Why does bringing a mic near a speaker cause feedback?

[Antoneo]

Is it because the oscillations that are coming from the microphone become amplified again and again as it comes closer to the speaker?

 

[Talon]

The microphone picks up the waves coming from the speakers and feeds it back into the system, causing it to stack up on itself. Proper microphone selection (pattern type), volume settings and placement of the microphone and the speakers in relation to each other can eliminate the problem.

 

[Magicthyse]

No, the little men who work the speakers have a pathological fear of microphones.

 

[4824guy]

<< Is it because the oscillations that are coming from the microphone become amplified again and again as it comes closer to the speaker? >>



Feedback can do this also, depending on the room and amplifier setup, it can start off as just a short feedback ring or burst or can be very long in duration.