Critical theory: Sound - Understanding how to use it

My initial thoughts on using sound in film:

• Background music can create a mood, it helps you understand more about what is going on and how you should feel.
• Sound motif's help the audience to understand what sort of character the film is dealing with.
• The sound establishes moods and might even lead the whole atmosphere of a film, driving its narrative.
• Can represent something
• Signifys things which are going to happen
• Give you an idea of the genre

Having analysed Waking the dead - these are my next thoughts: