OBJECTIVE: The aim of the present study was to compare the TM-ECochG results obtained when the electrode was placed on the superior region versus the inferior region of TM.
MATERIALS AND METHODS: Forty healthy adults (aged 29 to 50 years) participated in this comparative study. The TM-ECochG testing was conducted with the electrode placed on the superior and inferior regions of TM.
RESULTS: SP and AP amplitudes were statistically higher for the inferior region of TM (p < .05). In contrast, SP/AP ratios were comparable between the two regions of TM (p = .417).
CONCLUSIONS AND SIGNIFICANCE: In TM-ECochG recording, when the electrode was placed on the inferior region of TM, SP and AP amplitudes were greater than when the electrode was placed on the superior region of TM. On the other hand, SP/AP amplitude ratio was not affected by the location of electrode on TM. The findings from the present study could be useful to guide clinicians in optimizing TM-ECochG recording when testing their respective patients.
Method: Quasi-experimental and repeated-measures study designs were used in this study. Twenty-six adults with normal hearing (17 females, 9 males) participated. ABRs were acquired from the study participants at 3 intensity levels (80, 60, and 40 dB nHL), 3 frequencies (500, 1000, and 2000 Hz), 2 electrode montages (ipsilateral and vertical), and 2 stimuli (NB LS CE-Chirp and tone-burst) using 2 stopping criteria (fixed averages at 4,000 sweeps and F test at multiple points = 3.1).
Results: Wave V amplitudes were only 19%-26% larger for the vertical recordings than the ipsilateral recordings in both the ABRs obtained from the NB LS CE-Chirp and tone-burst stimuli. The mean differences in the F test at multiple points values and the residual noise levels between the ABRs obtained from the vertical and ipsilateral montages were statistically not significant. In addition, the ABR elicited from the NB LS CE-Chirp was significantly larger (up to 69%) than those from the tone-burst, except at the lower intensity level.
Conclusion: Both the ipsilateral and vertical montages can be used to record ABR to the NB LS CE-Chirp because of the small enhancement in the wave V amplitude provided by the vertical montage.