Squeaking at soft–rigid frictional interfaces

Nature

by Adel Djellouli

February 26, 2026

AI-Generated Deep Dive Summary

Squeaking sounds are ubiquitous in our daily lives, from shoes on floors to squealing brakes. A recent study delves into why these noises occur when a soft material slides over a rigid one. Previous research focused on slow sliding without squeaking, but this new investigation examines faster speeds where squeaking happens. The findings reveal that stick-slip oscillations cause the noise, with geometric features like ridges influencing the frequency and coherence of the sounds. The study uses high-speed imaging and acoustic analysis to show that opening slip pulses propagate at shear wave speeds, creating irregular emissions in flat samples. However, introducing thin ridges confines these pulses, leading to consistent frequencies matching musical notes. This mechanism stabilizes frictional rupture, offering insights into natural phenomena like earthquakes and engineered surfaces. Understanding this mechanism is crucial for fields such as biomechanics and materials science. It can help reduce noise in devices and improve safety in machinery. The research highlights the importance of geometry in controlling dynamic interactions between materials, with broader implications for engineering and geology. The study's innovative approach bridges laboratory findings with real-world applications, emphasizing the role of surface features in modulating frictional dynamics. This knowledge could lead to advancements in designing quieter, more efficient systems across various industries

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Originally published on Nature on 2/26/2026