Fitter People May Understand Speech Better in Noisy Rooms, Early Study Suggests

Physical fitness may give the brain an edge when it comes to understanding speech in noisy environments, early results from an ongoing study at Northeastern University suggest. "By age 80, something like 80% of adults will have hearing loss," said Northeastern Bouvé College of Health Sciences professor Jonathan Peelle. But hearing loss is not only about volume: untangling speech from other sounds and remembering what was said also depends on the brain, not just the ears.

Peelle's earlier research showed that parsing speech in noisy conditions engages the prefrontal cortex, a brain region that handles executive functions such as managing information and switching between tasks. This region is particularly vulnerable to age-related damage, and no hearing aid can fix a neurological problem. Because aerobic exercise is known to support brain health, Peelle and PhD student Bridget Carey set out to test whether it could also benefit speech perception.

In the study's first phase, volunteers ran on a treadmill while wearing masks that tracked their oxygen consumption to determine VO2 max, a measure of cardiorespiratory fitness. They also completed a test in which they repeated recorded sentences played against varying levels of background noise. So far, participants with higher fitness levels are performing about 15% better on these speech-in-noise tasks than their less athletic counterparts. "It may not sound like a ton, but that's one or two words per sentence more that you're able to get, which means you can get more context," Peelle said.

Brian Sandroff of the Kessler Foundation's Center for Neuropsychology and Neuroscience Research said working memory and attention, the processes involved in speech-in-noise tasks, benefit from "even a single bout of aerobic exercise." Kirk Erickson of AdventHealth cautioned that the correlation between fitness and speech perception does not by itself prove exercise causes the improvement through a neurological mechanism.

In the next phase, subjects will exercise vigorously on a treadmill for 20 minutes and then have their speech perception tested, serving as a prototype for a planned six-month intervention involving regular workouts. Peelle and Carey also plan to use functional near-infrared spectroscopy, a portable brain-imaging technology, to look for the neural bridge between fitness and hearing directly.