That study is ongoing, but Dr. Kraus realized in the meantime that she possessed a wealth of baseline data about the brains and sound-processing abilities of fit, young athletes and other students. She could crosscheck their brain wave readouts, she thought, and see if the athletes, when healthy, processed sounds differently than the other students.

So, for the new study, which was published this month in Sports Health, she did just that. And she found that the athletes did hear and make sense of sounds differently than most of us.

According to their electrical readouts, almost all of them attended to specific, specified sounds better than the other students. When the “da” syllable played, their brain waves jumped more than the other students’.

What interested and surprised Dr. Kraus, though, was that the athletes’ brains could focus on the “da” sound so well because they had filtered out more background noise beforehand than other students. Their brain wave response to the kind of constant, murmurous aural clutter around us was lower than among the other students, allowing the athletes to better amplify and pinpoint the sound they wanted.

“Basically, their brains were quieter,” Dr. Kraus says.

Some of the athletes’ acoustic agility most likely developed during years of attending to crucial sounds despite clatter, Dr. Kraus says. “You have to be able to hear the coach yelling something or what a teammate is saying,” she says. “Brains change in response to that kind of repeated experience,” and the sound-processing components within the brain strengthen.

But many of the athletes played sports that, typically, are not noisy, she points out. Cross-country running and golf, for instance, most likely demand less sound filtering during most practices and competitions than a sport like football or basketball. But the university’s runners and golfers had brains just as quiet as those of linemen.

For them, “fitness and regular movement of the body also change the brain,” Dr. Kraus says. And sports that seem quiet can still demand a focus on subtle sounds and signals, like the whoosh of a breeze through branches alerting golfers and runners to wind speed or a creak in a joint that could warn of early injury.