Study provides new insight on hearing development in children

A new study from Oregon Health & Science University is the first to suggest that binaural pitch fusion —a process that involves merging different pitches from each ear into a single sound  — is one type of central hearing processing that may still be developing in pre-adolescent children and could present an opportunity for treatment. 

The study published last week in the Journal of the Association for Research in Otolaryngology.

Binaural pitch fusion is relevant to the “cocktail party effect,” or the brain’s ability to focus one’s attention and listen to a single person talking while filtering out other voices in the room. Individuals who experience what’s known clinically as “broad binaural fusion” are not able to effectively separate out these multiple voices, which can limit their ability to understand speech in noisy environments.

With better understanding of how and when this ability develops in children, clinicians may be able to develop more effective, practical interventions for broad binaural fusion in children with hearing loss and auditory processing disorders.

"What was very surprising is that we found that even the children with typical hearing had abnormal broad fusion, just like adults with hearing loss, and then over time their fusion became sharper and more mature,” said the study’s corresponding author Lina Reiss, Ph.D., professor of otolaryngology/head and neck surgery in the OHSU School of Medicine. 

“This indicates an extended timeline of auditory development in children, which has exciting scientific and clinical implications. We hope this will contribute to more effective interventions to support development of speech in noise perception in children.”

Understanding hearing, improving outcomes

Researchers measured and compared binaural pitch fusion changes among children of varying ages and developmental stages. After long-term follow ups, they then compared results of children with normal hearing to those with hearing loss, as well as to those with different hearing device combinations, such as a cochlear implant.

The study found that even children with typical hearing will have greater difficulties with speech perception in noise due to immature binaural fusion development. Findings demonstrated that binaural fusion sharpens significantly from 6 to 14 years old, indicating that binaural connections are still maturing and likely guided by hearing experience during childhood development.

Jennifer Fowler, Au.D., assistant professor of otolaryngology/head and neck surgery in the OHSU School of Medicine and co-author of the study, emphasized that identifying interventions to improve speech and noise recognition, even in children with typical hearing, has been shown to be important for developmental outcomes, including academic performance.

“We should be considering interventions to create quieter classroom environments for learning, such as providing microphone systems in a larger classroom, to ensure children can hear over background noise and from a distance,” Fowler said. “Music training has been shown to be an effective way to sharpen binaural fusion, so exploring how to create a music intervention for children in a clinical model could be beneficial for patients.”

Looking forward, researchers hope to identify ways to prevent the development of abnormally broad fusion and reduce its impacts with new or more targeted uses of hearing devices.

“If we can try to understand the biological structures that are involved in binaural fusion by looking closely at the brains of children during this development process,” Reiss said, “we will have a much better idea of how to improve it.” 

This study was supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health, under Award Number R01DC013307. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.