Hearing loss diminishes a person’s speech perception, particularly when they are in busy settings. It is less known, however, as to why some people with normal hearing also experience difficulties with speech perception in noise (SPiN).
Some of the things that influence the ability of SPiN in adults who have normal hearing are top-down cognitive functions of attention, restriction and working memory. Restriction in the cognitive level could be considered as the capacity to suppress background noises in order to comprehend speech.
Research on Sensory Inhibition to SPiN in Those with Healthy Hearing
Inhibition of background noises exists at a bottom-up, sensory stage as a natural process. It functions, even while the listener is not fully paying attention. At this level, it’s viewed as fencing in sensory information that leads to cognitive centers. A lack of sensory inhibition might lead to an overload of auditory noise to reach cognitive centers, which can destroy these resources and cause a weak SPiN performance.
In a study conducted by Julia Campbell, Ph.D., Au.D., CCC-A, FAAA, an assistant professor of communication sciences and disorders in the Central Sensory Processes Laboratory at the University of Texas at Austin, she and her colleagues wanted to discover whether sensory inhibition correlated to SPiN ability in people with healthy hearing and identify hidden cortical inhibitory networks in this group.
Test subjects were asked to view a silent film while being presented with identical sound pairs. They were instructed to not pay attention to the sound. Participants who had typical sensory gating, or inhibitory function, should display a large suppression and latency decrease of the CAEP S2 response compared to the CAEP S1 response as the repetitive sound is perceived as non-novel.
They found this predicted response in participants who had typical SPiN, but not in participants who had mild SPiN deterioration, which was consistent with reduced sensory inhibition in this group.
Campbell and her colleagues also noted that listeners who had mild SPiN deficits had atypical cortical inhibitory networks that underlie the gating response, which affected prefrontal, frontal and parietal cortical regions.
All of these results indicated that people with normal hearing and mild SPiN damage might have decreased inhibition in the sensory level. This has shown that there is an insufficient and abnormal activation of cortical inhibitory networks.
This absence of sensory inhibition might provide unnecessary noise to reach cognitive centers and impede speech perception.
If you have difficulty with understanding speech, or if you, or others, are noticing that your own speech is slurred, please contact us at Pure Sound Hearing for a free hearing test and consultation. We offer a variety of hearing aid brands including HANSATON, Oticon, Phonak, ReSound, Rexton, Signia, Starkey, Unitron and Widex.
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