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Relationship between the vibration amplitude and the acoustic radiation

  1. Sep 13, 2011 #1
    Hi ! I need your help !
    I have been kind of stuck with the following problem for a few days :

    I made measurements on a plate radiating sound with an accelerometer and I found very low values of displacement(1-10 pm !). It seems very very very low (less than 1 atom !)
    Depending on the frequency, the sound intensity is more or less 30 dB near the plate (measured at 1cm of distance).

    Does someone have any idea of the typical vibration amplitude of a plate radiating sound ?
    And of the relationship between the vibration amplitude of a plate and the acoustic power radiated ?

    Thanks a lot !
  2. jcsd
  3. Sep 13, 2011 #2


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    I think you made some mistake interpreting the data from the accelerometer.

    One way to answer your question would be to drive a loudspeaker with a sine wave signal (from a signal generator). At fairly low frequencies (say 100 Hz) you will be able to see the motion of the speaker cone, and if you view the speaker with a strobe light you should be able to estimate the amplitude. You will probably find it is of the order of 1mm peak to peak.

    At high frequencies the amplitude will be smaller for the same sound level, but 1pm is orders of magnitude too small.
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