SPL computation, Prms computation

Started by April 9, 2014
Hi I have a microphone(with preamp) connected to a microcontroller - I am able to get samples now, which could be converted to pressure since I have the sensitivity of the microphone. I want to get the sound pressure level.

According to "Engineering Acoustics" and "Engineering Noise Control"(Bies and Hansen), which was referenced by Wikipedia as well

To do this

20 log (pRMS/pRef)

To quote:

where pRef is the reference sound pressure and pRMS is the rms sound pressure being measured.

Does "pRMS" mean that I don't use the "samples-turned-into-pressure" values directly? That I have to get a sequence of the values(discrete time system), get the RMS of that sequence and then use it as an input to the above formula? If so, then how many "samples" should I get in each RMS computation?