Audio post production can be described in a number of loose terms. But most commonly, it refers to the different production stages between the primary actual studio recording and the final master recording. In between the two extremes, an audio post production involves-
I.    Sound design,
II.    Sound editing,
III.    Audio mixing,
IV.    Effect additions.
Sound design
This happens to be a technical yet highly creative field. The person who does the ‘sound design’ is called the Sound Designer. Sound designing has nothing to do with compositions. So it does not deal with any film, play or music recording. Neither does it work with any gaming software or multimedia project. Sound designing is all about manipulating audio parts to give them special and desired effect.
Sound Editing
At this stage, the sound editor creatively selects and assembles different sound recordings. This is done to prepare the audio for a final stage of sound mixing (also known as mastering). This way, sound editing is useful on TV programs as well as motion picture.
Sound editing is widely used in video games. It is also used in productions that deal with recorded sounds or synthetic sounds. In general sense, sound editing is done when there is any need to repair imperfect, un-dramatic, and or technically low quality sound recordings.
For decades, sound editing has been a part of filmmaking art. When it comes to motion pictures, sound editing help the visual goals in creating a desired impression. The Academy of Motion Picture Arts is one of renowned names in sound recording.
Audio mixing
This is a process that involved mixing up a number of sounds. The idea here is to combine these recorded sounds into a channel or multiple ones. Thus you see the 2-channel stereo is very popular form of sound mixing. Here is how the process goes.
A source for audio mixing will signal a number of things. Most common signaled things are the level and frequency content. In addition, the source will also signal dynamic and panoramic positions. These are usually manipulated using audio editing technology. But the editor also adds different effects like reverb or eco.