The effect of static middle ear pressures on the hearing threshold

Area of Science:

• Otolaryngology
• Audiology
• Physiology

Background:

• Middle ear pressure is a critical factor influencing accurate hearing assessments.
• Understanding the effects of static tympanic pressure gradients is essential for diagnostic audiology.

Purpose of the Study:

• To investigate the impact of induced middle ear underpressure on hearing sensitivity across various frequencies.
• To determine the relationship between the magnitude of middle ear pressure difference and the degree of hearing threshold shifts.

Main Methods:

• Six normal human ears were subjected to controlled middle ear underpressure (5, 10, 15 cmH2O).
• Hearing threshold shifts were measured using a self-recording Békésy audiometer during pressure equilibration.
• Thresholds were assessed across multiple test frequencies.

Main Results:

• Hearing threshold loss was most pronounced at 0.5 and 1 kHz, with less loss at 4 kHz.
• A threshold gain was observed at 2 and 6 kHz.
• Increased middle ear underpressure led to greater threshold shifts across all tested frequencies.

Conclusions:

• Static tympanic pressure gradients demonstrably affect hearing sensitivity, necessitating middle ear pressure control during audiometric testing.
• While significant, minor middle ear pressure variations may be negligible when evaluating summed hearing thresholds between 2 and 8 kHz.