By Viji Easwar, Ph.D.
In infants and children too young to participate in hearing tests, using neural responses to sound is a reliable way to assess how well they hear. Neural responses to sound are routinely used in audiology clinics for diagnosis to infer the degree and type of hearing loss in very young babies and in older children who may have additional developmental challenges.
Neural tests to assess if important speech elements are heard could be equally useful in children and adults.
However, the use of neural responses to sound to infer how well hearing aids—a common first form of intervention—provide access to speech is less well established. Such tests with hearing aids require the use of speech so hearing aids function the way they would during everyday conversations.
We have been working toward a clinical test that plays the word “susashee” and records neural responses tagged to each sound. The sounds are chosen and modified such that neural responses can help us infer whether low, mid, and high frequencies are accessible to the listener with or without hearing aids, and the extent to which hearing aids make each of these frequencies accessible to the listener.
Hearing all these frequencies are critical for speech understanding and speech and language development during early years of life during which rapid brain development occurs. Our previous work has shown that such a neural test could be useful to assess access to speech in adults with hearing loss using hearing aids, and can be measured in young infants in their sleep.
In our recent study funded by Hearing Health Foundation and published in the Journal of Speech, Language, and Hearing Research in October 2022, we assessed whether neural responses could predict audibility and inaudibility of low, mid, and high frequency speech played at soft to loud levels in children ages 5 to 17 as accurately as in adults, and whether analysis of neural responses using different statistical metrics can influence its accuracy.
Our results demonstrate that neural tests are equally accurate in children and adults, and the type of analysis did not influence accuracy in children. Accuracy of predictions increased at high frequencies, but this was similar in both adults and children.
Further, in a parallel study published in the Journal of Association for Research in Otolaryngology in August 2022, we were able to confirm that the same analysis features pertaining to neural response delays could be used in children and adults without substantial impact on estimation of such responses. We are currently evaluating the accuracy of this neural test in children with hearing loss with and without hearing aids, and advancing our analysis strategies to improve the accuracy of predictions for clinical use.
A 2019 Emerging Research Grants scientist funded by the Children’s Hearing Institute, Viji Easwar, Ph.D., is the lead researcher of the pediatric hearing research program at the National Acoustic Laboratories in Sydney, Australia.
Applications are now open for the 2023-2024 Emerging Research Grants cycle. See hhf.org/how-to-apply for more information.
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Babies are too young to do hearing tests until 8 to 10 months of age, and at such young ages, tracking brain waves to sounds is the only reliable way to assess hearing.