Did you ever really pay attention to the sounds in a movie?  I don't mean the overall quality, or the actors lines.  All the other sounds and noises .. the birds, the creaks, a horses footstep.  Those things!  Here's a neat look at how all that gets in the mix!

When a Hollywood movie is shot, the microphones are only focused on picking up the dialogue. This means most of the background noise is lost, and it is up to an artist called a "Foley artist" to go back and recreate this background noise in post-production.

In this clip, Foley artist Gary Hecker, who got his start working on "The Empire Strikes Back," demonstrates the unexpected techniques a Foley artist will use to make movies sound right.