If it brings you any more motivational drive, (as someone who has no background in signal processing) it absolutely blows my mind that technology like Shazam works, and I've always wanted to figure it out.

One of my backburner tasks that will probably remain forever is to get a grip on DSP, obtain General/Amateur ham radio license, mess around with it, yadda yadda yadda.

I've always meant to get around to digesting this article:

https://news.ycombinator.com/item?id=9870408 ("How Shazam works")