Given an audio or video file, it’s possible to determine where and when it was recorded based on the electrical power grid’s hum in the background. Small fluctuations in the power supply to devices and appliances that are close enough during the recording, while not perceptible to our ears, can be picked up by electric network frequency (ENF) algorithms and matched to a database.
I’m amazed that this is possible. There are a few limitations, such as the spatial resolution (matches are typically accurate within a few dozen miles only), the length of the recording (at least a few minutes to provide enough data) and obviously the requirement that devices emitting the hum are connected to the grid and close enough for the microphone to pick up.
While I don’t know for sure, I think magician Seth Raphael’s animal trick is based on a similar principle. Probably the device that you access the website with makes an inaudible hum signifying your animal that gets picked up by a computer at the other end of the phone number you call.
Nehaveigur 