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Homework Help: Sound intensities in hearing aids

  1. Sep 20, 2014 #1
    What decibel increase does a hearing aid produce if its sound gathering area is 900cm^2, the area of the eardrum is 0.5cm^2, but it only has an efficiency of 5% in transmitting sound to the eardrum?

    I know sound level = 10log(final intensity/initial intensity), but we've only been given areas, so I don't know how to convert these into intensities to find change in sound level?
  2. jcsd
  3. Sep 20, 2014 #2


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    Staff: Mentor

    I think you'll say that the power it collects at the input is transferred across to the output, with an efficiency of 5%.

    Q: How is Power related to Intensity?

    You don't happen to have been given the correct answer? It's always handy ....
  4. Sep 21, 2014 #3
    Thanks solved it turns out I made a mistake on my calculator.
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