-1

I' m using digital microphone (MEMS) on STM32 discovery board Fto record ambiant noise, and I need to know how to convert the samples amplitude to power level in dB SPL.

the microphone that I 'm using is the MP45DT02, in the datasheet the sensibility of the mic is -26 dBFS and the SNR is 61 dB

bytecode77
  • 14,163
  • 30
  • 110
  • 141
Mondher Ben
  • 1
  • 2

1 Answers1

0

What the senstivity means is that a 94 dBSPL sine input will give a -26dBFS peak output level, or a -29 dBFS rms output level. Unless your signal is a sine wave it's probably makes more sense to use rms.

  1. Measure the RMS of the signal.
  2. Convert the RMS value to dBFS (dBFS = 20*log10(rms)))
  3. Convert the dBFS value to dBSPL using the relationship of -29 dBFS = 94 dBSPL. For example, if you measured -50 dBFS then you are 21 dB down from -29. 94-21 = 83 dBSPL and there's your answer.
jaket
  • 9,140
  • 2
  • 25
  • 44
  • I understood the relationship between dBFS and dBSPL using the sencibility when i read the article below, [link] (http://www.analog.com/library/analogDialogue/archives/46-05/understanding_microphone_sensitivity.html) – Mondher Ben Jul 03 '15 at 08:37