Welcome to brain Stuff from how stuff Works dot com where smart happens. Join Josh and Chuck, the guys who bring you stuff you should know, as they take a trip around the world to help you get smarter in a topsy TRV economy. Check out the all new super Stuff Guide to the Economy from how Stuff Works dot Com, available now exclusively on iTunes. Hi. I'm Marshall Brain with today's question, what causes that howling sound in p A systems? A simple p A or public address system consists of
a microphone and amplifier and one or more speakers. Whenever you have those three components, you have the potential for feedback. Feedback occurs when the sound from the speakers makes it back into the microphone and is re amplified and sent through the speakers. Again. Imagine that you place the microphone in front of a speaker. Now you tap on the microphone. The sound of that tap is through the amplifier, comes out the speaker, and it re enters the microphone. That
cycle repeats over and over. This loop happens so quickly that it creates its own frequency, which we hear as a howling sound. The distance between the mic and the speaker has a lot to do with the frequency of the howling, because that distance controls how quickly the sound can loop through the system. If you're setting up a sound system and you want to avoid feedback, there are a few general rules that can help you avoid the problem. First, make sure the speakers are in front of the microphone
and pointing away from the microphone. If the speakers are behind the microphone, then feedback is nearly guaranteed. Second, use a unidirectional microphone. Third, place the microphone close to the person who's speaking or performing, And fourth, if you have access to an equalizer, dampen the frequencies where feedback is occurring. Do you have any ideas or suggestions for this podcast us? If so, please send me an email at podcast at
how stuff works dot com. For more on this and thousands of other topics, go to how stuff works dot com. M HM