4 min readNew DelhiUpdated: Feb 26, 2026 08:24 PM IST
Anyone who has watched a basketball game knows the sound. The sharp squeak of rubber sneakers sliding across a polished court is almost as constant as the bounce of the ball. That same high-pitched noise can also be heard in screeching car tyres, old bicycle brakes, and even windscreen wipers. Now, scientists say they finally understand what causes it, and the answer could have implications far beyond sports arenas.
In a new study published in Nature on February 25, researchers describe a previously unseen behaviour in friction that explains why sneakers squeak. The team, led by materials scientist Adel Djellouli at Harvard School of Engineering and Applied Sciences, set out with a simple question: why do basketball shoes make that distinctive noise?
Scientists have long known that squeaking comes from what is called “stick-slip” friction. This happens when two surfaces briefly stick together and then suddenly slip apart, over and over again. These rapid cycles create vibrations in the air, which we hear as sound.
But Djellouli’s team found that this explanation was only part of the story.
Using high-speed cameras capable of recording up to one million frames per second, the researchers closely observed how rubber sneaker soles moved across a glass surface. They also used imaging tools to track the exact points where the rubber touched the glass. Sensitive instruments measured each tiny sound produced during the sliding motion.
What they discovered surprised them.
Instead of random stick-slip movements, the squeaks were driven by repeating slip pulses moving through the material. The pitch of the sound depended on how quickly these pulses repeated. That repetition rate was influenced by the rubber’s stiffness and thickness.
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In short, the design of the shoe plays a direct role in the noise it makes.
Shape matters more than expected
To test their findings further, the team experimented with simple rubber blocks pressed against glass. When the blocks had flat edges, the sounds changed. The noises became more irregular and produced softer, swishing tones rather than sharp squeaks.
This proved that geometry, the exact shape and surface features of the rubber, strongly affects how friction behaves.
Study co-author Gabriele Albertini from the University of Nottingham said the results challenge older models that treated friction as a simple, one-dimensional process. Even tiny surface details can reorganise the motion in unexpected ways.
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From sneakers to earthquakes
The research even took a playful turn. After learning how to control the slip pulses, the scientists arranged rubber blocks of different heights and manually recreated a tune, including the famous theme associated with Darth Vader from Star Wars.
But beyond novelty, the findings could have serious applications. Engineers have long wanted to design materials with adjustable friction surfaces that can switch between high grip and smooth glide when needed.
The study may also help scientists better understand earthquakes. Similar slip pulses occur when tectonic plates shift along fault lines. Physicist Shmuel Rubinstein noted that the physics behind a squeaking shoe can resemble the rapid ruptures seen in seismic events.
In other words, the same forces at work on a basketball court may echo deep beneath the Earth’s surface.
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While the squeak of sneakers may never disappear entirely, scientists now have a clearer understanding of why it happens and how to control it.
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