audio feedback

I am not a user of fine sound equipment like manley microphones, but I did recently read this article from Mental Floss about audio feedback, and I think that's pretty interesting. You have to think of sound as a wave. If your microphone gets in the wrong location (in front of the speaker instead of behind the speaker), the sound will become an infinite wave - sound comes out of the speaker, gets picked up by the mic, and gets amplified by the speaker. I don't know music but that appeals to my inner physicist!