Hector Martin on Nostr: Like an ultrasound cleaner? I can hear those things too. Either they're not actually ...

Like an ultrasound cleaner? I can hear those things too. Either they're not actually ultrasound or they're so high power that the subharmonics produced by physical processes are clearly audible.

Same with audio: Nobody can hear ultrasound... but we can damn well hear the intermodulation products you get when you feed two or more ultrasound frequencies into any real world, imperfect system with more than 0% distortion!