Media Language- Sound

Sound is one of the main aspects of  horror films as the different tones and tempo's help to determine different situations. The sound used will help to evoke emotion within the audience. Isolated instruments are often used before a key event which helps link the idea of vulnerability to the audience and to also help in building tension.

Long suspenseful notes often help contrast with short sharp notes to help shock the audience, or in other words, help show a change in the general mood. Also, the use of extreme but intentional changes of pitch or tones can often be affective. For example, low long brass notes which may suddenly occurs may help magnify the situation such as a high, fast paced sound representing the fast paced action, or to make the audience feel immediately tense.

Diegetic sound is any sound that the character or characters on screen can hear. So for example the sound of one character talking to another would be diegetic or the sound of the wind or bird song. Non-diegetic sound is any sound that the audience can hear but the characters on screen cannot. Any appearance of background music is a prime example of non-diegetic sound. 

Within the zombie horror genre sound is very important, sound is used like in most other films to build tension and excite the audience. Sound is going to be especially important within are film due to the that fact that the main villains of the film, the zombies will not actually be shown to the audience, so there existence shall be shown through dialog and sound effects and general music.

An example where music and sound was used effectively to convey danger without showing the initial threat was Jaws. Jaws (1975) is a film directed by Stephen Spielberg and is about a gigantic great white shark who begins to menace the small island community of Amity, a police chief, a marine scientist and grizzled fisherman set out to stop it.

http://www.imdb.com/title/tt0073195/

 

Programs such as The Walking Dead are also very effective in there use of non-diegetic sound. 
Within this program you can not always see the zombies that surround there current hide out but the audience know that they are there because of the ever present noise of there groaning. This teamed with the noise of the surrounding woodland and streams makes the situation appear more believable.