Data can be transferred using ultrasonic frequencies,
Legit Uses -
Google Tone Google Tez
Bad Thing -
It has been used in the past for malicious activity by governments (if you know, you know).
I can be used to track people, like people’s devices screaming their ID and devices receiving other devices IDs.
Imagine a mall with ultrasonic beacons, and for iOS and Google Play Services, hear that.
Reports -
https://thehackernews.com/2017/05/ultrasonic-tracking-signals-apps.html
https://www.youtube.com/watch?v=1n_8zDIFmQU
Solution ?
How to stop my devices like browsers, Windows PC, macOS, Android, and Android apps, from sending and receiving these frequencies
THis is a dead Chrome extension - https://github.com/ubeacsec/Silverdog
if you can’t trust your phone with not emitting beacon sounds all the time, that’s a problem. not with you, but with the phone.
I don’t know if google mobile services does it, butbother apps, including pre-installed ones could also do that. your best bet may be a relatively popular custom android rom, without google services but microg is fine), or banishing the “consumer” and mainstream social apps to the work profile on your phone, which you set up to automatically kill its apps when not in use.
these could be interesting too:
https://f-droid.org/packages/cityfreqs.com.pilfershushjammer
https://codeberg.org/kaputnikGo/PilferShush_Scanner