Arduino/ESP32 Sound Level Meter (SLM) using inexpensive, factory calibrated, digital I2S MEMS microphone and digital IIR filters (vs. FFT) for equalization and A-weighting.

The basic idea is:

And the microphone response after equalization should look like:

Theoretically, i.e. with factory calibrated ICS-4343x, this should get you ±1dB(A) measurement within 20Hz-20KHz range.

The code in this repository is mostly intended as example how you can integrate resonable noise measurement (i.e. L_Aeq, Equivalent Continuous Sound Level) in your projects.

You can find a bit more information in my hackday.io project.