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Wideband energy absorbance for middle ear diagnostics
18 April 2018 (online)
The measuring system for middle ear diagnostics presented in this work gathers the absorption capacity of sound energy (energy absorbance, EA) in a wide frequency range and provides more data on the middle ear in contrast to the clinical tympanometry. This study aims to demonstrate characteristics of wideband EA in normal-hearing adults, and the test-retest reliability is analyzed.
Wideband EA was obtained in 18 ears of normal-hearing adults using a click stimulus (0.226 to 8 kHz), varying the air pressure in the ear canal. Pressure and frequency dependent EA was reduced to two-dimensional representations and key data in order to present the data in a clinically acceptable manner.
Bandpass absorbance tympanograms show a single-peak shape for the pressure dependence of the absorbance averaged over frequencies from 0.38 to 2 kHz and respectively a M-shape for frequencies from 3 to 4.6 kHz. Frequency depending energy absorbance rises with increasing frequency up to about 1 kHz, shows a plateau between 1 and 3 kHz, and falls steeply for frequencies above 3.5 kHz. In the present implementation clinically acceptable test-retest reliability of the measured energy absorbance was obtained for frequencies up to 5 kHz.
Unlike clinical tympanometry, the registration of wideband EA has the potential for improved middle ear diagnostics. EA may be reduced to various key data for differentiating multiple middle ear disorders and normal findings in a clinically practicable manner. However, further research on diseased ears is needed to demonstrate the actual usefulness of these parameters for differential diagnosis.