Figure 1.

ABR recordings for a 3-year-old child with AN/AD type hearing loss. The dotted line represents the point at which the stimulus reached the cochlea. The top tracings show no repeatable potentials to alternating clicks presented at 100 dBnHL. The middle tracing pairs show repeatable cochlear microphonic responses but absent brain stem response waveforms to unipolar stimuli at 80 dBnHL. The asterisks indicate the positive peaks in the cochlear microphonic waveform. The final tracings, in which only the stimulus artefact is evident, were obtained to rarefacting clicks presented with the tubephone clamped.