A study published in August 2011 by researchers at the University of Pennsylvania showed that declines in hearing ability may accelerate gray matter atrophy in auditory areas of the brain and increase the listening effort necessary for older adults to successfully comprehend speech. The results hint at even greater benefits from hearing aids than simply improving hearing.

Hearing Aids May Help

"As hearing ability declines with age, interventions such as hearing aids should be considered not only to improve hearing but to preserve the brain," said lead author Jonathan Peelle, PhD. "People hear differently, and those with even moderate hearing loss may have to work harder to understand complex sentences."

In the studies, researchers measured the relationship of hearing acuity to the brain, first measuring the brain's response to increasingly complex sentences and then measuring cortical brain volume in auditory cortex. Older adults (60-77 years of age) with normal hearing for their age were evaluated to determine whether normal variations in hearing ability impacted the structure or function of the network of areas in the brain supporting speech comprehension.

The studies found that people with hearing loss showed less brain activity on functional MRI scans when listening to complex sentences. Poorer hearers also had less gray matter in the auditory cortex, suggesting that areas of the brain related to auditory processing may show accelerated atrophy when hearing ability declines.

Be Careful with that iPod

In general, research suggests that hearing sensitivity has cascading consequences for the neural processes supporting both perception and cognition. Although the research was conducted in older adults, the findings also have implications for younger adults, including those concerned about listening to music at loud volumes. "Your hearing ability directly affects how the brain processes sounds, including speech," says Dr. Peelle. "Preserving your hearing doesn't only protect your ears, but also helps your brain perform at its best."

The research appears in the latest edition of The Journal of Neuroscience and was funded by the National Institutes of Health.

The original press release appeared at http://www.uphs.upenn.edu/news/News_Releases/2011/08/mild-hearing/ and the full article is available here: http://www.jneurosci.org/content/31/35/12638.full.pdf+html