Microphone self noise

Discussion in 'The Projects Forum' started by mhe, Mar 2, 2012.

  1. mhe

    Thread Starter New Member

    Aug 10, 2011
    10
    0
    Hi

    I have a microphone with sensitivity performance of 40dB at 1kHz.
    The signal to noise ratio is 60dB

    I have found that 60dB signal to noise ratio correspond to 94-60 = 34dB selfnoise.

    Can someone tell me how much self noise I should expect in VOLT based on these two parameters, if I measure in an silent environment.


    Datasheet for the microphone.
    http://www.google.com/url?sa=t&rct=...gfvyZDwrwO67QH92Q&sig2=OO_4eDahUPaI8yNANuwvwQ

    Thanks...
     
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  2. mhe

    Thread Starter New Member

    Aug 10, 2011
    10
    0
    Hi again

    Think I got the answer

    At 94dB = 1Pa the microphone produces 10mV and hence 10mV/Pa

    Since the self-noise at 34dB correspond to 0.001Pa, the microphone produces 10microVolt noise when placed in a silent environment.
     
  3. mhe

    Thread Starter New Member

    Aug 10, 2011
    10
    0
    Hi

    I am trying to calculate the noise contribution from a microphone.

    In the datasheet the following information are reported.
    Sensitivity : -40dB at 1kHz.
    S/N Ratio : 60dB.

    -- My Calculation ----
    NoiseFloor = 94dB - 60dB = 34[dB]
    Sensitivity = 10^(-40/20) = 10[mV/Pa] or 10[mV/N/m^2]

    NoiseFloor in Pa = 10^(NoiseFloor/20) Po = 10^(34/20)*2*10^-5 = 0.001 [Pa];
    NoiseFloor in mVolt = Sensitivity * NoiseFloor = 10*0.001 = 0.01 [mV]

    *Po: In pure silence there is a constant pressure-atmospheric pressure Po.

    Is this calculation correct ?

    Thanks
    Regards Mads
     
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