What is really the Mel-filterbank?
This was my first google hit: https://medium.com/analytics-vidhya/understanding-the-mel-spectrogram-fca2afa2ce53
It seems to explain both how and why?
Mel frequency binning is afaik only used when human perception is involved. Either directly, or for signals that have probably been adapted to human hearing (such as human speech). It is a way to represent signal information in a way that mimics «low level auditory perception», or could be seen as removing perceptually redundant information.
I have not understood why it is that we generally have the same temporal reolution in narrow low frequency bands, as in wide high frequency bands. Historically, it may have been due to limited processing power and the efficiency of a single STFT windowing process. And/or it could reflect the limited neuron firing rate after the acoustic-mechanical filtering carried out by our ear.
But from a dsp perspective, I would expect a variable time/frequency resolution, where high &amp; wide bands gets more temporal resolution.