The ratio of signal to noise (SNR) reaches to the maximum under an optimize strength of noise, and SNR is decreased while strong noise overwhelms signal.

• 当给予系统低幅值的阈下信号时，在噪声的参予下，系统对此阈下信号的检测能力增强，其间有一最优化强度的噪声可使系统的信噪比(signal-noise-ratio, SNR)最大，这就是随机共振现象(stochastic resonance, SR)。