The hidden background noise that can catch criminals

Reminds me of the 'mains hum' technique that was used to identify videos. Can also be done with light. ▶ this video link

Probably not practical but there was an interesting video by Tom Scott where investigators used the electrical hum background noise to determine when something was recorded. Maybe there is a way to audio record something to prove location. ▶ this video

I'm writing a open-source library ( link ) and a webapp ( link ) that detects the Utility Grid noise emitted by electrical devices (A/C, motors, appliances ...) from Video/Audio recording. It then tries to date the recording by matching it to historical data. The signal processing part is getting decent. I'm still trying to collect more reference signals in RU, UK, China and Japan. Tom Scott made a video about the idea: ▶ this video

According to a Tom Scott's video[1], you can use background noise emitted by electricity to prove that a recording has been taken at a certain time and place. [1]: ▶ this video

A video on the same subject: ▶ this video I really enjoy Tom Scott. Everything he puts out is wonderfully concise.

If this is interesting to you or your kids, here's a less detailed but pretty accessible video [1] explaining how mains hum forensics work, complete with British accent. [1] ▶ this video

If you haven't already seen tom Scott's video on background noise giving the location of a recording due to power line frequencies being subtly different I recommend it. ▶ this video

There are companies that already provide this kind of service so it might be interesting for you to combine efforts: ▶ this video