Twin ultrasound transducers create highly focused audio Curved sound waves aren't audible ... announced their Hypersound speakers which used transparent glass to create "highly directional audio".

Sound is a vibration that travels through air as a wave. These waves are created when an object moves back and forth, compressing and decompressing air molecules. The frequency of these vibrations is ...

Crucially, the sound waves — specifically, ultrasound waves — used to create the audible enclaves can't be heard along the path they travel and can even be bent to avoid obstacles. Only when ...