Wideband absorbance tympanometry using pressure sweeps: System development and results on adults with normal hearing

Abstract

A system with potential for middle-ear screening and diagnostic testing was developed for the measurement of wideband energy absorbance (EA) in the ear canal as a function of air pressure, and tested on adults with normal hearing. Using a click stimulus, the EA was measured at 60 frequencies between 0.226 and 8kHz. Ambient-pressure results were similar to past studies. To perform tympanometry, air pressure in the ear canal was controlled automatically to sweep between −300 and 200daPa (ascending/descending directions) using sweep speeds of approximately 75, 100, 200, and 400daPa∕s. Thus, the measurement time for wideband tympanometry ranged from 1.5to7s and was suitable for clinical applications. A bandpass tympanogram, calculated for each ear by frequency averaging EA from 0.38to2kHz, had a single-peak shape; however, its tympanometric peak pressure (TPP) shifted as a function of sweep speed and direction. EA estimated at the TPP was similar across different sweep speeds, but was higher below 2kHz than EA measured at ambient pressure. Future studies of EA on normal ears of a different age group or on impaired ears may be compared with the adult normal baseline obtained in this study.