Also there's the 'Audio Hotspot Attack' - https://ieeexplore.ieee.org/document/8906174 https://ieeexplore.ieee.org/document/8906174 Which uses a parametric spe

Also there's the 'Audio Hotspot Attack' - https://ieeexplore.ieee.org/document/8906174 https://ieeexplore.ieee.org/document/8906174 Which uses a parametric speaker, which uses a number of ultrasonic transducers which "emit amplitude-modulated ultrasounds that will be self-demodulated in the air"