This technique looks interesting, but from what I gather it only works with incandescent light bulbs.
https://arstechnica.com/information...p-by-watching-a-light-bulbs-variations/?amp=1
https://arstechnica.com/information...p-by-watching-a-light-bulbs-variations/?amp=1
The researchers found that the tiny vibrations of the light bulb in response to sound—movements that they measured at as little as a few hundred microns—registered as measurable changes in the light their sensor picked up through each telescope.

