Stochastic Resonance
Lav R. Varshney

Abstract-Noise is usually considered a nuisance.  In many nonlinear systems, however, noise actually enhances performance, for example in the detection of weak signals.  This phenomenon, stochastic resonance, is a cooperative effect between a signal and noise and in its most classical form involves a small periodic influence entraining external random noise.  Stochastic resonance has been found in many physical and biological systems including the Earth’s ice age periodicity, the Schmitt trigger, the ring laser, mechanoreceptor hair cells of crayfish, the cercal system of the cricket, and human visual processes.  Although stochastic resonance has been seen mainly in dynamical systems, it also occurs in nondynamical systems such as threshold detectors and quantizers.  The peak detection performance of sinusoids in the presence of noise with a threshold detctor rises quickly as a function of noise level, and then subsides gradually after the peak noise level is reached.  This stochastic resonance effect is also shown to occur in a system with coupled threshold detector and human visual system.  The detection performance is enhanced with temporal integration of independent looks.