ultrahelimeetodil põhinev mittepurustav katse; eristatakse kahte peamist katsetusmeetodit: ultraheliläbivalgustuskatse ja ultraheliimpulss-kajakatse, ultrasonic test in which an ultrasonic source is pressed against the part to be tested, using some form of gel to act as a some coupling to the surface, and sound is passed into material and reflections on the back face are received; the two major tests are the ultrasonic transmission test and the pulse-echo test