This is mumbo-jumbo. They have undoubtedly discovered a way to modulate the propagation of sound waves, but that falls under the heading of known physics. "4D" is just an advertising gimmick.

"Metamaterials" can include materials that can be fabricated to have (e.g.) a negative refractive index. They do this by ordering the electromagnetic properties of the material at a dimensional scale equal to or smaller than the wavelengths of the light (or microwaves) they want to affect.