Sound film
The primary steps in the commercialization of sound cinema were taken in the mid- to late 1920s. At first, the sound films which included synchronized dialogue, known as "talking pictures", or "talkies", were exclusively shorts. The earliest feature-length movies with recorded sound included only music and effects. The first feature film originally presented as a talkie was "The Jazz Singer", released in October 1927. A major hit, it was made with Vitaphone, which was at the time the leading brand of sound-on-disc technology. Sound-on-film, however, would soon become the standard for talking pictures.
Filmmaking technique of Luis Buñuel
Buñuel has been hailed as a pioneer of the sound film, with "L'Age d'Or" being cited as one of the first innovative uses of sound in French film. Film scholar Linda Williams has pointed out that Buñuel used sounds, including music, as nonsynchronous counterpoint to the visual image, rather than redundant accompaniment, in accordance with theories that had been advanced by Sergei Eisenstein and others in a 1928 manifesto on the sound film. Critic Marsha Kinder has posited that Buñuel's years as a film dubber in Europe and Hollywood put him in the position of "mastering the conventions of film sound, to subvert them more effectively". In his later years, Buñuel was almost completely deaf, but he continued to assert control over the sound effects in his films, such as "The Discreet Charm of the Bourgeoisie", in which seemingly important speech, especially political discourse, is often drowned out by the noise of urban life, in such a systematic manner that Kinder has identified Buñuel as one of the first professional sound designers in cinema. As further illustration of this, scholar Sally Faulkner has described the means by which, in his film "Tristana", Buñuel "engineers a kind of figurative deafness, or disability, in the spectator" in scenes which involve deaf characters, by, for example, combining the sound of gushing water with an image of a stagnant pool, or exaggerating the volume level of chiming bells.