IRLD-sound 
Many sounds of moving images are IRLD (In Real Life Different). A typically IRLD-sound is a moving fists in a brawl. The big awful sound that accompainies the villain, when he is slowly moving a fingertip on the heroine's legs is unrealistic. Some sound emitters (on screen) are in real life silent. 

 
Conventions of sound = Reality 
The heavy use of IRLD-sound have altered our perception of reality.  

A veteran of World War II gave this startling account of his first day in combat : 
- Believe it or not, the first thing I thought about was how it did not sound like war. Having grown up watching Hollywood war movies, I expected a lot more sounds and much bigger sounds, it was not until I was hit I realized what I was in was real.[1] 

Autenticity  =  Audience expectation 
The autenticity of sound effects is today not the on-location-recorded sound but in the listener's expectation of how something should sound. If a sound is too jarring to conventional concepts the film maker is inviting audience disbelief not only in that particular sound, but in other production values as well.  [to Added Value]  

Rich Altman use the term Sound hermenuetic - when a spectator/auditor tries to visually identify the source of the sound. 

1. Page 77 "Tampering with reality" in Robert L Mott: Sound effects, Radio, TV, and Film 
 
 
 

FilmSound.org    www.filmsound.org       Oxford University: "...an excellent collection of resources and links.."