In this paper, I have shown how to associate a musical beat with a note within the framework of Optimality Theory. And the following hierarchy of constraints is suggested to associate a sub-beat with a note. Alternation Sub-beat CCC Head $gg$ Beat-to-Note $gg$ Note-to-Beat EQ-Beats Smaller Note Furthermore, I have tried to explain Sprung Rhythm with a musical beat system. I have suggested the following hierarchy for Sprung Rhythm. Head $gg$ SCSR Using a sub-beat on the basis of Head $gg$ SCSR shows the abrupt change of Sprung Rhythm well.