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Homework Help: What's the relationship between the amplitude and the Sound power level?

  1. Dec 27, 2011 #1
    Okay, so I have a sound wave (a visual representation). From this I can see the amplitude of the wave, However, I need to know what the sound power or the sound pressure level. Could someone please give me a formula that could help?
    Last edited: Dec 27, 2011
  2. jcsd
  3. Dec 27, 2011 #2

    Simon Bridge

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    You are asking something quite complex and your terms suggest you are not clear about what is going on.

    A sound wave is usually thought of as pressure variations in some fluid like air - though it can also be vibrations in a solid. So the wave itself is the pressure level - though you may have a description of it in terms of longitudinal displacements, in which case you need to translate the displacements into pressure.

    A single note would give you a sinusoid with a constant amplitude. The magnitude of the wave may vary with position and with time for a fixed position.

    The wave can also be represented in terms of energy - the parts where the medium is moving most has the most kinetic energy for example.

    So before you start, you need to know what it is that is being measured.
    A microphone, for example, measures changes in air pressure.

    Possibly what you are looking for is something like this:
  4. Dec 28, 2011 #3
    You're right, I had no idea what I was talking about.
    Thanks for the info, that really cleared things up. That link wasn't exactly what I was looking for, but I understand it all now. I guess all I needed was some sleep. Thanks a bunch anyways.
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