COMPARISON OF AIR-CONDUCTED AND BONE-CONDUCTED BRAIN-STEM AUDITORY-EVOKED RESPONSES IN YOUNG-DOGS AND DOGS WITH BILATERAL EAR CANAL OBSTRUCTION

Brain stem responses to air- and bone-conducted stimuli were analyzed in 11 young dogs, using an in-the ear transducer and a vibrator design ed for human hearing tests, respectively. The mean thresholds were 0 t o 10 dB for air-conducted stimuli and 50 to 60 dB for bone-conducted s timuli. The wave forms and inter-peak latencies of the waves of the au ditory evoked responses elicited by air-conducted and bone-conducted s timuli were similar. The indicated that the signals had the same origi n and thus both the air-conducted and the bone-conducted responses cou ld be considered to be auditory responses. Measurement of air-conducte d and bone-conducted brain stem- evoked responses in five dogs with bi lateral chronic obstructive ear disease revealed thresholds of 50 to 6 0 dB for air-conducted stimuli and 60 to 70 dB for bone-conducted stim uli. By comparison of these results with those in the 11 young dogs, i t could be concluded that there was hearing loss other than that cause d by obstruction of the ear canals.