The role of microphone

The function of microphone is to convert sound signals into electrical signals.

At the beginning of the 20th century, the microphone changed from resistance type to inductance and capacitance type, and gradually developed a large number of new microphone technologies, including aluminum-driven microphone, capacitor microphone and electret microphone, which are widely used at present.

The working principle of loop microphone is that human voice vibrates the diaphragm through air, and then the electromagnetic coil wound on the diaphragm and the magnet around the moving wheat head form a magnetic field for cutting, forming a weak fluctuating current.

The current is sent to the speaker, and then the fluctuating current becomes sound in the opposite process.

Extended data:

Suppression of microphone howling

1. Self-excited howling caused by microphone acoustic feedback is a common phenomenon in karaoke bars. Due to sound feedback, the gain of general public address system can't be very large. The reason of acoustic feedback howling is:

(1) The microphone is too close to the speaker, and the microphone is facing the speaker;

(2) The reverberation adjustment on the mixer is too large;

(3) The microphone volume is adjusted too much;

(4) The pressure limiter is not connected;

(5) Auditorium acoustic design defects.

2. In view of the above reasons, the following measures can be taken:

(1) Define an approximate range for the singer's activity stage, and whistle should not appear in this range. In other words, the singer should not be too close to the main speaker, and the main speaker should be symmetrical on both sides of the stage; A singer should not stand with the microphone pointed at the speaker.

(2) The stage of the karaoke room should be acoustically treated, and sound-absorbing materials should be installed on the walls and sides.

(3) Connect the pressure limiter, and its compression ratio should be set to

(4) Don't turn up the reverberation and volume on the mixer.

(5) When the above measures don't work, we can adjust the equalizer to attenuate the frequency that is prone to howling.

The specific operation method is as follows:

Firstly, the position of each frequency point of the equalizer is recorded; Then, demonstrate it. Increase the volume (adjust with the universal fader of the mixer) until the system just produces self-excitation, and lower the adjustment buttons on the equalizer one by one from the low frequency, which can effectively eliminate the frequency points of self-excitation howling.

According to experience, there is generally only one self-excited resonance frequency (such as 250Hz), which can be pulled down by 3-5 dB, and other frequency points should still keep the original recorded bits.

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