[Characteristic analysis of otoacoustic emission compensating middle ear pressure in patients with middle ear negative pressure]

Objective:To compare the changes in distortion product otoacoustic emission （DPOAE） test results in clinical patients with negative middle ear pressure after equalizing the pressure in the external canal and the middle ear cavity. This study aims to analyze the effect of negative middle ear pressure on otoacoustic emissions and investigate the correlation between the degree of negative middle ear pressure and the changes in amplitude and signal-to-noise ratio of DPOAE. Methods:Twenty-seven clinical patients were included, with 34 ears exhibiting negative middle ear pressure. Acoustic conductance tests, pure tone hearing threshold tests, and DPOAE tests were conducted under ambient pressure and peak pressure after equalizing the middle ear pressure for all tested ears. The amplitude and signal-to-noise ratio of DPOAE before and after compensating for middle ear pressure were recorded and statistically analyzed. Results:At 1.0 k Hz, 1.5 k Hz, and 8.0 k Hz, the DPOAE amplitude under ambient pressure was significantly higher than that under negative pressure （P<0.05）. A significant difference in the DPOAE signal-to-noise ratio was observed at 1.0 k Hz and 8.0 k Hz （P<0.05）. The difference in both amplitude and signal-to-noise ratio between these two test conditions was more pronounced at 1.0 k Hz （P<0.01）. There was no correlation between the negative pressure value from the tympanogram and the change in amplitude, with a weak negative correlation trend observed only at 0.75 k Hz （r=-0.328, P=0.054）. However, a significant negative correlation was found between the negative pressure value from the tympanogram and the change in signal-to-noise ratio at 0.75 k Hz （r=-0.366, P<0.05）. Conclusion:Compensating for middle ear pressure significantly improves the amplitude and signal-to-noise ratio of DPOAE in cases of negative middle ear pressure, particularly in the medium-frequency range. The smaller the degree of negative pressure in the middle ear, the weaker the effect of equalizing middle ear pressure is, especially in the low-frequency range.