The film Clown Train illustrates the importance of sound in film production, specifically for its distinctive genre.
The use of diegetic sound works to establish the atmosphere of the train’s isolation from the outside world, as well as to fill in the emptiness brought about by minimalist dialogue in the beginning and the end of the film. Loud ‘white’ noise and random thumps contribute to the anticipation of the genre’s climax, as usually taken advantaged of by many films of the same style. Other aspects of sound, such as the electric whizzing, work to compliment its visual forms, in this case, the failing lights.
Other genres also utilise sound in constitution of the environment. This is strongest in films set in a war, when characters are found indoors and are not necessarily in view of the ongoing violence. The repetitive use of gunfire and artillery noises, despite being somewhat muted, assure the audience that the characters remain in the same locale, and have not been teleported to a flashback of sorts.