You can’t talk about Robert Bresson for long before his use of sound comes up. His stripped-down masterpieces are memorable for the way they engage the ear as well as the eye. A Man Escaped, out this week on Blu-ray and DVD, is an especially rich aural experience, as film scholars David Bordwell and Kristin Thompson explain in a new visual essay, which sets clips from the film to a reading (by actor Dan Stewart) of ”Functions of Film Sound,” a chapter from their book Film Art: An Introduction. Here are the first few minutes of the essay, which establish the environment of Bresson’s classic prison-escape film and discuss his fascinating use of nonsimultaneous audio commentary. The whole thing can be seen on the discs.