Synonyms of the word

ultrasonic

• adj. (acoustics) Beyond (higher in frequency than) the range of sound perceptible to the human ear; with a…

inaudible

• adj. Unable to be heard or not loud enough to be heard.

supersonic

• adj. (of a speed) greater than the speed of sound (in the same medium, and at the same temperature and pressure).
• adj. (colloquial, of a sound) ultrasonic, having a frequency too high to be audible.
• n. An aircraft that can travel at the speed of sound.

unhearable

• adj. That cannot be heard.