In rhythmic montage, the action within the frame is emphasized by the time given to each shot. The rhythm of the montage can conflict with the rhythm of movement within the frame, thus generating tension.
Eisenstein made The Battleship Potemkin in the era of silent movies. Even so, his montages often fit a rhythmic pattern that could be described as musical. Watch this clip from Potemkin, in which mutinous sailors are put before a firing squad. Note the rhythm of this sequence, and how it is emphasized by the hand movements of the priest with his cross and of the officer on his sword.