Generally speaking, ultrasonic refers to the sound wave with frequency larger than 20 KHz which is beyond the upper limit of human ear. Ultrasonic is characterized by strong beam property and being easy to collect energy. through focusing. Ultrasonic is also an energy form, and when the intensity exceeds a certain value, it can affect, change and damage the state,character and structure of matters through its interaction with sound bearing medium (commonly called ultrasonic power).
In real life, high pitch sound is created by high frequency, and alternatively, the low and base tone is created by low frequency.
Ultrasound is no different from ‘normal’ (audible) sound in its physical properties, except in that humans cannot hear it. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Typical ultrasonic frequencies used for cleaning purpose are from 20 kHz to 80 kHz.