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Entry  Mon Oct 22 20:44:49 2012, Ayaka, Update, Adaptive Filtering, microphone noise mic_noise2.png
    Reply  Tue Oct 23 00:51:41 2012, Jamie, Update, Adaptive Filtering, microphone noise 
       Reply  Tue Oct 23 10:24:42 2012, Ayaka, Update, Adaptive Filtering, microphone noise 
Message ID: 7592     Entry time: Tue Oct 23 00:51:41 2012     In reply to: 7589     Reply to this: 7596
Author: Jamie 
Type: Update 
Category: Adaptive Filtering 
Subject: microphone noise 

Quote:

I will do some experiments on acoustic noise canceling during my stay.
Now I am planning to cancel acoustic noise from PMC and see how the acoustic noise work and how we should place microphones.a

First, I measured the noise in microphones and its circuit.
mic_noise2.png
-blue, green, red, solid lines; microphone signals
-blue, green, red, dashed lines; un-coherent noise in signals
-yellow, black, solid lines; circuit noise (signal input is open, not connected to the microphones)

We can see the acoustic signal above 1 Hz, and the circuit does not seem to limit its sensitivity. But I do not know why yellow and black is so different. I will check it tomorrow.

Hi, Ayaka.  It would be good if you could give a little bit more detail about this plot:

  • What exactly are the "signals"?  Are you making a sound somehow?  If so, what is producing the sound?  What is it's spectrum?
  • Are the blue/green/red traces from three different microphones?
  • Coherence usually implies a comparison between two signals.  Is something being compared in the dashed traces?
  • Are the yellow and black traces from different amplifiers?
  • What are the units of the Y axis?

 

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