Eli5: how do ultrasound heaters work?


I was looking for an ultrasound therapeutic heater , and I googled but couldn’t find a blueprint or a doodle drawing that explains how those portable machines usually work

is it some kind of speaker that is set on a certain type of frequency??? (sorry if it sounded stupid but that’s where my imagination got me)

In: 2

You know that thing about somebody singing a note and glasses breaking? That is a real thing. Sound waves can cause things to vibrate, and if they line up with the rhythm it vibrates in anyway it can either make it vibrate more or less. Glass cracks when the sound waves make the glass vibrate more and the glass cannot stake the stress. Ultrasound heaters work when the air vibrates more and just gets a bit hotter.

This doesn’t answer your question, which is adequately answered by others, but to be clear to everyone there is no evidence that ultrasound therapies perform better than a placebo. They do not serve any therapeutic purpose.