Feedback is a phenomenon that occurs when a microphone picks up sound from a speaker while that speaker is playing sound from the microphone, thus creating a loop. It is commonly described as a signal feeding back into itself. Feedback commonly occurs during live performances or wherever there are speakers broadcasting nearby microphones.

How it works

In short, feedback is a loop of sound. When a microphone is capturing sound and the signal from that microphone is played through a speaker system near the microphone, feedback may occur because there is a loop being created. The speaker is playing what the microphone is picking up and the microphone is picking up what the speaker is playing.

Feedback is dependent on the following:
A) The sensitivity of the microphone
B) The loudness of the speaker
C) The distance between the speaker and the microphone

The microphone is intended to capture the sound waves of something close by, such as a person's voice or an instrument. When the microphone captures the sound, the signal is routed through a cable into a device to process the signal, amplify it, and then play it through a speaker, thus making that voice or instrument sound much louder. Where the feedback occurs is when the speaker is creating sound waves that reach the microphone and the loop is created.

The feedback sound occurs when the volume of the microphone signal playing through the speaker reaches a threshold where it begins playing the microphone signal louder each time it passes through the loop. The speaker is amplifying the microphones signal so if the microphone is too close to a speaker that is amplifying that same signal, the microphone will capture its own signal in real-time and amplify the signal louder and louder every time it passes through the speaker. The signal begins to grow in volume and quickly causes a feedback loop. The sound of feedback is typically a very high frequency or pitch, and is usually very loud.