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Cross Correlation of two sound signals

  1. Jan 2, 2013 #1
    Hello!
    We are trying to verify if an acoustic standing wave has been established in a cavity. In order to do so, we are giving a constant frequency signal to a speaker. We are picking up the signal at two locations, one very close to the speaker(reference signal) and at a particular location(captured signal). We are cross correlating them. Ideally, we are supposed to get a zero phase difference between the two signals for the frequency sent in, proving that the reference and captured signals are varying simultaneously in time. However, we are getting a jump from -pi to pi at that frequency ?(here,its 520Hz). Could anyone explain what is happening? Thank you for taking your time for this!
     

    Attached Files:

  2. jcsd
  3. Jan 3, 2013 #2

    berkeman

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    Staff: Mentor

    Welcome to the PF.

    Could you also post a diagram of your cavity, showing the speaker location and the locations of the microphones?
     
  4. Jan 3, 2013 #3

    AlephZero

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    Science Advisor
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    Why do you think that should happen? And why do you think it should happen only at a resonance?

    Also, what are you measuring (or calculating) on the plot that looks like an amplitude?

    The sudden change in phase suggests the system has a mode (or resonance) at that frequency, but without a drawing of the complete setup it's hard to guess what is happening.
     
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