Production sound:
On the set the location recordist tries to record dialog as cleanly and crisply as possible, with little background noise.

Post Production sound
Dialog editing is mostly a matter of cleaning up production sound. Dialog can be edited to affect characterization. Suppose the director wants to make an arch-villain more domineering. A mixer could raise the volume of his voice and adjust the tonal qualities to make him sound larger than life.

Dialog can also be edited to affect characterization. Suppose the director wants to make an arch-villain more domineering. A mixer could raise the volume of his voice and adjust the tonal qualities to make him sound larger than life.

Sound effects tracks are normally built from scratch. We would not want to hear everything that really could be heard in a given space.  Sound is very subjective and dependent upon the visual context and the mood set up in the image. The soundtrack of real life is too dense for film. In the real world, our minds select certain noises and filter out others. We mentally foreground the person speaking to us even if the background is louder. On film, the sound effects editors and re-recording mixers have to focus for us.

Click here to read about how sound is designed and produced for a major Hollywood feature.
 
 

In Films
-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'--.

- sounds sometimes are made of  humans screaming in pain!!
-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'--.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'--.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'--.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'´¨`'-.,.-'

The ambience  in Lecter's dungeon has been made from a human screaming in pain.  The scream is
 processed, slowed down, and played in reverse. It's a low tone that rises and then comes down again. Whenever Agent Starling is down with Lecter you hear this sound.

Click here to read about the creation of sound effects in scenes from Jonathan Demme's Silence of the Lambs and Philadelphia.  

 TITANIC - Sound Design For James Cameron's Epic Ocean Saga
 
 

From the Newton's Apple series, this is a neat explanation of the secrets behind movie sound effects and Foley.