Estimation of the air-bone gap using interleaved air-conduction and bone-conduction ABR
Degree GrantorUniversity of Canterbury
Degree NameMaster of Audiology
There is a need for monitoring of both the standard and extended frequency range during middle ear surgery. This project set out to provide a system that could receive an estimation of the air-bone gap using interleaved air conduction (AC) and bone conduction (BC) auditory brain-stem response (ABR).
This was accomplished in three different stages. First, two bone conduction transducers were calibrated using the real ear method, Békésy audiometry. Second, three different amplifiers were compared to see which would give the clearest waveforms and be most suitable for the operating theatre. The final stage consisted of testing the system with a normal hearing individual with their ears first unoccluded and then occluded to simulate a conductive loss. A 100 μs click was presented followed by both 4 kHz and 12 kHz tone bursts.
Calibration was done with a focus on the conditions that would be used in surgery, namely the TEAC and B71 occluded and unoccluded with forehead placement. Five participants took part in that part of the study, but the majority of the information came from the student and their primary supervisor.
It was found that a custom fibre optic amplifier (Patuzzi, 2018) would be most suitable for the operating theatre because it is small, battery powered and provides adequate wave forms.
Wave V of the ABR was produced with all three stimuli and the interleaving of the AC and BC. The method created has the potential to provide rapid monitoring of both frequency ranges during middle ear surgery.