By Julia Campbell, Ph.D., Au.D.
Cortical auditory evoked potential (CAEP) gating current density reconstructions, with yellow illustrating the most likely area of activation. Credit: Campbell et al./Journal of Speech, Language, and Hearing Research
Typically developing children with typical hearing have more difficulty understanding speech in background noise than typical-hearing adults. This difference may be due to development of the central auditory pathways, as peripheral audition, which is measured with usual hearing evaluations, does not differ between children and adults, and the timelines between central auditory development and speech perception-in-noise (SPiN) ability are similar. For instance, children around the ages of 10 to 12 years begin to have adult-like SPiN skills, an age at which central auditory systems also begin to become adult-like.
One central auditory function that is also developing during this period is sensory gating. Sensory gating acts as an automatic “filter” that may suppress noise before reaching levels of attention. Indeed, my team and I have previously found that typical-hearing adults who struggle in background noise also tend to have worse gating function. Therefore, the development of gating may contribute to maturational trends in SPiN.
With this in mind, we measured sensory gating function in adults ages 22 to 24 years and children ages 5 to 8 years using cortical auditory evoked potentials recorded via high-density electroencephalography. From this data, we were able to model the cortical gating response in both the children and adults, showing distinct developmental central auditory networks. Our results appeared in the Journal of Speech, Language, and Hearing Research in January 2023.
We also measured SPiN ability using a clinical measure, the BKB-SiN, which provides the signal-to-noise ratio necessary to correctly perceive 50 percent of the words in given sentences. While both SPiN and gating function were significantly decreased in children, there was no significant relationship between gating function and SPiN in the children.
When these results are considered with our previous, similar study conducted in typical-hearing adults with SPiN ability ranging from typical to moderate deficits, it may be the case that sensory gating only underlies clinical SPiN deficits. For instance, the child group in our 2022 study, while having decreased SPiN ability, still performed within age-appropriate limits. Similarly, in the adult group in our 2020 study, there was no correlation between gating function and SPiN ability when performance was within typical limits.
In other words, worse gating appears to be a significant factor only when SPiN performance is outside of typical limits. In future studies, we aim to examine sensory gating function in typical-hearing children with clinically low SPiN outcomes. This study is important because faulty gating mechanisms, also observed in tinnitus and hearing loss, appear to play a role in auditory disorders.
Julia Campbell, Ph.D., Au.D., CCC-A, FAAA, is an assistant professor of communication sciences and disorders in the Central Sensory Processes Laboratory at the University of Texas at Austin. Campbell’s 2016 Emerging Research Grant was generously funded by the Les Paul Foundation.
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