Summary of: Marshall, L., Heller, L. M., & Westhusin, L. J. (1997). Effect of negative middle-ear pressure on transient-evoked otoacoustic emissions. Ear and hearing, 18(3), 218–226. https://doi.org/10.1097/00003446-199706000-00005
Otoacoustic emissions (OAEs) are good indicators of inner-ear changes over time. OAEs measured in response to a transient signal are referred to as transient-evoked OAEs (TEOAEs). Because the inner ear, or cochlea, is positioned beyond the middle-ear, changes in middle-ear pressure may influence the measured level of OAEs. The purpose of the present study is threefold: 1) to demonstrate the effect of negative middle-ear pressure on the TEOAE stimulus and response, 2) to demonstrate the effect on the TEOAE subsequent to compensating for negative middle-ear pressure, and 3) to examine the effect on TEOAEs by applying positive ear-canal pressure to simulate negative middle-ear pressure. This study presents a case study over the course of 6 months from a single participant with frequent negative middle-ear pressure. Small amounts of negative middle-ear pressure affect both the stimulus amplitude and the TEOAE response. TEOAE amplitude progressively decreases for frequencies below 3150 Hz as the magnitude of negative middle-ear pressure increases. TEOAE amplitude changes little with changes in middle-ear pressure for frequencies above 3150 Hz. Compensating for negative middle-pressure restores the spectra of the stimulus and TEOAE relative to when middle-ear pressure is near ambient pressure for frequencies above approximately 2 kHz, but increases TEOAE amplitude for frequencies below approximately 2 kHz. Simulating negative middle-ear pressure by applying positive ear-canal pressure approximates similar effects on the TEOAE amplitude as do’s negative middle-ear pressure. These results suggest that compensating for negative middle-ear pressure bypasses the effects of negative middle-ear pressure on the TEOAE.