Wideband acoustic transfer functions predict middle-ear effusion.

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.