The stochastic resonance (SR) is a phenomenon discovered recently in some nonlinear systems where addition of a certain amount of noise can, somewhat paradoxically, enhance its performance. It has found applications in biological sensory systems [1] such as visual, auditory systems, and tactile system as well as engineering applications such as ac-driven Schmitt triggers, and bistable ring lasers. The bistable systems (BS) are nonlinear systems [4] that are widely used as SR systems.