Sound

It is quite easy to forget that the fear factor of almost any horror film would decrease dramatically (if not completely vanish) if the auditory features were removed or altered to something not befitting a horror film. This might sound a huge exaggeration, but it is most definitely not. All you have to do is turn down the volume on your TV during a dramatic scene in a horror film to realise the enormously important role that music and striking sound effects play in creating a complete and truly frightening horror film experience. If this important and amazing composed music is not in some of the key scenes of this film, then the mood will definitely sink to quite a flat atmospheric feeling for the audience. 

Sometimes in different horror films, music isn't really needed for the opening credits to create tension or atmosphere. In some horror film openings, they only use sound effects to set the mood of their film. For example, in the film se7en they don't really use a set peace of music for their opening, it is mainly electro sounds and weird beats in the background. This still ties in with the theme of the film and can create an atmosphere of tension. The clips also move in time with the music and have a jittery effect, almost showing the beat of the sound effects in the clip. 

On the other hand, music isn't always needed to create tension for the film that you are making or watching. In films like "The Woman in Black", music isn't rally used when scary scenes or scenarios occur in the film. Instead all you here is either the actors heavy breathing or the objects he is interacting with. For example if he  is walking on creaky floor boards then the only sound you will be able to here is the footsteps he is taking to get to the destination. In many ways this can create a more dramatic and tense build up to the climax of the scene because of how anxious the silence can make the audience.