Laminar separation bubbles in Low Reynolds number airfoils is important for several applications such as: gas turbines, wind generators, unmanned aerial vehicles, among others. The performance loss of this airfoils is usually associated with the presence and rupture of separation bubbles. The effects related to the sudden variation of the level of flow disturbances upstream of the bubble formation region are investigated in this work. The idea is to evaluate how the flow behaves when subjected to a sudden variation in the freestream turbulence. This condition can be observed in airfoil cascade of turbines, where the wake of a previous stage can influence the next. Although this scenario is of practical relevance, it has been poorly investigated in literature. For the present study, a water channel from the Fluids Engineering Laboratory was used. The pressure gradient, necessary for the bubble formation, was generated with a convergentdivergent plate and the level of disturbances in the boundary layer was controlled using a vibrating ribbon. Velocity fields in the bubble region were measured using the Particle Image Velocimetry technique with high temporal resolution. The generation of disturbances and measurements were phase locked, thus allowing the use of ensemble average techniques. The bubble was characterized in a so called steady regime, where there was no excitation of controlled disturbances upstream of the bubble. The results were compared with references in the literature, showing good agreement. In the transient regime, the flow was analyzed from the moment the disturbance generator was suddenly turned off until the bubble had completely recovered. In these conditions, it was noted that the bubble grew until reaching a length greater than that observed in the stationary regime. Only after the release of a large vortex did the bubble return to exhibit characteristics similar to those of the stationary regime. This behavior is similar to that reported in the literature for bubble rupture (bursting) but that is still not well understood.