From David Lewis -
When you watch a motion picture you are experiencing a story almost like you are right there in the action. One way of simulating the experience comes from big help of the audio that was put into the movie. The audio controls much of the mood in the movie and can either make or break the content being shown. Here is a small insight into how technical and how much creativity goes into creating audio for a big Hollywood motion picture.
Example: "'Inception' Sound for Film Profile," Vimeo