An electroacoustical analog for estimating sound pressure level at the tympanic membrane at high frequencies.

Abstract

For various applications, it is useful to know the sound pressure level (SPL) at the tympanic membrane (TM). However, measuring the SPL close to the TM is not clinically feasible, due to safety and discomfort concerns. Therefore, it is desirable to estimate the SPL at the TM using measurements away from the TM. This is challenging at high frequencies where the effect of canal geometry becomes significant as the wavelength of the acoustical source becomes comparable to the dimensions of the canal. In this study, an electroacoustical analog was used to estimate the SPL at the TM for ten participants. The analog is comprised of a transducer (i.e., sound source), occluded ear canal, and the middle ear [Pascal et al. (1998)]. The ear model was optimized for each individual using a 2‐parameter fit using real ear measurements further away in the canal. The optimization did not require inputs that may be difficult to obtain such as the exact canal geometry. A simulated transfer function was created and applied to each measured real‐ear response to generate the estimated response at the TM. The model was verified using the SPL measured at the TM.