A method includes receiving data characterizing a first acoustic signal reflected by a first defect in a target object, and a first depth of the first defect relative to a surface of the target object. The first acoustic signal is detected by a detector located at a first location on the surface of the target object. The method also includes assigning a defect color to the received data based on an amplitude value associated with the first acoustic signal and one or more of a first predetermined threshold value and a second predetermined threshold value associated with the first depth. The method further includes rendering, in a graphical user interface display space, a first visual representation of the first acoustic signal in a graph including a first axis indicative of target object defect depth and a second axis indicative of amplitudes of acoustic signals detected by the detector. The first visual representation of the first acoustic signal includes the assigned defect color.