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Sound waves

  1. Feb 3, 2005 #1
    I got this wrong on a midterm, i have NO IDea absolutely how to solve this type of problem. I asked my TA too and he has no idea

    -An observer hears the 343 Hz sound produced by two speakers. One is 5m from him, the other is at a distance L the first and can be moved. Taking the speed of sound to be v=343 m/s, for what values of L will the observer hear an increase in volume? (assume the speaker can only move to the right of the fixed one and that the amplitude of the waves does not decrease with distance)

    the right answer is 0, 1m, 2m, 3m....

    anyone have any idea why?

  2. jcsd
  3. Feb 4, 2005 #2


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    Science Advisor

    The speed of sound is 343 m/s, so the wavelength at 343 Hz is 1 m. So 2 in-phase speakers will reinforce the signal at distances of n times 1 m apart. If you still don't get it, draw yourself a picture. P.S. Get another TA.
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