Sound: Codes and Conventions

So far I have observed:

• There is often an audio bridge between the last ident and the opening shot, particularly in comedies.
• There is also often some kind of non-diegetic music within the opening scene.
• The sound is often designed to make the audience think and feel a certain way, in  horror this is done by making low notes beat faster and high notes be drawn out.
• This is easily tested by doing a commutation test and swapping out the instruments with another, unlinked instrument.
• A key point that I have noticed is that the music in non-invasive, meaning that the audience shouldn't notice it. This rings true even for the horror  movie Childs Play IV(Yu, 1998), where the music fades out for the kills, something which the audience may not consciously clock immediately, but invokes a reaction all the same.