There is provided detection instrumentation for the detection of transverse rail defects in rail head hitherto considered untestable on account of acoustic signal attenuation problems of horizontal lamination defects. The detection instrumentation comprises a pulse-echo acoustic transducer having a wear face for contacting a fillet of the rail and being aimed towards a head of the rail such that the transmitter transmits acoustic signals into the head and the receiver receives acoustic signals reflected at differing depths within the head. A signal receiver operably coupled to the receiver times the acoustic signals according to a timeseries railhead depth position scale. Analysis of the depth positions of the reflected acoustic signals according to relative positioning of the instrumentation along the rail may identify the transverse rail defects.