I would like to measure the SNR of a microphone with the same method applied by the main manufacturers, that is displayed in their datasheets (example here with Neumann's U87 technical spec):
Here is how I plan to do it:
Play a continuous 1 kHz sine signal with a studio monitor loudspeaker (ideally in an anechoic room)
Adjust the playback volume such that the measured volume, close to the microphone, is 94 dB SPL, by using a sound level SPL meter device
Question here: should it be 94 dB SPL RMS or peak? (For a sine there's a difference of ~ 3 dB between RMS and peak)
Record the audio signal with a digital audio interface
Stop the playback of the sine and also record some silence (and thus some microphone noise: that is precisely what we want to measure!)
Normalize the recorded WAV file to 0 dB FS (so this will take the peak of the signal in consideration)
Is this step correct? It seems that a normalization is required here; if no normalization is done, the result SNR would depend on the preamp input gain!
Compute the RMS of the A-weighted signal, during the silence/noise-only part.
This will be the final "Signal-to-noise ratio, A-weighted (re. 94 dB SPL) of the microphone".
Is this correct?
Here is a WAV file I recorded with the method described here. I'm curious to find how to find the A-weighted SNR of this microphone.