The most common causes of hearing loss — age and excessive noise — have different effects on sound processing in the ear, reports a new study in The Journal of Neuroscience. This finding may explain different levels of speech perception impairment between individuals with similar clinically measured sensitivity loss, and suggests each type of hearing loss should have its own unique treatment.
The study, led by Kenneth Henry, Ph.D., assistant professor in the University of Rochester Medical Center’s Departments of Otolaryngology and Neuroscience, and Michael Heinz, Ph.D., professor in Purdue University’s Departments of Speech, Language and Hearing Sciences and Biomedical Engineering, used an animal model of age-related hearing loss to observe changes in how the auditory nerve encodes complex sounds. Comparing their results to data from a noise-induced hearing loss animal model, the researchers found that the same level of sound sensitivity loss from aging causes less severe damage to auditory-nerve coding than noise-induced hearing loss. Additionally, mild noise-induced hearing loss caused the same levels of processing damage as moderate to severe age-related hearing loss.
These results indicate a need for heightened hearing-safety awareness, since noise-induced hearing loss is more severe yet completely preventable, as well as for precision medicine approaches in audiology.
This research was supported by grants from the National Institute on Deafness and Other Communication Disorders, the UK-US Fulbright Commission Scholarship Award funded by Action on Hearing Loss.