Why do we love movie soundtracks?

In 2009, a study by Goldsmith’s University found that different moods of music directly affect how people perceive emotion. The findings of “Crossmodal transfer of emotion by music”, published in Neuroscience Letters, were that people perceived a happy face to be happier if they heard just 15 seconds of happy music before seeing it (and similarly a sad face to be sadder if they heard 15 seconds of sad music), and that neutral faces appeared either happy or sad depending on whether the music played was happy or sad respectively.

It was a landmark moment that connected music with visual emotional cues more empirically than ever before and one that confirmed just how intrinsically music and emotion are linked to one another in the human brain.

It is no surprise, then, that what often contributes to the greatness of a film is a well-planned or cleverly-composed soundtrack. Music can be used to elevate the emotional weight of the action we see on screen the same as it elevated the emotions of the faces it accompanied in the aforementioned Goldsmith’s study.

Indeed, films like Pulp Fiction (1994) and Easy Rider (1970) are inseparable from their brilliantly crafted soundtracks and it’s undeniable that fewer tears would have been shed over films like E.T. and Gladiator had John Williams and Hans Zimmer not written such moving scores for them. Would The Good, the Bad and the Ugly (1967) ever been as famous without Ennio Morricone’s genre-defining theme music? And can you imagine Alfred Hitchcock’s Psycho (1960) shower scene without those high string stabs? There’s little doubt the scene wouldn’t have become so famous, and remained in so many people’s consciousness, without the iconic music that accompanies it.

How music sets the mood, creates suspense and elicits other emotional responses comes down to the fact that hearing is one of our five senses, and an essential part of our species’ survival according to basic evolutionary principles. Composer Neil Brand summed this up well back in 2013 when he presented BBC Four’s film music series, Sound of Cinema: The Music That Made The Movies. “Human beings are very good at interpreting sound. Right back to when our prehistoric selves will have heard a twig snap in a forest and thought, that's it, I'm dead”, he explains.

The ability of sound to induce a fight and flight response like this is closely related to the ability of music to induce a strong emotional response. "We have a very deep understanding of what music is doing, and it's very physical," says Brand. "We can feel it going into our ears via sound waves and it can produce all sorts of physical responses, including in the right circumstances an actual thud to the stomach.” The high string stabs in Hitchcock’s famous shower scene are reminiscent of animals’ cries of distress and it’s not a longbow to draw to suggest that that’s why the music contributes to a heightened sense of fear when experienced with the violent visuals on the screen.

It follows that dissonant, syncopated music is comparable to sounds of distress in nature and so makes an affective horror soundtrack, and that music that seems to “build” and “climb” through soaring melodies will make us feel elated once it reaches its highest point and the tension is released in ecstatic sound. Music like this mirrors the ups and downs, and soaring of emotions felt during love, for example, and perhaps that’s why it affects us in the way that it does.

The same year as Goldsmith’s released their study on the transfer of emotion by music, researchers from McGill University tested the pleasure-related chemical dopamine in relation to music for the first time, and found that dopamine levels increased by nine per cent when people were listening to music they claimed to enjoy. The study, published in Nature Neuroscience, may not have got to the crux of why music is so important to humans, but certainly proves that it is important nonetheless. With the importance it holds, and the power it has to set mood, it’s no wonder filmmakers utilised music to bring pictures to life even before technology allowed sounds to be synchronised with the moving pictures on screen.

From the 1890s onwards live musicians, from solo pianists to full orchestras, improvised or played pre-composed music along with silent flicks to add emotion and help drive the action. Scores made for this purpose descended directly from the legacies of composers like Beethoven and especially Wagner, whose use of leitmotif—that is, different recurring melodies for different characters in operas such as Der Ring des Nibelungen and Tristan und Isolde—remains the driving principle of film music today. John Williams’s score for Star Wars (1977) includes memorable and specific themes for Princess Leia, Yoda and Darth Vader, for example.

Film music was revolutionised in the late 1920s when sound was captured on celluloid film and heard in synchronisation with the images on the screen. The Jazz Singer (1927) was the first major feature to incorporate music as well as synchronised voices, heralding the arrival of “the talkies”. After that, composing or selecting music that followed and elevated the story on screen became an increasingly important part of making a film. Film composers since have had the power to create memorable and beloved melodies that people would associate with the myriad worlds films allowed them to escape to.

Directors like Stanley Kubrick, Jean-Luc Godard and Lars Von Trier are well known for treating music as an integral part of the plot, often constructing scenes around pre-existing pieces (instead of the other way round) and selecting music before deciding on the sequence of action. The atmospheric opening of Kubrick’s 2001: A Space Odyssey (1968), built around Richard Strauss’s Also Sprach Zarathustra, offers a good example of this.

As does Godard’s collaging of image and music in Pierre Le Fou (1965) where the music is cut as abruptly as visual scenes to contribute to the surrealism. And Lars Von Trier’s reliance on the suspense and resolution of the prelude from Wagner’s Tristan Und Isolde to make up the entire soundtrack for his 2011 film Melancholia is another striking example of a director taking inspiration from musical structure to dictate the structure and emotion of their film.

And sound editors and composers continue to innovate. Thom Yorke’s soundtrack for Suspiria (2018) uses electronics, dissonance and syncopation to reflect and amplify the film’s sinister and macabre atmosphere, and is as memorable as the disturbing scenes the film faces us with. In fact, it’s hard to imagine the film without Yorke’s music, which was even used in the pre-release trailer to pull us into director Luca Guadagnino’s irresistibly dark world.

Mica Levi’s stark score for Pablo Larraín’s 2016 Jackie really captures the feelings of unreal suspension and shock that come with sudden loss and grief like that felt by Jackie Kennedy in the days after her husband John F Kennedy’s assassination. In terms of compiled soundtracks of existing popular music, Baby Driver (2017) is a recent masterclass in how music can be as integral to the plot as it is to driving the action on screen.