I also like looking at spectrograms of birdsong. I had a setup where I would see the spectrogram of sound coming through my microphone in realtime. I would place it on the windowsill and a few times I would see very faint birdsong I hadn't noticed with my ears, and then I would "tune in" my ears to that frequency range and I would hear it.
Thinking about it the ideal form factor for a realtime spectrogram for the hard of hearing (or the curious) would be something like Google Glass. (Originally thought of a smartwatch but that doesn't make much sense for an additional sense).
There's a project that's the opposite of this where a colorblind man attached a sensor to his head that converts color into sine waves he can hear. Adam Montandon. Eventually this electronic sense became a natural part of his experience and he began to dream in "color".
Funny think about birds! Yesterday, as I was preparing to release the app, birds were singing outside of my window (coronavirus lockdown, so quiet), and I noticed how fun to look at their songs on my app! I've spent literally 30 minutes looking at that :) I've posted a link to birdwatchers reddit :)
Normally this would affect his ability to hear certain frequencies, but he’s so accustomed to working with raw waveforms, he’s not too concerned. He knows exactly what the sound he wants should look like.