The effect of static tympanic pressure gradients on hearing sensitivity in normal subjects.

The effects of static tympanic air pressure gradients on hearing sensitivity was studied by introducing overpressures of 100 mm H2O to 400 mm H2O into the ear canals of 22 normal subjects. Sweep frequency threshold measures were obtained using a pressure-tight probe transducer driven by a Bekesy automatic audiometer. These gradients of tympanic pressure disequilibrium produced threshold losses through 4000 Hz, most prominently for the region of 500 to 1000 Hz, that increased systematically with the degree of overpressure. The data may be useful in estimating the degree of conductive loss associated with middle ears presenting retraction without effusion and normally compliant though negatively skewed tympanograms.