Spanning from 1918 to 1960, Fritz Lang’s oeuvre reflects the evolution of film style and technology over several crucial stages in the art form’s history. Among the game-changing developments that the master helped pioneer was the inventive use of sound in the early years of the talkie. Lang’s expressionistic 1931 thriller M, widely considered his greatest achievement, employed innovative techniques to tell the story of a serial killer who preys on children and the hysteria that engulfs the streets of Berlin as the police begin their search for him. For the latest episode of Observations on Film Art, a series that explores how the world’s greatest filmmakers deployed the elements of the medium, Professor Kristin Thompson delves into four of Lang’s sonic devices, which heighten the suspense of the narrative and proved influential to a generation of filmmakers making the transition to sound cinema. Watch a preview of the episode below, then head to the Criterion Channel on FilmStruck to watch it in its entirety alongside our edition of M.