Sound created possibilities that silence never could. Musicals became the first uniquely sound-dependent genre — Busby Berkeley's geometric dance spectacles could not exist without synchronized music. Film noir relied on voice-over narration and the crack of gunshots. Screwball comedy depended on rapid-fire dialogue delivery.

Sound also turned the film score into a storytelling tool rather than live accompaniment. A composer could now lock music to the exact frame of an action, building tension or release that the audience felt without ever noticing the technique.