Recent advances in artificial intelligence (AI) and machine learning have enabled new game-changing technologies for humans to interact with machines using voices. It is now possible for everyday users to converse with voice assistants, such as Bixby, Siri, Google Assistant to set the alarm, call a friend, arrange appointments on the calendar, etc.
Besides improving the living standards, these new technologies also change the landscape of cyber threats.
Recently, scientists have demonstrated that these voice assistant systems are susceptible to signal injection at the inaudible frequencies. Until now, most of the existing works focus primarily on delivering a single command via line-of-sight ultrasound speaker or extending the range of this attack via speaker array. However, besides air, sound waves also propagate through other materials where vibration is possible.