Complex sentence: It is said that only the words spoken by the actors were pre-recorded (on a disc, not on film); the other sounds-footsteps, closing doors, church bells-were conveyed live during the screening along with the musical accompaniment.
Split into simpler sentences: It is said that only the words spoken by the actors were pre-recorded (on a disc, not on film). The other sounds-footsteps, closing doors, church bells-were conveyed live during the screening along with the musical accompaniment.