Balancing Act
Noise is the key to restoring the body’s sense of equilibrium
By Jason D. Harry, James B. Niemi, Attila A. Priplata & James J. Collins
(Posted on IEEE SPECTRUM Online, April 2005)
Balancing Act


STILL STANDING: Using a phenomenon called stochastic resonance, the human body can make use of random vibrations to help maintain its balance. In experiments on people in their 20s and people in their 70s, actuators embedded in gel insoles [see photo, "Vibrating Soles"] generated noisy vibrations [above] with such a small amount of force that a person standing on the insoles could not feel them. A reflective marker [not shown] was fixed to the research subject’s shoulder, and a video camera recorded its position.
People always sway a small amount even when they are trying to stand still [orange line, top]. And the amount of sway increases with age. But under the influence of a small amount of vibration, which improves the mechanical senses in the feet, both old and young sway much less [blue line]. Remarkably, noise made people in their 70s sway about as much as people in their 20s swayed without noise.
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