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Homework Help: Superpositon and Standing Waves problem

  1. Feb 6, 2010 #1
    1. The problem statement, all variables and given/known data
    A child has an ear canal that is 1.3 cm long. At what sound frequencies in the audible range will the child have increased hearing sensitivity?


    2. Relevant equations
    for open-closed tube, f= m(v/4L)


    3. The attempt at a solution
    I need two frequencies since the question is asking for a rage in which the child has increased hearing sensitivity. So I thought for an open-closed tube, I could use f= m(v/4L) where m=1 and 3. But my answer does not work. How do I know what nodes (m) to choose? Please help.
     
  2. jcsd
  3. Feb 6, 2010 #2
    I have previously found 6600 and 2.0*10^4 using m=1 and 3, and this range didn't work.
    Could anyone help?
     
  4. Feb 6, 2010 #3
    The question is asking for specific frequecies in the audible range; not a range of frequencies.
    The method is correct. 6600Hz is in the audible range (quarter wavelength). The next resonance should be at 3 times that value. (3/4 wavelength)
    Audible range goes up to 20000Hz typically.
     
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