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Homework Help: Finding the amplitude of a pressure wave

  1. Jul 4, 2011 #1
    1. The problem statement, all variables and given/known data
    The sound level in decibels is typically expressed as β = 10 log(I/I0), but since sound is a pressure wave, the sound level can be expressed in terms of a pressure difference. Intensity depends on the amplitude squared, so the expression is β = 20 log(P/P0), where P0 is the smallest pressure difference noticeable by the ear: P0 = 2. 10-5 Pa. A loud rock concert has a sound level of 106 dB, find the amplitude of the pressure wave generated by this concert.

    2. Relevant equations

    3. The attempt at a solution
    I'm not really sure what this question is asking. It seems to be it's asking for the pressure amplitude? Is that correct?
    If that's the case, I plugged all the numbers in and solver for p_0, but that's not right. So I guess the question I should be asking is how do I find the amplitude of a pressure wave?

    I learn through examples, and I'm absolutely willing to try. This problem is from my last homework assignment (meaning it won't help my grade), I'd just like to learn how to do it. Can someone give me a nudge in the right direction?
  2. jcsd
  3. Jul 4, 2011 #2


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    Homework Helper


    The question gives you p_0: it's 2*10^-5 Pa. That's the smallest pressure amplitude the ear is sensitive to. You're trying to find P, knowing β and P0, in β = 20 log(P/P0).
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