A team of researchers from Massachusetts Eye and Ear have found a correlation between the difficulties of understanding speech in noisy environments with a condition commonly known as hidden hearing loss, which is experienced in college-age young adults with normal hearing sensitivity.
The research team, led by Stephane Maison, Ph.D., discovered an important link between performance on a speech-in-noise test and an electrophysiological measure of the health of the auditory nerve. The team also witnessed significantly better results on both tests among subjects who consistently wore hearing protection when exposed to loud sounds.
“While hearing sensitivity and the ability to understand speech in quiet environments were the same across all subjects, we saw reduced responses from the auditory nerve in participants exposed to noise on a regular basis and, as expected, that loss was matched with difficulties understanding speech in noisy and reverberating environments,” said Dr. Maison, an investigator in the Eaton-Peabody Laboratories at Mass. Eye and Ear.
An estimated 48 million Americans are affected by hearing loss, normally caused by noise or aging. It usually occurs when there’s damage to the sensory cells of the inner ear (or cochlea). The cochlea is responsible for transforming sounds into electrical signals, and the auditory nerve fibers transfer those signals to the brain.
The researchers found that diagnostic measures for hidden hearing loss in young adults were important, because it helped them see the degree of noise-induced damage to the inner ear.
“Establishing a reliable diagnosis of hidden hearing loss is key to progress in understanding inner ear disease,” said Dr. Maison. “Not only may this change the way patients are tested in clinic, but it also opens the door to new research, including understanding the mechanisms underlying a number of hearing impairments such as tinnitus and hyperacusis.”
Day, S., “Researchers find evidence of “hidden hearing loss” in college-age human subjects,” Massachusetts Eye and Ear web site, Sept 12 2016; http://www.meei.harvard.edu/news/press-releases/2016/09/researchers-find-evidence-of-hidden-hearing-loss-in-college-age-human-subjects.