Skip to 5:12 if you wanna hear sound from LEDs.
It's pretty fascinating. Not much of a threat though because of smartphones.
I was thinking about putting this in technology, but I thought it would be easy enough for the non-tech-savvy to understand.
EDIT: I may be misunderstood, the description should read "An LED light can be used to transmit audio", many people are misinterpreting this to mean that the led can actually "pick up" audio like a microphone, this is not the case.