How does microphone feedback work?

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How does microphone feedback work?

In: Technology

Basically you feed one sound to the microphone. That sound is sent to the speaker which reproduces it. A part of it is captured by the mic again, and re-amplified. Each time a bit louder. Until the mic, the speaker, the crowd or the sound tech reaches its limit and breaks down.

In the same way the popular university classroom game “say Dick” works.

A bit of sound enters the mic, plays out the speaker which is then picked up by the mic. Oh course the speaker will play that again like an echo almost but feedback does this thousands of times a second-playing the sound and picking back up, repeat.

I cannot explain for certain why the tone climbs to a higher pitch; but I have, for fun, held a mic up to a speaker when it’s really quiet and still seems to happen when close enough.

The microphone is listening to the sound around it. That sound is then played to the speaker. If the microphone can hear what is coming from the speaker, it forms a loop – speaker -> microphone -> speaker -> microphone -> … that is feedback. Technically, positive feedback.

The solution is to make the microphone not hear the speaker – giving you three options.

1. move the speaker further from, or pointing away from the microphone.
2. Reduce the gain on the microphone (it’s sensitivity – so you have to be closer to the mic to be heard.)
3. Reduce the volume of the speaker.