Don't think permissions don't really protect you from this. AFAIK you don't need permission to _play_ sounds at least for foreground apps. So that means in a p

Don't think permissions don't really protect you from this. AFAIK you don't need permission to _play_ sounds at least for foreground apps. So that means in a public space, it doesn't matter if your mic is disabled - if anyone _else_ gave permission for an app to use the mic, their phone hear your phone transmitting ultrasound, allowing you to be tracked.