What’s interesting is that this patent suggests that Apple could actually use the phone’s accelerometer to detect an imposter’s voice through a voice activity detector. When the person speaks the key phrase, like “Hey Siri”, it passes through an algorithm based on speech rate and also the accelerometer’s signal detector to determine if it is the voice of the device’s owner.
If it is, it will proceed as per usual, if not, it won’t act on the command, simple as that. That being said, the patent seems to be more focused towards the AirPods, but Apple does note in the patent that this system could also be applied to other devices like the iPhone, iPad, HomePod mini, and more.
We should point out that for the most part, Siri is limited in what it can do while your phone is locked, so there’s not much an imposter can do as long as your phone is locked. However, having additional security measures isn’t a bad idea, but whether or not Apple actually implements this remains to be seen.