Hiding-type speech communication using ultrasonic carrier technology

A speech transmission method is presented to transmit an audible sound wave by an ultrasonic carrier frequency modulation with a characteristic of directional propagation. The modulated sound wave is propagated with the ultrasonic carrier to the appointed position, and then the original speech will be produced after getting rid of the ultrasonic carrier, thereby achieving the objective of speech transmission in a selected orientation due to ultrasonic high directionality meanwhile it can hide the communication voice data during its transmission.