Higher Fitness Linked to Better Speech-in-Noise Performance in Early Study

People with higher cardiorespiratory fitness performed better on tests of understanding speech in noisy environments in the first phase of an ongoing Northeastern University study. The early finding suggests a possible relationship between physical fitness and the brain’s ability to manage competing sounds, but it does not establish that exercise caused the difference.

Researchers in Jonathan Peelle’s laboratory measured participants’ VO2 max, a marker of cardiorespiratory fitness, as volunteers ran on a treadmill while wearing masks that tracked oxygen consumption. The participants also repeated recorded sentences presented against different levels of background noise—a type of speech-in-noise task designed to assess how well someone can separate a target voice from other sounds.

According to Peelle, participants with higher fitness levels have so far performed about 15% better than their less-fit counterparts. He described the difference as roughly one or two additional words per sentence, which can provide more context during a conversation.

The study focuses on a challenge that involves more than simply increasing volume. In a crowded restaurant or other noisy setting, listeners must identify the relevant speech signal, maintain information in working memory and respond appropriately. Earlier research from Peelle’s group found that difficult speech processing engages the prefrontal cortex, a brain region involved in executive functions such as managing information, switching between tasks and making decisions.

The preliminary result is consistent with other research discussed in the report linking aerobic exercise with cognition, including attention and working memory. However, Kirk Erickson of AdventHealth cautioned that the relationship between fitness and speech perception may be correlational. Higher fitness could be associated with better performance without fitness itself being the cause, and the neurological explanation remains unresolved.

The next stage will test whether a single 20-minute vigorous treadmill session produces an immediate change in speech-perception performance. That experiment is intended as a prototype for a planned six-month intervention involving regular workouts. Peelle said the longer-term goal is to develop the work into a clinical trial focused on functional communication.

The researchers also plan to use functional near-infrared spectroscopy, or fNIRS, to examine brain activity during listening. The technology uses changes in blood flow to track activity and can be used in more natural environments than an MRI scanner, potentially allowing researchers to study speech perception in settings such as a noisy coffee shop.

At this stage, the study has identified an early association rather than a demonstrated treatment effect. Its upcoming exercise and brain-imaging phases are intended to test whether the relationship is causal and to investigate how fitness might relate to the cognitive demands of listening in noise.