When it is hard to get good quality sound and video in the same scene for example when a take was done excellent and the video is on point but the sound isn’t.
An incidental sound is stuff doors creaking doors slamming footsteps
An exaggerated sound is a sound that is inflated to sound worse than it really is. An example of this is in old time fighting films like Rocky the punches used in the film are exaggerated.
Voice-overs are pre-recorded scenes of voices and sounds and then used to put in over the recorded scenes. Most films are over dubbed with sound they re record sound in a stupid for better quality
Natural sounds are sounds that are not recreated but are actual noises from the atmosphere, like wind blowing
Sound design are sounds used to create a certain emotion and reflect Sound design is the process of specifying, acquiring, manipulating or generating audio elements. It is employed in a variety of disciplines including filmmaking, television production, theatre, sound recording and reproduction, live performance, sound art, post-production, and video game software development. Sound design most commonly involves the manipulation of previously composed or recorded audio, such as sound effects and dialogue. In some instances it may also involve the composition or manipulation of audio to create a desired effect or mood. A sound designer is one who practices the art of sound design.
Voice Overs: http://www.youtube.com/watch?v=QZO0P3XhpZo
Natural Sounds: http://www.youtube.com/watch?v=b2njHW9ydWs
Not every film or game has to have a sound track on it because they could be trying to create a certain effect.