Rear Window (1954) employed an iconically unique tactic to validate the authenticity of the large production set being an actual apartment courtyard. All of the sound in the film, save for the orchestration at the opening and closing of the piece, is diegetic, natural location noise. The only in-film music is slowly composed by one of Jeff’s (James Stewart) neighbors, a tactful method for imposing soundtrack in an organic fashion. It almost never parallels with the action Jeff is seeing at the time, because it shouldn’t.

Rear Window was the first instance of this diegetic approach in a film, lending to Hitchcock’s tendency towards innovative filmmaking practices.

“All through the film we can hear sounds and voices from these apartments in the distance, carefully balanced to sound realistic and - as would be the case in real life - none too clear: however essential lines of dialogue from these characters are always intelligible. It’s a sophisticated and very clever piece of sound mixing: it would be another twenty years before this sort of concept became more widespread.” - Roger Wilmut

Hitchcock played with the extension of sound space in Rear Window to build suspense and establish atmosphere. When he wanted the audience to hear the city, it’s what we hear. When he wanted to focus on a single sound, he does.

This tactic shows the depth of the world around Jeff. It contributes to the isolation and complexity of his situation, as well as the neighbors around him.

“The muffled sounds of the neighbors’ suffering - the Thorwalds’ fights, Miss Lonelyhearts’s tears - are often conjoined to the sounds of nearby celebrations or to the quotidian sounds of children playing or a drain pipe leaking. Rear Window’s soundtrack represents an interplay of the tragic and the mundane.” - Hitchcock’s Rear Window: The Well Made Film by John Fawell

“Hitchcock varies extension in Rear Window. Sometimes he let us hear the big city thrumming outside the apartment. At other times he eliminates the larger cityscape entirely. At the very end of the film, the extension becomes extremely narrow, focusing on a single point, like a lone spotlight pursuing a character on a stage - the footsteps of a killer in the stairway, which Stewart can hear approaching.” - FilmSound.org