What audio phenomenon occurs when a loop exists between a speaker and the microphone attached to it?

The audio phenomenon that happens when a loop exists between a speaker and the microphone is known as feedback. This occurs when sound from the speaker is picked up by the microphone, amplified, and played back through the speaker again, creating a loop. As this cycle continues, the sound builds in volume, often resulting in a high-pitched screech or hum that can be disruptive and unpleasant.

Feedback is a common concern in live sound situations and recording environments, as it can quickly escalate and disrupt a performance or a recording. Understanding feedback is crucial for sound engineers and technicians to manage audio levels and prevent unwanted noise during a production.