Technology

Behold:

https://www.researchgate.net/figure/Electrical-conductivity-of-banana-at-different-ripening-stages-with-the-help-of_fig5_317486785

5.4 Electrical Conductivity Measurement This method includes electrical impedance spectroscopy (EIS) and dielectric analysis (DEA). The physical state of a material is measured as a function of frequency in EIS and the frequency ranges from 100 Hz - 10 MHz. It is simple and easier technique used to estimate the physiological status of various biological tissues49-52. Experimental frequency response of impedance is characterised by electrical equivalent circuits of materials. The physical properties of materials can be quantified by monitoring the changes in parameters at the equivalent circuit, among various equivalent models proposed53-54. DEA measurement is used in high frequency areas, generally 100 MHz - 10 GHz. DEA is used in moisture estimation and bulk density determination

So a overripe banana is an interesting high-pass filter, kinda like a capacitor, though the big takeaway is the conductance vs ripeness.

So if you want to test if a banana is ready to eat, hook it up… preferably with several other bananas in series. If the music is too loud, they are ready. Too quiet, and it’s not time yet.