FOLEY

FOLEY is the technique of augmenting or replacing sounds and noises to enhance the visual illusion.  For example, in all of the “Dirty Harry” movies, Clint Eastwood’s gun fires with a stronger sound than the villain’s gun (even if it is the same).

Foley work used to be done exclusively in a studio that contained many devices for creating sound effects (such as various small creaky doors, boxes of broken glass to be dropped, etc).  These days many people use a library of sound effects instead.