[PavlovsCat]

I had something similar-ish with a desktop PC: when I plugged headphones into my amp and that into motherboard sound output, I could hear all sorts of faint squelchy noises that seemed to correlate both with what is going on on the screen as well the CPU. Some things always sounded the exact same (like running a certain command etc.)... it was both very fascinating and annoying. If a program sometimes ran fine and sometimes crashed, I could tell by ear right when either happened, etc.

[redcalx]

Back in the days when CPU speed was measured in single digit MHZ (e.g. Amiga 68000 at 7mhz, ZX Spectrum at 6Mhz?), I had a hard time hearing anything other than CPU noise on standard FM radios. You could indeed hear algorithms running very clearly, it's something I considered to be useful during a time when I was learning about CPUs and computer programming.

[dalke]

People also harnessed that technique to playing music on a radio via RF noise, before sound cards were cheap. The thread at https://news.ycombinator.com/item?id=11203951 point to some examples.