Physical fitness may improve speech understanding in noise in older adults

About 80% of adults may experience hearing loss by age 80, says Jonathan Bell, a professor of health sciences at the Bovey College of Health Sciences at Northeastern University. But the problem is not limited to low volume, as some people have difficulty separating speech from surrounding sounds, especially in crowded places such as restaurants.

Understanding speech in noise is linked to mental processes that include attention, working memory, and executive functions, which are functions that depend largely on the prefrontal cortex in the brain, and may be affected by aging.

Building on the known relationship between physical activity and brain health, Bell and researcher Bridget Carey began studying whether physical fitness could also help improve speech understanding.

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In the first phase, the researchers measured the cardiorespiratory fitness of volunteers using a maximum oxygen consumption test (VO2 max), and then subjected them to tests in which they were asked to repeat recorded sentences amid different levels of noise.

Preliminary results showed that the most fit participants achieved about 15% better performance in understanding speech in noise compared to the less fit.

Picking up an extra word or two in each sentence may give the person more context and help them follow the conversation, Bell says.

But researchers stress that these results do not prove that physical fitness is the reason for the improvement. Kirk Erickson, a researcher at the Advent Health Hospital Network, points out that fitness may help the brain use its cognitive resources more efficiently when listening becomes more difficult.

In the next stage, participants will undergo a 20-minute exercise session on a treadmill, and then their ability to understand speech will be retested to see if physical activity leads to direct improvement. The results will pave the way for a longer intervention lasting six months.

The researchers also plan to use functional near-infrared spectroscopy (fNIRS) to monitor brain activity during listening in real, noisy environments.

Bell hopes that this research will eventually lead to interventions that help people improve their ability to communicate and understand speech in their daily lives.