Speaker 1: Welcome to brain Stuff from how stuff Works dot com
Speaker 1: where smart happens. Join Josh and Chuck, the guys who
Speaker 1: bring you stuff you should know, as they take a
Speaker 1: trip around the world to help you get smarter in
Speaker 1: a topsy TRV economy. Check out the all new super
Speaker 1: Stuff Guide to the Economy from how Stuff Works dot Com,
Speaker 1: available now exclusively on iTunes. Hi. I'm Marshall Brain with
Speaker 1: today's question, what causes that howling sound in p A systems?
Speaker 1: A simple p A or public address system consists of
Speaker 1: a microphone and amplifier and one or more speakers. Whenever
Speaker 1: you have those three components, you have the potential for feedback.
Speaker 1: Feedback occurs when the sound from the speakers makes it
Speaker 1: back into the microphone and is re amplified and sent
Speaker 1: through the speakers. Again. Imagine that you place the microphone
Speaker 1: in front of a speaker. Now you tap on the microphone.
Speaker 1: The sound of that tap is through the amplifier, comes
Speaker 1: out the speaker, and it re enters the microphone. That
Speaker 1: cycle repeats over and over. This loop happens so quickly
Speaker 1: that it creates its own frequency, which we hear as
Speaker 1: a howling sound. The distance between the mic and the
Speaker 1: speaker has a lot to do with the frequency of
Speaker 1: the howling, because that distance controls how quickly the sound
Speaker 1: can loop through the system. If you're setting up a
Speaker 1: sound system and you want to avoid feedback, there are
Speaker 1: a few general rules that can help you avoid the problem. First,
Speaker 1: make sure the speakers are in front of the microphone
Speaker 1: and pointing away from the microphone. If the speakers are
Speaker 1: behind the microphone, then feedback is nearly guaranteed. Second, use
Speaker 1: a unidirectional microphone. Third, place the microphone close to the
Speaker 1: person who's speaking or performing, And fourth, if you have
Speaker 1: access to an equalizer, dampen the frequencies where feedback is occurring.
Speaker 1: Do you have any ideas or suggestions for this podcast us?
Speaker 1: If so, please send me an email at podcast at
Speaker 1: how stuff works dot com. For more on this and
Speaker 1: thousands of other topics, go to how stuff works dot com.
Speaker 1: M HM