ultrahelidefektoskoopia, mis põhineb uuritava eseme pinnalt materjali sisse suunatud ultraheliimpulsside peegeldumisel (vastukajamisel), ultrasonic defectoscopy (ultrasonic inspection) in which a short pulses are introduced into a testpiece at regular intervals of time while some or all of the energy is reflected; the proportion of reflected energy id dependent on the size of reflecting surfaces (flaws)