Or coating entire walls and ceilings to track people with ultrasound without them even knowing. Depending on how good the resolution is, maybe even identifying

Or coating entire walls and ceilings to track people with ultrasound without them even knowing. Depending on how good the resolution is, maybe even identifying people? > Because the tiny domes are vibrating, rather than the entire film, the loudspeaker has a high enough resonance frequency that it can be used effectively for ultrasound applications, like imaging, Han explains. Ultrasound imaging uses very high frequency sound waves to produce images, and higher frequencies yield better image resolution. > The device could also use ultrasound to detect where a human is standing in a room, just like bats do using echolocation, and then shape the sound waves to follow the person as they move, Bulović says.