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Homework Help: Speakers in a field/ destructive interferece

  1. Sep 12, 2006 #1
    Imagine you are in an open field where two loudspeakers are set up and connected to the same amplifier so that they emit sound waves in phase at 688 Hz. Take the speed of sound in air to be 344 m/s.

    You are 3.00 m from speaker A directly to your right and 3.50 m from speaker B directly to your left

    What is the shortest distance d you need to walk forward to be at a point where you cannot hear the speakers? D=

    Ok, I've setup a picture that looks something like this

    Speaker A ------- 3.0m --------- Me --------- 3.5 m ----- Speaker B

    Ok, now... I know that I can get perfect destructive interefrence when the path length difference is HALF integer number wavelengths

    so, v = lambda * f = 343 m/s = lambda * 688hz ... lambda =~ .500 m

    so, lamda/2 = .250 m .... That is the shortest distance I know I have to travel in order to have perfect destructive interference.. but I don't know *how/where to* travel to with this distance

    Now I'm cluless as to what I have to do?
    Last edited: Sep 12, 2006
  2. jcsd
  3. Sep 13, 2006 #2
    anybody have any idea?
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