GSM electromagnetic interference is similar. GSM phones would transmit TDMA frames at a frequency of 217 Hz which couples with audio circuitry to cause speaker

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 https://www.ti.com/lit/an/snaa033d/snaa033d.pdf