JPS6128295A - Output control-type microphone by sound source distance - Google Patents

Abstract

PURPOSE:To reproduce sounds faithful to their original sounds even if the sound source distance is changed by disposing two directional microphone units on the same straight line and correcting an amplitude degree of an amplifier of the microphone closer to the sound source from the difference of frequency characteristics of the microphone unit further from the sound source. CONSTITUTION:Outputs of the 1st and 2nd microphone units 1 and 2 are inputted to a differential amplifier 3 and their outputs are obtained through a low-pass filter 4. Its output can be obtained as a level difference between both microphones 1 and 2 in a low frequency, and the result shows that the larger the output, the closer the microphones to the sound source. The output of the low-pass filter 4 is amplified by an amplifier 5, and gains of a variable gain amplifier 7 are controlled. On the other hand, the output of the 1st microphone unit 1 is amplified by a pre-amplifier 6, and its gains are controlled by the variable amplifier 7, thereby obtaining said output from an output terminal 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microphone whose output is controlled by the distance from a sound source used for speech, singing, etc.

Conventional configuration and its problems 28- Conventional speech or vocal microphones:
The volume is inversely proportional to the distance from the mouth to the microphone, so the output decreases rapidly as you move away from the mouth, and increases rapidly as you get closer. Therefore, in the case of lectures, meetings, singing, etc., changes in the distance between the mouth and the microphone immediately have a significant effect on output fluctuations, resulting in sound quality deterioration and distortion.

This method has drawbacks such as requiring time and effort for level adjustment.

Purpose of the Invention The present invention eliminates the drawbacks of the conventional microphones described above and provides an output control type microphone with excellent sound source distance, in which the output voltage does not show large fluctuations even with changes in the distance to the sound source, especially the mouth. The purpose is to provide

Structure of the Invention In order to achieve the above object, the present invention arranges two directional microphone units on the same straight line, and sets the microphone unit farthest from the sound source to have a standard frequency characteristic. This structure corrects the amplification degree of the amplifier of the microphone unit farther from the sound source due to the difference in frequency characteristics, and has the advantage that the original sound can be faithfully reproduced even if the distance to the sound source changes.

DESCRIPTION OF EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a microphone according to an embodiment of the present invention. In Figure 1, ] is the unidirectional first microphone unit, 2 is the unidirectional second microphone unit, and 2 is the unidirectional second microphone unit.
The microphone unit is the first one. The operation of the embodiment shown in the arrangement described above will be described in which the second microphone units 1 and 2 face in the same direction and are arranged close to each other in the same straight line. A unidirectional microphone unit exhibits changes in frequency characteristics, especially in the low frequency range, depending on the distance from the sound source.

FIG. 2 is a diagram showing changes in the frequency characteristics. That is,
When the microphone unit is close to the sound source, the sound becomes a spherical wave, and the influence of the velocity component appears, so there is a sudden rise from the midrange to the low range, as shown by the dotted line in Figure 2. show. Conversely, as the distance increases, the sound becomes a plane wave, and the influence of the velocity component increases, so the bass range decreases as it approaches the solid line a in the figure. Therefore, the first
The second microphone unit 1 and the second microphone unit 2 have the same characteristics, and both microphones 1 located on the same straight line
, By looking at the difference in the low frequency range of the output of 2, you can know the distance between the microphone and the sound source, and with this distance information,
Microphone output level can be controlled.

In Figure 1, 1. The output of the second microphone unit 1°2 is input to a differential amplifier 3, and its output is obtained through a low-pass filter 4. The output of the low-pass filter 4 is in the low frequency range of both microphones 1 and 2.

The higher the output, the closer the microphone is to the sound source. In other words, the output of the first microphone unit y) 1 that picks up sound has a function of automatically controlling the output sound pressure according to the distance from the sound source.

Effects of the Invention As is clear from the above embodiments, the present invention arranges two directional microphone units on the same straight line, and the difference in frequency characteristics of the microphone unit farther from the sound source is determined by the difference in frequency characteristics of the microphone unit closer to the sound source. This system is designed to correct the amplification degree of the amplifier, and has the advantage of being able to faithfully reproduce the original sound even if the distance to the sound source changes.

[Brief explanation of the drawing]

FIG. 1 shows microphones 6, - according to an embodiment of the present invention.
FIG. 2 is a diagram showing a change in frequency characteristics with respect to distance from a sound source. DESCRIPTION OF SYMBOLS 1... First microphone unit, 2... Second microphone unit, 3... Differential amplifier, 4... Low pass filter, 5... Amplifier, 6... Preamplifier, 7... Variable gain amplifier, 8...output terminal, 9...control signal.

Claims (1)

[Claims] a first microphone unit; a variable gain amplifier that receives a signal from the first microphone unit and changes the degree of amplification depending on the magnitude of a control signal input from a control terminal; A second microphone unit arranged at a predetermined distance on the same straight line, a differential amplifier that detects the difference in input between the first microphone unit and the second microphone unit, and an output signal of the differential amplifier. A microphone of output control type based on sound source distance, comprising a low-pass filter that passes a low frequency portion and outputs the control signal as the control signal.