How Does Film Sound Work?

Here's a closeup look at a piece of 35mm film — the kind you'd find in the projection room at your neighborhood multiplex theater.
filmstrip1
 Remember that what we call "sound film" is photographed and projected at 24 frames per second (fps). What you're looking at here is three frames, or one-eighth of a second of animation.
Now let's take a closer look at the right-hand edge of the filmstrip.
filmstrip2

The big white holes are "sprocket holes," which the projector grips onto in order to pull the film along — and, more importantly, to stop it for the briefest fraction of a second so that the individual frames can register on the eye.

The two squiggly white lines at the left are the sound — two lines because it's been recorded in stereo.

But how does the soundtrack actually work?
filmstrip3
 For the Disney version of the story, click here. From the 1940 film FANTASIA, this clip is almost completely inaccurate — but it's fun to watch.
   
filmstrip4
 For a more accurate — and equally (or even more!) entertaining — explanation, see Max Fleischer's lovely 1929 cartoon, FINDING HIS VOICE, featuring Talkie, Mutie, and Dr. Western.
And if you really want to study film sound in depth, spend some time at filmsound.org,
a very detailed website that's well worth exploring.

 

Return to ARTH 334 Handouts.

Return to Teaching.

Return to Home