Evoked otoacoustic emissions (EOAE) and bone conduction stimulation. A preliminary report.

Otoacoustic emissions were evoked (EOAE) in 6 normal-hearing subjects by both bone (BCS) and air conduction stimulation (ACS). Four subjects affected by unilateral otosclerosis were also examined in order to determine the role of the ossicular chain in EOAE transmission to the eardrum. In normal-hearing subjects, EOAE by BCS showed the same characteristics as those evoked by ACS. The morphological features remained unchanged over a period of 4 months and their amplitude increased non-linearly with increasing stimulus intensity. In subjects with unilateral otosclerosis before surgery, no EOAE could be elicited by ACS from the otosclerotic ear, whereas they could be recorded by BCS. After stapedectomy, EOAE could be obtained by ACS too. These results suggest that the ossicular chain is important but not essential in the transfer of the EOAE to the eardrum.