Harvard boffins crack the mystery of squeaky sneakers

"The results showed that the squeaking sound is produced by wave-like patterns across the rubber surface, contacting and then releasing from the glass, allowing the sliding between the surfaces. The waves move across the interface between the two materials at a speed of nearly 300 kilometers per hour."

"In flat samples, these pulses are irregular and generate broadband acoustic emissions. Introducing thin surface ridges confines pulse propagation, yielding a consistent repetition frequency matching the first shear mode of the sliding block and squeaking at that frequency."

Researchers at Harvard University discovered that the squeaking sound produced by sneakers on basketball courts originates from wave-like patterns across the rubber surface that contact and release from the court surface during sliding. Using experimental analysis with rubber blocks sliding against glass plates and high-speed cameras, they found these waves travel at nearly 300 kilometers per hour. The study revealed that ridges on sneaker soles, similar to actual shoe treads, significantly affect sound production by confining pulse propagation and creating consistent repetition frequencies. This finding contradicts the long-held stick-slip phenomenon explanation previously attributed to the sound.

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