Feasibility ESP32 with sound.

[PatLub85]

Hi,
I have a machine that rings when it has finished its work, but I can't hear it because it is at the end of my house. I have some ESP32 in my drawer, and I wondered if it would not be possible:
-1: record the ringtone (with INMP441?) and store this file (wav?)
-2: listen to the ambient noises, and compare with this file (how?).
-3: if the comparison is established, send a notification
Do you think this is possible and if so, with what hardware
Thanks in advance

[peterhinch]

Recognising a sound is trickier than you might think. Are there any other indications that it has finished work? An LED going off or some part physically moving? These would be easier to detect.

[PatLub85]

Hi Peters,
no I don't have these indicators.
I thought I could make a signature of the ringtone that would be easier to compare.
However is it possible to do it with so little memory of an ESP32?

[peterhinch]

Comparing sounds is computationally difficult. There can be differences caused by room acoustics and background noise, phase and frequency differences and suchlike. One option might be to compare in the frequency domain using DFT, using correlation to compare the spectra. If you can change the ringtone there may be scope for choosing a tone with an easily recognised spectrum.

It's an interesting topic for experimentation but as far as I know there is no ready-made solution.