AKalmanfiltering(KF)approachtoon-linemusicalbeattrackingwithprobabilisticdataassociation(PDA)isinvestigatedinthiswork.Wefirstformulatethebeattrackingprocessasalineardynamicsystemofbeatprogression,andthenapplytheKalmanfilteringlgorithmtothedynamicsysteminestimatingthetime-varyingtemp