Enhanced Objective Measures for Evaluating Longitudinal Changes in Within-Subject Listening Difficulty

Service Members (SMs) often report experiencing hearing difficulties that far exceed what would be expected based on standard clinical auditory evaluations. Untreated hearing concerns can impair SM's ability to function in the complex listening environments that are so common in operational settings, and in the long term can lead to increased fatigue and poorer quality of life. Hearing difficulties can be so severe that SMs are increasingly being fit with low-gain hearing aids (hearing aids that increase the volume by a small amount) despite having hearing thresholds that are considered clinically normal.

Current clinical tests are not sensitive to the sometimes subtle differences in performance and listening effort that individuals with hearing difficulties report, especially when listening to speech in background noise. Additionally, these tests can produce highly variable results: the words that people are asked to repeat vary in how difficult they are to perceive and how familiar they are with those words. Furthermore, the results of these tests can vary substantially depending on the listener's particular level of alertness or motivation on a given day.

As researchers develop interventions to improve hearing function, the limitations of current clinical tests become even more critical. To be able to say that an intervention is effective, we must (1) develop accurate and reliable measures of pre- to post-intervention changes in speech-in-noise performance; (2) reliably distinguish intervention-related benefits from general learning effects (i.e., familiarity with test words as tests are repeated); and (3) quantify the listening effort and fatigue so commonly reported, even when test performance is high. We propose a novel approach for evaluating hearing performance that will benefit future clinical trials. Our approach involves collecting a series of speech-in-noise and other auditory measurements via take-home testing performed on a tablet. We contend that this method will increase the number of data points from each patient and will better control for learning effects that can cloud our ability to detect intervention-specific benefits. We also will measure changes in pupil dilation during these tasks as a measure of listening effort and fatigue in SMs with hearing difficulties versus normal-hearing individuals.

The goal of this proposal is to develop better measures of speech-in-noise performance and listening effort that are reliably sensitive to the often subtle hearing difficulties that our SMs report. This will be especially important in future work that aims to track the benefits that are expected from a hearing restoration intervention.

Aim 1 will develop a speech-in-noise test for a portable tablet or smartphone that can collect performance and response time data across multiple at-home sessions. This strategy is expected to reliably detect smaller differences in performance than current methods by ensuring that (1) participants are fully trained on listening tasks, (2) we can collect enough data from each person to detect subtle differences in function, and (3) data are collected over enough sessions to average out day-to-day differences in alertness and motivation.

Aim 2 will evaluate using a physiological measure (pupil dilation) to measure differences in listening effort between patients with hearing difficulties and controls. We hypothesize that individuals with hearing difficulties will exhibit greater listening effort than those with fewer hearing complaints but similar hearing thresholds.

Aim 3 will investigate the use of commercially available head-mounted displays (HMDs) that can measure pupillometry as a platform for implementing the take-home hearing tests developed under Aim 1. We believe that monitoring performance and effort during listening with HMDs will allow us to track small changes in hearing function that will be at least as sensitive as laboratory-grade equipment, but much more practical for clinical applications.

Participants will be SMs with hearing difficulties that exceed what would be predicted based on their hearing thresholds or healthy control participants. Some participants will perform the listening tests while using real or simulated low-gain hearing aids. Tests will include standard or modified clinical tests of speech-in-noise and other auditory abilities. Measures of interest will be changes in performance and reaction time within and across testing sessions, as well as pupillometry indicators of listening effort and fatigue/alertness.

The expected outcomes are tools for reliably detecting small differences in speech-in-noise performance and listening effort that we ultimately expect to accompany future hearing interventions. A second outcome will be a better understanding of the role that low-gain hearing aids play in reducing the hearing difficulties of SMs. We intend for the results of this work to inform counseling, clinical decisions, and validation of treatments so that patients are provided the best hearing possible and to ensure Warfighter readiness for duty.