Setting up this simple microphone. Connect to 5v, ground, A0. Rotated screw counter clockwise until L2 light turned off. Snapped fingers, L2 light will not light back up with sound. Serial monitor at steady 49dB, no change. adjusted screw so light was flickering, just on the margin of connecting, , still no reaction to noise. Faulty hardware?
It probably won't pick-up finger snapping. I have a different sound sensor and there is a lot of electrical noise from the preamp on the board so the sound has to be a little loud. For example, I have to turn-up my TV louder than I normally listen before it puts-out a signal higher than the noise.
In works a little better (I can read quieter sounds) when I power the Arduino from a power supply instead of USB. USB-power is notoriously (electrically) noisy and you have to leave it connected to use the Serial Monitor but the external power supply seems to "dominate". The noise is not an issue with digital, but microphones put-out a tiny signal so they use a preamp with a gain of around 100-1000 and any noise gets amplified along with the signal.
And the Arduino isn't reading the analog input continuously. It's reading for one instant every time through the loop and it might miss a finger-snap or hand-clap.
Similarly, the LED built-into the board might take a little more time before it comes-on or before you can see it, but that's not limited by software.
Have you tried shouting directly in the mic or some other loud sound?
This page says:
You didn't show us your code but 49dB SPL is around the background noise in a home, and I assume you didn't calibrate your code with a real SPL meter. But it could be electrical noise and you can't read below that.
SPL Chart. (It says a normal home is about 50dB SPL.)
Update: I got a new KY-037 sound detector and hooked up to the same cables and it works perfectly. Detecting snaps and all. I conclude it was faulty hardware.
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