Why does the microphone make a screeching noise when it is facing the speaker?

That noise is called whistling.

sound, especially when the microphone is facing the speaker.

In the sound system, this is due to the formation of positive feedback at this time.

Caused by loop: after the signal of the microphone is amplified by the power amplifier, it is connected to the horn, and the speaker emits the sound of the microphone; The microphone receives the "microphone" sound from the horn and then amplifies the signal through the power amplifier, and then receives the horn, and the speaker emits the sound of the microphone. In this cycle, the sound of the microphone is constantly amplified, which causes a whistling sound.

This whistling sound is easy to burn and affect the tweeter in the speaker, so the tweeter** will be installed in the speaker to prevent the tweeter from burning out.

This whistling sound is also related to the type of microphone, and in order to reduce this phenomenon, a "cardioid" or "supercardioid" microphone should be used to block out ambient noise as much as possible.

In addition, it is also related to the placement of speakers, and the speaker placement should not be facing the microphone as much as possible. Take the stage as an example, try to face the audience as much as possible, not the center of the stage where the microphone is used.

This noise is called "howling" and is a type of echo sound.

This noise is called "howling" and is a type of echo sound.

First, let's talk about what a retrospective sound is. Feedback sound is the sound produced by the microphone is amplified by the power amplifier and sent to the speaker, and then detected by the microphone and then sent to the power amplifier to amplify, and then sent to the volume and so on, that is, the feedback tone, if the high-frequency component.

If there are too many words, the consequence is a harsh squeak, and if the low-frequency components are too large, the consequence is a very low hum... sounds.

2. If the howling continues, the speaker system will be burned at the least, and the speaker amplifier will be burned out at worst.

Seeing this, you can see why Mike is prone to "howling" at the stereo.

3. Because the microphone is mostly directional to collect sound, when the microphone is facing the audio, the noise in the sound will be re-collected by the microphone, then amplified, and then collected by the microphone, and then it will enter this vicious circle.

4. There are many ways to avoid "howling", in addition to not letting the microphone face the sound and placing the microphone on the back of the sound radiation direction, the microphone is as close as possible to the sound source and the use of non-directional microphone is also one of the most effective ways to avoid "howling" and improve the volume of sound amplification.

This is because the sound forms a circular loop between the microphone, the amplifier and the speaker, so that the sound becomes infinitely amplified, so the amplifier will cause self-excitation, and the speaker will emit a piercing whistling, this phenomenon is like a short circuit in the wire, it is easy to burn the amplifier or speaker, so this situation must be avoided. To prevent this, 1, you can turn the volume down a little. 2. Distance the microphone and speaker a little.

3. Avoid the microphone directly facing the speaker.

The reason why the microphone is too close to the speaker is that when a closed "loop" is formed between the microphone and the speaker of the speaker, an acoustic feedback phenomenon is generated, which will produce a high-pitched strange sound, which is a relatively common phenomenon.

Acoustic feedback is the phenomenon of transmitting the sound emitted by the speaker of the speaker to the microphone, and then amplifying it through the speaker. In this cycle, the sound emitted by the speaker will become louder and louder, until the sound can no longer be amplified and saturated. In order to reduce the number of screeching noises, you can use the equalizer to adjust the amplification of the signal.

1. You can lower the volume of the microphone, reduce the sensitivity of the microphone, and adjust the total volume on the speaker, so that the microphone will not make a sharp strange sound if it is too close to the speaker.

2. Keep a certain distance from the speaker when using the microphone, do not face the speaker at close range, and do not face the speaker of the speaker, so as to reduce the frequency of sharp and strange sounds.

In a sound system, the microphone is the input and the speaker is the output. The normal signal is transmitted from the microphone to the sound after being amplified by the circuit system, which is called forward feeding, and there is no problem.

If the microphone is pointed at the speaker, the sound branch box through the air medium to the microphone will form a signal channel, this channel is called the feedback channel, the forward feed and the feedback channel together form a signal "closed circle", which is not allowed.

Due to the formation of this closed loop, the signal will be strengthened at a certain frequency point, resulting in a self-excited whistle (self-oscillation), which is called positive feedback (positive feedback), so the loudspeaker will emit a very loud sound of that frequency, and in severe cases, the speaker will be burned.

In practice, there are many types of echo tones. The "howling" we hear most often is also one. But what we're looking for is the kind of feedback that can control volume, timing, pitch, and even timbre.

"Howling" is uncontrollable. It's been a long journey from uncontrollable acoustic noise to controllable feedback.

There are many ways to avoid "howling", in addition to not letting the microphone sound at the sound and placing the microphone on the back of the direction of the sound radiation, the microphone as close to the sound source as possible and using a non-directional microphone is also one of the most effective ways to avoid "howling" and increase the volume of the sound.

The screeching sound emitted by this sound is commonly known as "howling". The reason for this is the "circuit feedback" generated between microphone speakers, which is a common physical phenomenon. It will often be encountered in conference rooms and stage debugging, and it can be solved after adjusting the distance between the microphone and the speaker and the monitoring volume.

The way to avoid whistling is to:

1. Use monitor headphones when singing, anchoring, tuning, and recording songs on the Internet, don't use speakers; Turn off the microphone and turn on the speaker when watching movies and listening to **.

2. When engaging in family KTV, the microphone and speaker are used together, and the distance, angle and volume of the microphone and the speaker should be adjusted to avoid howling. If there is no uniformity in adjusting the distance and volume, adjust it according to the equipment and room conditions.