A fire extinguisher that puts out flames with sound waves

This article is blogspam and references the original source which was submitted 2 days ago: https://news.ycombinator.com/item?id=9256803

I'm having doubts that this will work well against fire burning on a non-flat surface. Flaming liquid in a wok seems to be an edge case and these guys might've designed a solution that works, but just for this particular case.

Biggest problem: the fuel stays hot and will re-ignite afterwards (you can even see it in the video).

That sufficiently intense sound waves can have fire extinguishing properties is unsurprising enough, but what I'm curious about is, how does it not blow out the eardrums of everyone in the neighborhood?

Can we use this to extinguish cigarettes too? :)