“Metasurfaces are engineered materials that manipulate wave behaviour in ways that natural materials cannot,” said Zhong. “In ...

Ultrasonic beams fired ... to manipulate the properties of waves. This structure, known as a metasurface, creates ...

In a nutshell, special projectors beam self-bending ultrasonic waves that only produce audible sound (be it speech, music, tones, etc.) at a pre-determined intersection point. Outside of that ...

A technology has been developed that emits two types of ultrasonic ... wave, but if the sound waves are strong enough, they can generate a new frequency. For example, when two ultrasound beams ...

"When two ultrasonic beams of slightly different frequencies, such as 40 kHz and 39.5 kHz, overlap, they create a new sound wave at the difference between their frequencies – in this case ...

Noise can be 'cancelled' by playing a reversed sound wave back at your ears ... audible enclaves' using nonlinear self-bending ultrasonic beams (via Futurism). And if that's all gobbledygook ...