Harvard Study Explains Sneaker Squeak Physics

A Harvard University materials scientist, inspired by the persistent squeak of sneakers during a Boston Celtics basketball game, has uncovered the physics behind the familiar sound through a new study. Adel Djellouli and his colleagues detailed their findings in the journal Nature, revealing how rapid ripples in a shoe's sole generate the high-pitched noise as it grips the floor.

The research began last year when Djellouli attended a game at TD Garden in Boston. Amid the roar of the crowd, the constant squeaking of players' shoes as they jab-step, pivot, and defend caught his attention. "This squeaking sound when players are sliding on the floor is omnipresent," Djellouli said. "It's always there, right?" Curious about the mechanism, the scientist returned to his lab at Harvard's School of Engineering and Applied Sciences to investigate.

In controlled experiments, the team slid a sneaker sole across a smooth glass plate, simulating the hardwood courts of a basketball arena. They captured the action using a high-speed camera and recorded the sounds with a microphone. The footage showed tiny sections of the rubber sole deforming and momentarily detaching from the surface before...