Sound Audio is key when editing, using added music and sound effects will help build suspense. Exaggerated diegetic sound will allow tension to be created in the film. Fast and loud non diegetic sound can add to making the audience jump or feel scared.
Examples: Psycho The music in the shower scene in Psycho is very effective. In th video below, the effect of sound can be seen. The non - diegetic music sets the tone of the scene more so, creating a suspense building feeling as the pitch and speed increases, keeping audiences on edge. Wheras without it, there is a lack of emotion communicated and audiences almost felt confused as to how they are meant to feel as there is a lack of suspense and tension build. Without the music, the impact and effect of a conventional thriller genre is not present.
The Shallows
Non-diegetic, base drone music is used at the beginning of the trailer. The base music creates an unwelcoming start to the trailer, possibly foreshadowing further danger. It is also slow to suggest the danger is not building yet, it is to come soon. Diegetic sound of a character in pain and fear is then heard 'help me, help me', a conventional sound / piece of dialogue heard in Thriller genre's as there is often a victim who needs help from the hero of the film. The music then builds up and increases in speed to establish the danger and also symbol the panic of the main character as the shark attack is prominent. This puts the audience on edge as they know something terrible is about to happen, but also grips the audience to continue watching to find out. Therefore music is used to build tension, as conventional in the thriller genre, and also attract audiences's interest into the film, also conventional.