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I am working on a project where I am using a Arduino Nano to count number of Loud Sound (occurring at intervals) with intensity between 65 dB - 100 dB. I want to put a calibration unit and a digital display unit to calibrate the device within the aforesaid range and display the total count.

I am little bit concerned about the heart of the circuit - the sound sensor. I am thinking of a Electret Mic. Is it a good component to measure Loud Sound Level uniformly? I mean if I employ a electret mic to capture sound and place the output to an amplifier to measure the output analog signal, would it produce same analog reading (with minimum tolerance) for similar intensity of sound everytime? To further clarify it - when a sound is heard with 70dB intensity, if my arduino reads 95 from the sound sensor circuit, would it read something close to 95 everytime 75dB sound is produced?

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  • \$\begingroup\$ What does the datasheet say? \$\endgroup\$
    – Majenko
    Commented Aug 29, 2016 at 19:31
  • \$\begingroup\$ Do you care about the sound frequency? \$\endgroup\$ Commented Aug 29, 2016 at 19:31
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    \$\begingroup\$ ni.com/white-paper/14349/en \$\endgroup\$ Commented Aug 29, 2016 at 19:32
  • \$\begingroup\$ @RogerRowland Nope, I don't. \$\endgroup\$
    – sribasu
    Commented Aug 29, 2016 at 19:33
  • \$\begingroup\$ @Majenko Actually that's a good idea. I didn't see that data in datasheet. May be worth taking a look. \$\endgroup\$
    – sribasu
    Commented Aug 29, 2016 at 19:33

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It may be repeatable but not very accurate compared to B&K sound pressure monitor in an anechoic chamber.

Electret mics usually have an open back for far field cancellation,,so they are designed for near field sounds. They are not acoustically flat and thus may generate a poor comparison with different frequency sources.

But for your purpose for linearity, it may be ok, if you are not too loud or too close.

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  • \$\begingroup\$ Actually the sound will be produced by explosion at a distance. The device is expected to capture sound from open air/area. The range is as said - 65dB - 100dB \$\endgroup\$
    – sribasu
    Commented Aug 29, 2016 at 19:55
  • \$\begingroup\$ Is there any reason the sound pressure meter must be B&K? \$\endgroup\$
    – JYelton
    Commented Aug 29, 2016 at 20:49
  • \$\begingroup\$ NO . but I can vouch for Bruel and K ,,having used them \$\endgroup\$ Commented Aug 29, 2016 at 20:52
  • \$\begingroup\$ @sribasu Detonation sounds are very wide frequency range and the device must suit the accuracy needed for high impulse sounds. Accurate Testing will validate your design \$\endgroup\$ Commented Aug 29, 2016 at 20:57
  • \$\begingroup\$ I think you mean Brüel & Kjær as opposed to B&K Precision? Both manufacture sound pressure meters. Anyway, I just think it's unusual to cite a particular brand unless it is is pertinent. \$\endgroup\$
    – JYelton
    Commented Aug 29, 2016 at 22:32
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Electret itself may be fine. But you have to calibrate it. Also you must have very nice circuit around the microphone to provide stable bias. Last, remember that like any microphone, electret, together with your acoustic system has frequency reaponse. So you will have to apply some correction to any reading you have.

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