Abstract: An non-destructive testing method employs an ultrasound generator which provides a beam having an axis which intersects the outer surface of an object to be tested at an angle relative to a line normal to the surface which is in the range of 23.degree. to 28.degree.. A longitudinal mode wave and a shear mode wave are propogated within the object and the shear wave is converted into longitudinal mode waves by reflection from an opposite surface of the object. The propogated and mode converted waves are reflected from different portions of a defect and the echos arrive serially in time at a receiver transducer. The ultrasound generator and receiver transducer are sonically isolated. The received signals have a favorable signal-to-noise ratio and the times of receipt thereof are employed to determine the dimensions of a detected defect.