Effects of middle ear pressure compensation on evoked otoacoustic emissions and power absorbance in adults

This study investigated the impact of positive and negative middle ear pressure (MEP) on evoked otoacoustic emissions (EOAEs) both distortion-product OAEs (1.5 to 8 kHz) and transient evoked OAEs (1 to 5 kHz), as well as wideband acoustic immittance measures of power absorbance (PA) in a normal-hearing young adult population between the ages of 18 and 35. The effectiveness was evaluated, of testing at ambient compared to a compensated pressure level corresponding to participants’ tympanic peak pressure. Outcome measures were analyzed considering factors of gender, ethnicity, frequency, and MEP magnitude. For each participant, testing was conducted at a natural state MEP and at a MEP level induced by either the Toynbee or Valsalva maneuver. Titan Suite by Interacoustics was used to collect all measures and is the only commercially available system for assessing EOAEs at a compensated pressure level. One-hundred and four participants (67 female and 37 male, providing 208 ears) were recruited for testing. EOAE absolute amplitude and PA varied significantly as a function of test frequency and across test pressure conditions. Significant differences in PA and EOAE measures were observed between gender and ethnic groups. Mean PA magnitude at frequencies ≤4 kHz was significantly greater testing at peak compared to the ambient pressure in the presence of MEP deviating from 0 daPa. EOAE amplitude was similar between the post-maneuver (induced MEP) condition and baseline measures when assessed at peak pressure. Frequency-dependent changes in PA magnitude with alterations in MEP and ear canal pressure were linked to frequency-dependent changes in EOAE amplitude. Results of this study suggest clinical benefit for a more accurate assessment of middle ear status and cochlear integrity for patients with abnormal MEP when EOAE are assessed at a compensated pressure level. This study provided a database of PA measures over a range of MEPs measured at both ambient and tympanic peak pressure.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat