Principal Investigator: Kristin Uhler, PhD, CCC-A, PASC

Title: A novel method for improving bone conduction auditory brainstem response measures in infants

Abstract: Over twenty years ago, in the United States, Universal Newborn Hearing Screenings began, which has led to improved habilitation of infants and young children with hearing differences. These improvements have led to most children with hearing loss entering school with language within two standard deviations of their normal-hearing peers. However, there continues to be significant variability in outcomes of children with hearing loss; accurate audiologic assessment contributes to better outcomes. One challenge that persists is the accurate diagnosis of hearing loss (for example, the identification of conductive versus sensorineural pathology) which is key to effective intervention (e.g., the type of hearing aid fit and the amount of gain provided versus a cochlear implant).

During early infancy, an electrophysiology measure known as the auditory brainstem response (ABR) test assesses hearing abilities. Because screening for and identification of hearing loss is only as effective as the tools available for diagnosis, improved tools can lead to improved detection and classification of hearing loss and improved treatment outcomes. Improved accuracy of bone conduction testing is key to making sure infants receive the right type and programming for their hearing aids. Until this is done, children with hearing loss will continue to be at risk for poorer access to spoken language during a critical period of language development. We will test a novel method to reduce artifact in bone conduction testing, which is how clinical audiologists diagnose the type of hearing loss. We will compare the currently used bone conduction transducer, and MuMetal shielded bone conduction transducer to compare the differences in the artifact.

We hypothesize that testing with the shielded bone conduction oscillator will reduce stimulus artifact and improve the accuracy of bone conduction thresholds measured via ABR testing in infancy (1-5 months of age). We will utilize a within-subjects design to test aim 1 to compare artifacts between the shielded and unshielded bone conduction transducers. Next, we will quantify differences in waveform identification among audiologists for the shielded versus unshielded transducer. In aim 2, we will validate the accuracy of the ABR test measured during early infancy by having participants who were tested in aim 1 return for behavioral testing six months later. We will examine the threshold differences measured via ABR versus behaviorally. Differences of less than 10 dB HL at two or more frequencies will be considered good test-retest reliability. Poor reliability would result in poor hearing aid fittings and, in turn, poorer access to spoken language. The long-term goal of this research is to improve the sensitivity of diagnostic tools for ABR assessment to improve the accuracy of interventions. Improved habilitation strategies are highly relevant to the Department of Physical Medicine and Rehabilitation mission.