PP1118 - Impact of Pressure Equalization Tubes on Audiometric Thresholds in Children

Abstract: Obtaining accurate audiometric thresholds in children can be challenging, as rapidly changing ear canal characteristics (e.g., volume) and self-generated noise can introduce variability into measurements. This is a greater challenge when assessing children with pressure equalizing (PE) tubes, due to middle ear involvement. PE tubes are a common intervention for otitis media, but with the change in ear-canal volume, this intervention can affect audiometric thresholds, specifically based upon the transducer used. FASTRAK audiometry is a novel approach to audiological evaluation, which aims to provide a better understanding of how differences in ear-canal acoustics affect audiometric thresholds using ear-canal level calibration.

Summary: Rationale:
Conductive hearing loss is the most prevalent form of hearing loss in children, with otitis media being the primary cause (Kennedy et al., 2024). Monitoring hearing in children with otitis media with effusion is critical to track threshold changes before and after intervention . The insertion of pressure equalization (PE) tubes can mitigate hearing loss from effusion but complicate audiological evaluation by substantially altering ear-canal volume (Browning et al., 2010; Martin et al., 1997; Voss et al., 2000). Current audiometric evaluations do not account for individual differences in ear-canal acoustics (Voss et al., 2000; Voss & Herrmann, 2005). Additionally, there is not a way to account for threshold elevations from self-generated noise, which includes noises such as throat clearing, coughing, breathing, and moving during assessment (Buss et al., 2016).
Sound pressure level (SPL) in the ear canal is not measured during standard audiometric assessments, as calibration assumes equivalence between transducer and ear. This assumption is inaccurate for children, especially those with PE tubes. Depending on canal size, transducer, and middle ear pathology, sound pressure measurements can vary up to 35 dB (Voss et al., 2000). Additionally, children are less likely than adults to suppress self-generated noise during testing (Buss et al., 2016). Given ear-canal volume changes from PE tubes, we aim to determine whether audiometric procedures that account for canal volume and self-generated noise yield different thresholds.
This project is part of the Finding Appropriate Solutions to Treat Reduced Audibility in Kids (FASTRAK) study, a multi-site collaboration validating clinical tools to support identification of children with hearing loss. Using FASTRAK audiometry, which accounts for ear canal acoustics and monitors self-generated noise, we are extending research to children with PE tubes.

Design:
Data were collected from 40 ears of children ages 2–12 with at least one functioning PE tube. The audiometric protocol included otoscopy, wideband tympanometry, real-ear-to-coupler difference (RECD), an experimental audiogram, and a clinical audiogram. The experimental audiogram was administered via computer-based software that monitored ear-canal noise levels and acoustics. Audiometric thresholds were measured at 0.25, 0.5, 1, 2, and 4 kHz.

Results:
Data collection is ongoing but will be completed before the conference. Preliminary results from seven children indicate thresholds at 250 and 500 Hz are routinely outside the normal range in ears with PE tubes. With FASTRAK audiometry, all thresholds in ears with PE tubes appear elevated, likely due to higher impedance from increased ear canal volume.

Conclusions:
Audiometric procedures that account for ear canal acoustics and self-generated noise provide more accurate characterization of hearing sensitivity than clinical audiometry referenced to a 2cc coupler. Given the known effects of PE tubes on thresholds, particularly below 1.5 kHz, and the influence of transducer type, it is important to use clinical tools that account for these differences. The goal of FASTRAK audiometry is to provide an alternative clinical tool to yield representative thresholds when testing populations that deviate from average values.