An expert on orientation and mobility for the blind, William R. Wiener, dean of graduate studies at the University of North Carolina, Greensboro, said that sound localization “is so important when blind people navigate the world,” and added, “Listening to the ball, locating where it is and swinging at it probably helps you with the sport and also with your mobility.”

Blind tennis is made possible, scientists say, by the adaptability of the human brain — which appears to repurpose its visual area, the occipital cortex, to process sound and touch in response to blindness.

A series of studies discovered activity in the visual cortex when blind test subjects read Braille, and found that a blind woman could no longer make sense of the raised dots after suffering an occipital stroke. Another study, of sighted subjects who were blindfolded, showed that the occipital cortex began processing tactile and auditory information within five days.

“How it works is not a mystery,” said Melvyn A. Goodale, director of the Brain and Mind Institute at the University of Western Ontario. “We know that it is possible to localize sounds, and it is likely that the blind get better at this than sighted people.”

Dr. Goodale and his colleagues are studying how echo processing works in the occipital cortex of blind echolocation experts like Daniel Kish, who as a baby lost his sight to retinoblastoma. Human echolocators use palatal clicks or hand claps to “see” objects around them, like sonar in bats, only bats use ultrasonic frequencies that can resolve flying insects. This skill allows Mr. Kish to hike along cliff edges and ride a mountain bike.