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.
(too late to edit)
I remembered this example of "unintentional amplitude modulation" of a strong AM RF signal: touching vegetation against a (presumably AM) radio mast. "Listening radio with grass"
The second is "sensory processing disorder", which is a characteristic or symptom of autism; I can't find it in the main article, but it's probably because some people with sensory processing disorder are more sensitive to coil whine / "hearing electricity", or more likely to consciously experience what most people consider background noise.
I'm really sensitive to this (I used to be even more, but, I'm guessing, after years of going to disco's and rock concerts, my earning lost some of its sharpness - on a side note, I used to be able to recognize basically anyone's voice - even distant acquaintances - and lost some of that with time, probably because of this reduction in hearing.).
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.
GSM electromagnetic interference is similar.
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
(too late to edit) I remembered this example of "unintentional amplitude modulation" of a strong AM RF signal: touching vegetation against a (presumably AM) radio mast. "Listening radio with grass"
https://youtu.be/b9UO9tn4MpI
https://news.ycombinator.com/item?id=41462574
The Yamaha TX81Z was famous for this coming off the transformer. There was a revision that added a shield and a service upgrade part forty years ago.
A few years ago, I fixed one with part of a bean can.
What's the term for when you put a phone near a speaker and when it's about to get a text or a call, the speaker goes "didididit-didididit"?
See my comment about GSM
In my village we call those Tesla Coils...
https://youtu.be/fLiji1YgDGU
Why is the first page listed under „See also“ the article for Autism?
The second is "sensory processing disorder", which is a characteristic or symptom of autism; I can't find it in the main article, but it's probably because some people with sensory processing disorder are more sensitive to coil whine / "hearing electricity", or more likely to consciously experience what most people consider background noise.
Like a speaker?
I had a GPU which whined when you would scroll a window (like a long web page).
I'm really sensitive to this (I used to be even more, but, I'm guessing, after years of going to disco's and rock concerts, my earning lost some of its sharpness - on a side note, I used to be able to recognize basically anyone's voice - even distant acquaintances - and lost some of that with time, probably because of this reduction in hearing.).
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.