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Homework Help: Sound attenuation

  1. Sep 24, 2007 #1
    Sound attenuation

    for my physics project I decided to investigate sound attenuation effect, for my equipment I’m using a speaker with a signal generator and at the other end a microphone with an oscilloscope...the sound generator and receiver were placed inside a tube which was well insulated to prevent the apparatus resonance(but i still get a resonance effect and I don’t know if it will affect my results)...also the apparatus is designed so I could insert different materials and different thicknesses in between the receiver and speaker

    I was wondering if anyone could answer the following questions.

    1. to show my results in dB i must find the sound intensity in W/m^-2...is it the same as the peak to peak voltage readings in my oscilloscope

    2. What type of materials should I be looking for that can be easily accessible?
    I was thinking of polystyrene, also what properties in a material make it good for sound insulation?

    3. To plot graphs I was thinking of using the equation lnI= lnIo - μx where μ is the materials coefficient of attenuation and x is the thickness of the insulation....for the graph I was advised to vary x keeping the frequency constant but I don’t really know what frequency I will chose since humans have can hear a really big range of frequencies.. will the second graph for the same material vary μ as I change frequency

    if u have any suggestions for any other experiment suggesting sound attenuation ill be glad to hear it

  2. jcsd
  3. Sep 24, 2007 #2


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    Staff Emeritus
    Science Advisor

    One could try a metal bar, a wooden rod, and polystyrene foam or polyethylene.

    One could also try different frequencies of low, med and high in the range of human hearing to see what the difference, if any, in attentuation might be.

    Sound proofing tends to be soft material vs hard material.
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