Children who are hard of hearing are an under-researched population. What is the impact of early identification and intervention, as well as hearing aid technology, on outcomes for these children?
Any degree of hearing loss can put a child at risk for language delays. As a result, it is critical to conduct research that focuses on children with all degrees of hearing loss, including mild to severe. Surprisingly, research on children who are hard of hearing is rare. Most studies have been done with children with severe to profound hearing loss, even though this group only makes up a small proportion of children with hearing loss. Although research on children who are deaf is valuable, these findings are not directly applicable to children who are hard of hearing, most of whom rely on spoken language to communicate.
Since 2008, I have been a researcher on the Outcomes of Children with Hearing Loss (OCHL) study. The primary goal of the OCHL is to fill gaps in our knowledge regarding best clinical practices for these children. OCHL is a multicenter, prospective, longitudinal study. Researchers from multiple disciplines, including audiology, child language, psychology, linguistics, and biostatistics came together from the University of Iowa, Boys Town National Research Hospital, and the University of North Carolina-Chapel Hill. Over three hundred children with permanent, mild to severe bilateral hearing loss were followed for up to three years or more.
The primary goal was to investigate a new generation of early-identified children with hearing loss and address the following questions: What are the developmental outcomes for these children? Does inconsistent auditory access put them at risk for language delays?
The results from the first five years of the OCHL study have recently been published in a supplement to the journal Ear and Hearing. These articles are available via free public access on the OCHL webpage.
I recently presented our findings at the 18th Multidisciplinary Colloquium held by the GEERS Foundation in Berlin. Here is a video of that presentation:
To briefly summarize the major findings of the study, our team of researchers found that 1) children who are hard of hearing were at risk for language delays, 2) there were substantial individual differences in the quality of hearing aid fittings (measured via aided audibility) and amount of daily hearing aid use, with 35% of children being under-amplified relative to prescriptive hearing aid targets and infants averaging 4 hours of hearing aid use per day, and 3) aided audibility and consistently worn hearing aids provided protection against language delays, even in cases of later identification of hearing loss.
Aided audibility and amount of daily hearing aid use can be thought of as “malleable factors” — variables that are responsive to change as the result of intervention. These malleable factors can be addressed to maximize the outcomes of children who are hard of hearing. Audiologists can use real-ear measures to verify amplification and optimize aided audibility. Service providers can promote consistent hearing aid use with families, even in cases of mild hearing loss.
Our findings provide an optimistic view of the achievements that are possible for children who are hard of hearing, but the importance of early and effective interventions should not be underestimated. Future directions for the OCHL project include examining academic and literacy outcomes of children from the same cohort, to identify risk factors for academic achievement through the fourth grade.
As we follow these children into elementary grades, our findings will continue to inform parents, clinicians, and researchers about evidence-based practices for children who are hard of hearing.