Wideband acoustic transfer functions predict middle-ear effusion

Abstract

Objectives/hypothesis: Compare the accuracy of wideband acoustic transfer functions (WATFs) measured in the ear canal at ambient pressure to methods currently recommended by clinical guidelines for predicting middle-ear effusion (MEE).

Study design: Cross-sectional validating diagnostic study among young children with and without MEE to investigate the ability of WATFs to predict MEE.

Methods: WATF measures were obtained in an MEE group of 44 children (53 ears; median age, 1.3 years) scheduled for middle-ear ventilation tube placement and a normal age-matched control group of 44 children (59 ears; median age, 1.2 years) with normal pneumatic otoscopic findings and no history of ear disease or middle-ear surgery. An otolaryngologist judged whether MEE was present or absent and rated tympanic-membrane (TM) mobility via pneumatic otoscopy. A likelihood-ratio classifier reduced WATF data (absorbance, admittance magnitude and phase) from 0.25 to 8 kHz to a single predictor of MEE status. Absorbance was compared to pneumatic otoscopy classifications of TM mobility.

Results: Absorbance was reduced in ears with MEE compared to ears from the control group. Absorbance and admittance magnitude were the best single WATF predictors of MEE, but a predictor combining absorbance, admittance magnitude, and phase was the most accurate. Absorbance varied systematically with TM mobility based on data from pneumatic otoscopy.

Conclusions: Results showed that absorbance is sensitive to middle-ear stiffness and MEE, and WATF predictions of MEE in young children are as accurate as those reported for methods recommended by the clinical guidelines.