(creepy music) - Horror films don't get much respect.

But while horror has often been dismissed as lowbrow, its music has been in-cra-ba.

- Listen to the score from the 2018 horror thriller Bird Box.

(tense music) Now check this out.

("Polymorphia" by Krzysztof Penderecki) Hear the similarities?

This experimental composition was a key part of The Exorcist, a film that changed horror music forever.

But what is that sound and how did it come to influence the horror films of today?

- Nahre and I are gonna compose a score for an original scary short.

But first, let's take a look back at how scary music has evolved from the silent era to The Exorcist to today.

- Since there's been film, there's been horror.

In the silent era, most films would either have no music or they would be accompanied by live musicians who would play popular or classical tunes.

Only a handful of silent horror films were accompanied by original scores.

The music written for the 1920 release of The Cabinet of Dr. Caligari was described by one theater runner as "eligible for citizenship "in a nightmare country".

The first time a thematic musical score was written for a feature-length American talkie was for the 1933 monster movie King Kong.

Written by composer Max Steiner, this score utilized techniques that would go on to be used in horror films for decades, such as Mickey Mousing, in which music matches a character's action and leitmotifs which are short recurring musical ideas that typically signify the presence of a monster or a villain.

It's a technique John Williams would later use in what's likely one of the most memorable film scores of all time.

(Jaws theme plays) This two note leitmotif is perfect not only for its menacing simplicity but also for its functionality.

The quicker it gets, the closer we know the shark is.

(woman screams) - During Hollywood's golden age, horror films and the scores written for them often lacked subtlety.

The music usually told the audience what to fear.

- 50s was so big, giant ants and these aliens from outer space, where 60s, Psycho kicked it off.

It was personal.

It's a lot of interpersonal drama.

Bernard Herrmann's score in that is iconic.

(tense music) (she screams) - Psycho's shower scene is one of the earliest examples of the jump scare and is one of the most famous examples of a stinger chord, a common horror music technique where musicians sharply attack the chord to reinforce the moment of surprise.

(suspenseful music) Hitchcock originally wanted the shower scene to be silent, but composer Bernard Herrmann decided to write a piece featuring violins playing the shrieking upward glissando, which is produced when a violinist glides their fingers up or down the strings as they play.

Hitchcock later said that "33% of the effect of Psycho "was due to the music".

- I watch a lot of superhero movies.

Sure, the Avengers score is cool, but I'm not gonna think of the Avengers score when I'm kicking butt.

But when I'm scared alone at night, I think of that horror movie score.

- One reason the stinger chord has so effectively heightened terror in horror films is that they manipulate the deep-rooted fear centers in our brains.

- What makes something scary?

Experimental work has shown is that screams that are fear-based screams, they're known to have a very particular kind of acoustic signature.

It's called roughness.

And that gives it the kind of scraggly, fluttery vibe, whether they're vocalized sounds or alarm sounds or other sounds, it's the ones that have increased roughness feature, and that's what you interpret as a listener as fearful.

It could be a guitar string, it could be a piano sound.

It could be anything.

- Now let's fast forward to the film that changed horror music forever, The Exorcist.

William Friedkin's 1973 classic was so terrifying that it caused audience members to faint, vomit, and protest its release.

Some people even thought the film itself was possessed.

That's partly because of its unforgettable soundtrack, which included disturbing experimental compositions that went on to shape the way horror scores and soundtracks sound, even to this day.

("Polymorphia" by Krzysztof Penderecki) That's the sound of Krzysztof Penderecki, the leader of the Polish School of Avante-Garde Composers in the 1950s and 60s.

To get this haunting sound, Penderecki used tools like sound masses and tone clusters.

- Penderecki's score, I don't know, it sounds classic.

I love a song that I don't know when it was composed, I didn't know if Penderecki was from the 1700s or now and I love that it has this timeless sound to it.

It's timelessly scary, as well.

- So to create a tone cluster, you basically take a number of pitches that are a semi-tone apart.

For example, F sharp, G, G sharp.

(plays notes) These are all tone clusters.

With sound mass, the focus is more on the effect as a whole, where we have a clump of pitches (plays sound mass) where the specificity of each note and rhythm matters less than the texture as a whole.

His use of these compositional tools defy the classical form and help take The Exorcist to a demonic dimension.

- Although Penderecki's music feels like a horror film, he didn't write it for the screen.

Much of his experimental work was inspired by the real-life terrors of World War II.

As a boy in Poland, Penderecki witnessed the violence of Nazi's in his hometown of Debica.

Penderecki's music was also used in another landmark horror film, Stanley Kubrick's The Shining.

Horror music, horror film.

- I've never seen a real horror film from start to finish ever, ever.

- [LA] Is this not your cup of tea?

- When I was little, I used to get scared watching documentaries about ... You know those documentaries that talk about haunted houses or whatever?

- Yeah, but that stuff be real, though.

- Do you think that there's a stereotypical horror film sound?

- [LA] I think the shrieking violins.

- [Nahre] Stuff in the higher register like ... (high notes play) (he yells) - [LA] Yeah.

- Or even any dissonant interval.

Dissonance is a common aspect of horror film music.

One of the most effective ways to utilize it is through the tritone, musical interval composed of three adjacent whole-tones.

A major third.

(plays major third) Or a perfect fifth.

(plays perfect fifth) These are all consonant intervals where they sit quite comfortably in the ear.

Let's compare that to a tritone.

(plays tritone) There's more tension there.

It's a clashing, dissonant sound that has helped it earn the name The Devil's Interval in music.

And you can hear it in many horror films, like during the canoe scene in Friday the 13th, where composer Harry Manfredini repeats two tritones a half-step apart.

(tense music) - Another common technique is to put familiar or non-threatening music into a creepy context.

Often, it's little kids singing children's song.

(haunting music) Also, quoting religious music can help set the stage for films that traffic in the demonic.

Wendy Carlos and Rachel Elkind used this technique in the opening of The Shining, with a recomposition of Dies Irae, a 13th century Gregorian chant.

(sinister music) - Playing instruments in specific or extreme ways is another powerful tool in horror film music.

You'll often hear violins play sul ponticello, which means close to the bridge, combined with tremolo to produce eerie me-shrul sounds.

Sometimes, simple techniques can be just as effective at heightening dread in horror films, such as using a bassline to mimic the sound of a heartbeat, as John Carpenter did in The Thing.

The steady heartbeat gives us a clue that something menacing is constantly lurking nearby and it's coming for the characters.

(heartbeat music) Say that, just with strings, there's something about sustaining a high note.

Like, can you hear that?

That just builds tension the more you do it.

- True.

- Also really low things like ... - Yeah.

- And then you put a cluster.

- Do you want to approach the me riding the bike in the hallway in front of the twins?

I'll approach the door.

- Okay.

- Now here's a score that we made for a horror film starring Too-sant Morrison from our fellow PBS series, America From Scratch.

(eerie music) - Little pigs, little pigs, let me come in.

Not by the hair of my chinny-chin-chin.

And I'll huff, and I'll puff, and I'll blow your house in.

(ax thuds) (eerie music) - [Both] Hi.

Come and play with us.

Come and play with us.

- Monstrum is a new show from PBS Digital Studios about monsters, myth, and lore.

This show is written and hosted by Doctor Emily Zarka, who has a PhD in literature with a focus on monsters.

Basically, she's a doctor of monsters.

Head to the link in the description to check out the show and find out the origins of iconic monsters.