Electromagnetically Induced Acoustic Noise
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The Wikipedia article on Electromagnetically Induced Acoustic Noise sparks a discussion on the phenomenon and its relation to everyday experiences, such as coil whine in electronics.
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GSM phones would transmit TDMA frames at a frequency of 217 Hz which couples with audio circuitry to cause speakers to emit a characteristic buzzing sound.
Even though it's a radio frequency signal which is outside the range of human hearing (like 800-900 MHz or higher), the signal interacts with any non-linearity in the audio circuitry (think of the diode in a crystal radio), which basically performs unintended amplitude modulation of the pulsed RF electrical signal into something like a 217 Hz square wave, which is in the audible range.
This has gone away as phones stopped using GSM. Newer standards emit more of a continuous waveform which doesn't cause these audible frequencies to be generated.
https://www.ti.com/lit/an/snaa033d/snaa033d.pdf
https://youtu.be/b9UO9tn4MpI
https://news.ycombinator.com/item?id=41462574
A few years ago, I fixed one with part of a bean can.
https://youtu.be/fLiji1YgDGU
It's really ,really distracting and enervating. Specially, because most people around you can't ear it and think you are just being picky. Imagine a TV, and that noise is there all the time and you can't watch anything in peace because you keep earning that high pitched noise in the background.