Abstract: Most comprehensive speaker verification systems use background speakers to model imposters.Based on analysis of general background speaker models,a new model combining the universal background model(UBM) with a cohort model is proposed.In the proposed speaker verification system,the same UBM is set for all claimed speaker,and a cohort model is set for each speaker.When the UBM fails to give a definite decision,the cohort model is used to make a verdict.The new background speaker model takes advantages of both UBM and the cohort model.Experimental results show that an equal error rate lower than conventional techniques is obtainable.