Non-linear sounds are typically harsh or unpredictable sounding and it is thought that animals (including humans) produce them when they are under threat in order to attract the attention of others – typically, the sounds are evocative and difficult to ignore. The researchers hypothesized that simulated non-linear sounds might therefore be used to manipulate the viewer’s emotions and make a film soundtrack more evocative.
In order to test this idea, they selected over 100 highly regarded war, action, drama and horror films. Specific genres were targeted so that the scientists could examine differences in the use of sounds between genres – if their hypothesis was correct, they would expect to find observable differences in the use of non-linear sounds in films which had different emotional content.
After performing detailed sound analysis on 30-second samples from “an iconographic scene that epitomized the film’s genre”, they discovered that not only did the clips make marked use of non-linear sounds, but films from different genres did indeed display measurable differences in the way they used the sounds.
There are a plethora of ways to produce nonlinear sounds artificially – from conventional orchestral techniques (including vibrato and trilling) through to electronic synthesis (such as the manipulated animal sounds heard in King Kong or the synthesised avian language used in The Birds). As such, filmmakers have a huge palette of nonlinear sounds available to them and this research suggests that they do indeed use these effects to manipulate the viewers’ emotions and increase the impact of their films.