Predictive value of the angle of acoustic reflectometry

Impedance tympanometry and acoustic reflectometry tracings were obtained on 406 ears of children between 4 and 16 years of age. The angle formed by the acoustic reflectometry tracing was measured. The reflectivity and the angle of the curve were compared with tympanometric results. Analysis of data on 182 normal ears and 224 abnormal ears revealed a sensitivity of 76.3% and a specificity of 89.6% when a reflectivity of 5.0 was used as the cut point. Utilizing a cut point of 90 degrees resulted in a sensitivity of 92.8% and a specificity of 93.9%. Using both a 5.0 reflectivity and a 90-degree angle as cut points improved sensitivity to 98.7% and specificity to 94.5%.