Noir sound

The use of sound in film noir was wide spread as film was still in it's early years and of course with out the tech we have today they had to rely on more primitive methods of building tension and suspense. The easiest and most effective way of doing this was to use sound. 

One of the most famous uses of sound in early film to denote action without having to show it is the sound motif that accompanied a stabbing motion in Psycho. 

In the intro to a lot of the film noir that i've been researching it seems to be an almost universal theme to have classical sweeping orchestral music to accompanying the opening shots this can be seen in my opening shot analysis of Brutal Force and Turning point which both follow this theme. 

In scenes in which our hero, usually a private investigator or deceptive, is sneaking around mounting violins are used to build tension. This method has gone on to become almost a cliche in horror films. 

When our hero is investigating someone or something it is normally accompanied by a sound track of slow smooth or bluesy jazz giving it a surreal feel and everything feeling slightly off and strange. 

There is also a common use of voice overs and non-diegtic sound to allow us to hear the thoughts of the character without the actor having to do overly obvious actions to give us insight into his thoughts. Today this method has become out dated and we tend to leave the characters thoughts ambiguous to let the audience decide.