As seen on TV, this is the development of the Directional Security device called the LRAD, it's used in maritime security to overwhelm aggressors, and it can cause the sensation of hearing things from nowhere but the ultrasonic vibrations do cause your ears to hear the sound unlike Radio Hearing Effect we follow later.
This method enables a speech waveform to be fit into a smaller representation. It allows people to send speech using less information, and for the signal to still be intelligable. It mentions transmission though physical mediums such as earth and water.
Method of causing a subject to hear a sound using bone conducted ultrasonic sounds, that resonate to cause the actual sound in the ear. It's a silent speaker device.
I think this is related to the discovery that ultrasound can cause resonating vibrations in the ears by vibrating the target with inaudible ultrasound. Sound appears to be coming from inside you.
Method of using ultrasonic waves as an undetectable communications device, using something like a building as a carrier medium.
Description of the directional uses of LRAD technology in static, mobile and man-portable for things like crowd control and as security for buildings.
Looks like a handheld LRAD style device causing people nearby to hear without feeling where the sound waves are coming from, but the ear does vibrate.