Directional sound

Directional audio is an emerging technology with enormous potential in a wide range of commercial settings.
The level of audio “directivity” varies widely in today’s speakers. When we talk about directivity, we are referring to the property of how a speaker sends sound in different directions. When sound is “directional,” it travels along a particular axis with minimal diffusion.
At present, there are several methods for generating directional sound as follows:
Loudspeaker array: On the horizontal plane, spatially control the audible sound beam. This method of producing concentrated sound is expensive and cannot be produced by small speakers. Directivity is low.
Sound Dome: Focus sound waves to the listener under the dome. Directivity is limited, depending on the size of the dome, and can only be deployed for overhead applications.
Parametric (or ultrasonic) loudspeaker: modulates an audible sound signal onto an ultrasonic carrier and projects the signal through an ultrasonic transmitter, producing audible sound in a compact columnar structure. This type of speaker provides maximum audio directionality and can be developed in different transmitter sizes and shapes.