[puglr]

"reconstruct conversation glass vibration" brings up a lot of relevant results from a 2014 story from MIT. Sounds like it works in principle with any medium that can have its visible vibrations monitored (bag of chips is the main example, but they talk about other options such as plants or a glass of water).

[bambax]

Yes I think that's what I was referring to; I may have confused glass and chips but it seems it works with either medium.

https://news.mit.edu/2014/algorithm-recovers-speech-from-vib...