Real-Time Measurement and Control

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Microphone performance

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I am acquiring unknown sound data for research purposes. I want to make a random check if my microphone is measuring correctly. I have a sound meter that measures SPL in dB. I am not sure how to convert the data I got from the microphone to a sound pressure level (SPL) in dB. The question here is not about the formula to compute SPL (dB) in Pa. My main question is about the relationship between the data acquired and a sound in Pascal (Pa).

Considering the data is in mV, I tried to multiply and divide it at a time by the microphone's sensitivity (in mV/Pa) to compute the SPL (dB in Pa) but the value I am getting does not seem right. I took 0.00002 Pa as a reference.


My data acquisition system comprises the following

  1. Model: 130A23 | ICP® Electret Array Microphone and
  2. NI9234: 4-Channel, 51.2 kS/s/channel, ±5 V, C Series Sound and Vibration Input Module

Looking forward to your help on how to resolve this issue.

Many thanks for your time.


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Accepted by topic author Jaty22

Use this technique,

  • Capture mic waveform
  • Scale the waveform by mic sensitivity
  • Compute RMS
  • Calculate 20log(rms/20u)
  • Now you've dB SPL

If you could share some sample data and mic sensitivity, one can calculate these

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Thanks Santhosh.

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