Evaluating measurement accuracy of ear-canal reflectance using a conical horn

Acoustic reflectance is fundamental to the set of ear-canal measures collectively known as wideband acoustic immittance (WAI). The potential of WAI to inform diagnostic audiology, and its broader clinical adoption, remain active areas of study. Individual variability, challenges in diagnostic interpretation, and the lack of adopted standards for quantifying measurement accuracy are barriers to wider clinical use. This study builds upon a previously proposed theoretical framework for validating reflectance measurements. Specifically, we demonstrate a method for checking (1) the accuracy of WAI device measurements and (2) consistency across repeated measurements. We describe an updated acoustic horn design and use it as a physical reference waveguide with a known analytic solution to verify measurement accuracy. Quantitative comparisons of reflectance measurements to the horn's analytic solution were performed using a total of six three-dimensional (3D)-printed horns. These comparisons yielded Pearson correlations of 0.98-0.99 and maximum absolute deviations in reflectance magnitudes below 0.02. The proposed horn is inexpensive to reproduce and could function as part of a reference standard for validating acoustic reflectance, help explain sources of variability, and contribute to wider clinical acceptance of WAI by increasing user confidence in measurement consistency and accuracy.