ultrasonic

1. (acoustics) Beyond (higher in frequency than) the range of sound perceptible to the human ear; with a frequency of 20 kilohertz or higher.Examples: "The wheel shop also has equipment for ultrasonic testing of axles for flaws; and systematic checking of locomotive axles and crank pins is carried out as they pass through the shops."; "When an ultrasonic beam is fired at the microcannons, the emulsion evaporates, expanding rapidly into gas. This creates enough force to push the nanobullets out at velocities reaching several metres per second."