Noise improves balance

Whether it is squelching the hiss from a stereo speaker or tuning out the static from a television speaker, engineers are usually trained to fight noise wherever they find it. But some engineers are adding noise to one complex control system and making it work better.

The control system in question is the neurological one that keeps us standing upright. The brain and spinal cord integrate data from eyes, inner ears, muscles, and skin to send the proper commands to the muscles that keep us standing. Using a phenomenon called stochastic resonance, researchers at Boston University and Afferent in Providence, RI, have found a way to boost the flow of data to the brain and improve balance.

Stochastic resonance is found in certain systems (sensory neurons are one) that have a built-in threshold of activation. Mechanical systems too weak to cross the threshold are not felt. But an imperceptible amount of noisy vibration can make the signals felt. "Just the right amount of noise provides the pedestal upon which signals can ride over the threshold" and be felt, write Boston University's James J. Collins and Attila A. Priplatta and Afferent's Jason D. Harry and James B. Niemi in the April issue of IEEE Spectrum.