Method and apparatus useful in the inspection of a target comprises scanning the target with a pulsed acoustic beam, sensing the pulsed beam after it has been modified by interaction with the target, producing a time-domain signal indicative of the modifications, processing the time-domain signal to produce a frequency domain representation of the modifications, and producing an image-wise display of the frequency domain representation of the modifications. In one execution disclosed, the frequency domain representation is altered and then reconverted to a time domain signal before display.