System and method for managing a virtual adapter instance associated with a physical adapter is provided. Degraded speech is preprocessed in a speaker identification process to produce SID usable and SID unusable segments. The metal oxide thin film has voids which are formed inside the metal oxide thin film to scatter light. Voltages are selectively applied to the liquid crystal layer of the pixel portion and that of the background portion, and thereby the transmission, diffusion, or absorption of the light incident on the liquid crystal layer is arbitrarily varied to conduct display.