In Ultrasonic Testing (UT), very short Ultrasonic pulse-waves with centre frequencies ranging from 0.1-15 MHz and occasionally upto 50 MHz are launched into materials to detect internal flaws or to characterize materials. The technique is also commonly used to determine the thickness of the test object, for example, to monitor pipework corrosion.

Ultrasonic Testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albiet with less resolution. It is a form of non-destructive testing used in many industries including aerospace, automotive and other transportation sectors.