 A few innovative commercial directors immediately saw the ways in which sound could be employed as an integral part of cinematic storytelling, beyond the obvious function of recording speech.In "Blackmail", Hitchcock manipulated the reproduction of a character's monologue so the word "knife" would leap out from a blurry stream of sound, reflecting the subjective impression of the protagonist, who is desperate to conceal her involvement in a fatal stabbing.In his first film, the Paramount "Applause" (1929), Rouben Mamoulian created the illusion of acoustic depth by varying the volume of ambient sound in proportion to the distance of shots.