, the volume has conventionally been increased over the entire audible frequency range. Therefore, the listeners in the lit room experience a sense of strangeness in their hearing. Additionally, increasing the volume to compensate for the masking caused by such low-frequency noise requires a high-output amplification circuit to amplify the audio signal, and also requires a large-diameter speaker capable of outputting low-frequency sounds. .

Is the purpose of the present invention low-frequency @sound? It is an object of the present invention to provide a noise compensation system for audio equipment that can achieve noise compensation without causing discomfort and without requiring a high-output amplification circuit or a large-diameter speaker. .

The present invention provides a low-pass filter that converts the low frequency range of audio No. 13 from an acoustic source into a P wave, a monetizer that generates a double overtone of the output from the low-pass filter, and a harmonizer. This is a noise compensation system for audio equipment, characterized in that it includes a 1,000-ft.

In terms of function and hearing, even if the fundamental frequency cannot be heard, the frequency of two or more frequencies can be heard.
By listening to overtones with frequencies that are several times higher than the fundamental frequency, you will feel the same way as when you hear the fundamental frequency. In the present invention, paying attention to this point, the low frequency range of the audio signal from the acoustic source is extracted as a t-wave using a low-pass filter, and the second overtone of the low frequency range is created using a harmonizer and added to the audio signal from the acoustic source. This results in a low range of 9! This prevents the low frequency range of the audio signal from being masked by the WJ sound in an environment where public noise is generated. For example, the low frequency noise in the cabin of your car is 10
0Hz$, full.

@Improve the sound distribution (If you create 3 or more overtones of the audio signal in one range and add them to the original audio signal, the noise compensation effect will be lost, and the audio signal will become distorted and difficult to hear.)

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. The audio signal of the car chant = q m and the voice of the instrument (si 1 or ζ) is fed from line 2 to the adder circuit 3 . The audio signal derived from the adder circuit 3 to the line 4 is amplified by the amplifier circuit 5 and converted into sound by the speaker G.

The audio signal derived from the sound Ny source 1 to line 2 is also
It is applied to a low-pass filter that extracts audio signals of less than 100 Hz as T-waves. The output from the low-pass filter 7 is sent to a harmonizer 8 that creates the second harmonic of the input audio signal.
given to. The second harmonic audio signal from the harmonizer 8 is applied to an amplifier circuit 9 with a variable amplification factor, where it is amplified, and then applied from a line 10 to the adder circuit 3.

A vehicle speed detection means 11 for detecting the vehicle speed of an automobile sends a pulse signal corresponding to the vehicle speed to the processing circuit 1 via a line 12.
Give to 3. The processing circuit 13 is realized by, for example, a microcomputer, and outputs an analog signal corresponding to the vehicle speed to the line 4 and supplies it to the amplifier 11 circuit 9. The amplification factor of the amplifier circuit 9 is changed by the signal from the line 14.

FIG. 2 is a block diagram showing a specific configuration of the harmonizer 8. The audio signal from the bass filter 7 is
Bypass filter 15 that converts audio signals of 0Hz or higher into P waves
given to. The appearance from bypass fill 15 is 5
Is the audio signal less than 0H? A low pass filter is provided.

In this 1), the bypass filter 15 and the low-pass filter 16 work together to function as a band-pass filter that filters the audio No. 43 of 20 to 50H7.The output from the low-pass filter 16 is a full-wave The signal is applied to the rectifier circuit 17 and its waveform is distorted. Aftermath rectifier circuit 17
The output from is provided to a low pass filter 18 that filters out audio signals below 150 Hz. In this way, the full-wave rectifier circuit 17 derives harmonics that are two or more natural number times of the audio signal derived from the low-pass filter 16, and the low-pass filter 18 extracts only the second harmonic of those harmonics. It is led out to line 19 and sent to mixing circuit 20 with four elements.

Furthermore, the audio signal from the low-pass filter 7 is applied to a bypass filter 21 that converts audio signals of 50 Hz or higher into P waves. The output from this bypass filter 21 is 100
A low pass filter 22 is provided which filters audio signals below Hz. Bypass filter 21 in this L manner,
The low-pass filter 22 functions as a band-pass filter that converts audio signals of 50 to 100 H7 into P waves.

The output from the low-pass filter 22 is transmitted to a full-wave rectifier circuit 23.
The sound is distorted by the sound, and overtones of natural number multiples of 2 or more are heard. The output from the full-wave rectifier circuit 23 is given to a low-pass filter 24 that converts audio No. 43 of less than 2 (1082) into a P wave, whereby only the second harmonic of the audio signal from the low-pass filter 22 is extracted and sent to the line. 25 to the mixing circuit 20 (given 2. The output from the iR circuit 20 is given to the amplifier circuit 9). I'll give you one shot.

The noise level within 11'7 increases as the vehicle speed increases, as shown in FIG. Therefore, the processing circuit 13 controls the amplification circuit 9 so that as the vehicle speed increases, the amplification factor or gain of the amplification circuit 9 increases as shown in FIG. Therefore, regardless of the increase in J'11 jg, the noise level inside the vehicle increases, and at this time, the low-frequency second overtone of the audio signal produced by the bar monaizer 8 is also increased, so that WJ! The low range M compensation corresponding to the 0 level is suppressed, thereby preventing the low range of the sound 7tf signal from being masked by noise. Therefore, the listener inside the vehicle can listen to the audio signal without feeling uncomfortable. Further, according to this embodiment, there is no need for a high-output amplification circuit as described in connection with the previous embodiment, and there is no need to amplify the low-frequency audio signal. Does not require speakers.

In the above-mentioned embodiment, by changing the amplification factor of the amplification circuit 9 for the low-frequency audio signal in accordance with the noise level in the vehicle interior, the two-tone sound is added to the original sound signal. However, as an embodiment of the present invention, instead of the vehicle speed detecting means 11, a microphone for determining the noise level in the vehicle interior may be used; The noise inside the vehicle is indirectly detected from the tachometer of the μ-frame output stage internal combustion engine and the means for detecting the opening of the window in the claw chamber, and the noise is amplified by the amplifier circuit 9. The rate may be varied or increased.

Effects As described above, according to the present invention, it is possible to listen to audio signals without causing discomfort in an environment where low-frequency noise is generated, and also achieves the advantages described in relation to the prior art described above. It becomes possible to compensate for noise without requiring a high-output amplification circuit or a large-diameter speaker.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram of an embodiment of the present invention, and FIG.
:'71 is a program showing the specific configuration of harmonizer 8. Figure 3 shows the sound level inside the nail chamber.
FIG. 4 is a graph 62 for explaining the function of the processing circuit 13. DESCRIPTION OF SYMBOLS 1... Sound source, 3... Adding circuit, 5.9... Amplifying circuit, G... Speaker, 7... Low pass filter,
8...Harmonizer, 11...Vehicle speed detection means, 13
...Processing circuit formula J″I!k Patent attorney Kei Nishikyo
・Part 3 Figure 0 Table humidity

Claims (1)

[Claims] A low-pass filter that filters the low frequency range of an audio signal from an acoustic source, a harmonizer that produces a double overtone of the output from the low-pass filter, and means for adding the output from the harmonizer to the audio signal from the acoustic source. A noise compensation device for audio equipment, characterized by comprising: