I have a circuit with a MEMS microphone and would like to be able to measure the audio noise spike contents and check the noise floor power level in the audio circuit.

My intention is to connect the oscilloscope to the MEMS microphone but before that I would like to know the procedure to analyse the signal shown in the oscilloscope. This is, do measurements need to be done in specific ambient control? Is it necessary to use a specific audio signal for the MEMS microphone to receive and transduce?

On the other hand, maybe using audio fft analysis tools could help. Is there a free one that can be use for this purpose?

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    \$\begingroup\$ Have you compared the scope noise floor specs with the expected voltage levels of the mic noise? \$\endgroup\$ – PlasmaHH Oct 23 '18 at 11:43
  • \$\begingroup\$ So basically I should measure the MEM mic output noise in the oscilloscope and compare it to the datasheet specs? \$\endgroup\$ – user6127833 Oct 23 '18 at 11:49
  • \$\begingroup\$ What exactly are your trying to measure? A microphone, by definition, will convert the ambient acoustical noise into electrical noise. Determining the amount of noise contributed by the microphone itself is not a trivial exercise. \$\endgroup\$ – Dave Tweed Oct 23 '18 at 13:24
  • \$\begingroup\$ Yes, I understand, that´s why I am asking...I would like to measure the idle noise in the ciurcuit right after the MEM microphone. The circuit has a filter after the microphone so I would also like to measure it after the filter and compare both values. I don´t know if this is possible (w/o an anechoic chamber) nor how to do it \$\endgroup\$ – user6127833 Oct 23 '18 at 13:31
  • \$\begingroup\$ In that case, you want to disconnect the microphone and replace it with a resistor that represents its source impedance. \$\endgroup\$ – Dave Tweed Oct 23 '18 at 13:33

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