There are a few key steps any good composer will follow when it comes to jump scares. Here’s what you should look out for...

By Sophia Beams

If you’re watching a horror movie with a lot of jump scares, you might notice how certain films build tension before the scares. Sometimes the background music will stop, leaving dead silence where there should be a little bit of noise. Occasionally, it will build to a crescendo just before the scares happen, leaving you anticipating what’s coming next. It could be a low thrumming noise or a high-pitched beeping in the background that has you on edge. Each movie brings something new to the auditory world of jump scares, and it might seem like there’s no one way to create a good one. However, there are a few steps that any composer will follow when creating the best jump scare build-ups, and the more you watch out for them, the easier it will be to spot which movies follow which guidelines.

Repetitive noises

If you’re a big fan of the Friday the 13th franchise, chances are you’re already aware of this phenomenon. The tactic it brought to audience attention was the idea of creating a distinct, repetitive background noise that would play anytime jump scares were about to happen. In Friday the 13th’s case, it was a very soft, “ch ch ch, ah ah ah” that would appear – just barely – in the background music before the killer, Jason, appeared. The idea was that, over the course of the film, the audience would unconsciously begin to associate that noise with Jason; this way, any time the noise was played, they would feel nervous and on-edge without understanding why. This tactic has become much more common in recent blockbusters; you can look for a series of two to four notes that are played repetitively at high-tension moments in the film, a quiet background noise that continues until the jump scares occur, or even a particular instrument that is introduced right before something big happens (like a drum sequence, eerie piano, or even high-register harp or triangle chimes).

19 Hz (or lower)

This phenomenon is much trickier to spot – because you won’t actually be able to hear it. 19 Hz is the frequency at which the human ear can no longer hear sound. Instead, we register it as a very low thrumming noise, almost like muffled helicopter blades. It’s practically undetectable when mixed with background instrumentals, but the purpose it serves is key to creating a good horror movie. Even though we can’t technically hear it, any frequency played at 19 Hz or lower affects humans by making them scared, nervous, and uncomfortable. The frequency can even cause dizziness and panic attacks. Strangely enough, tigers roar at a frequency of 18 Hz; the roar of a tiger has been known to cause extreme fear and even temporary paralysis in humans, providing evidence to just how terrifying this noise can be. 19 Hz is the perfect frequency to make audiences feel major discomfort (ideal for setting up jump scares) for a reason they will literally be unable to detect, and many horror movies exploit this by introducing the 19 Hz frequency to their films during a particularly tense moment, or even by keeping it playing consistently at a low volume throughout the movie.

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Unexpected background noise

This is the key to creating legitimate jump scares. Audio cues can sometimes be cheap; they make the buildup to the scares too long, they resolve immediately after the jump scares, and they might even try to build tension but accidentally end up telling us exactly what’s coming and when. A well-executed jump scare won’t do any of these things, because it won’t resort to any well-known movie tropes: it should instead be entirely unexpected.

So how, then, can we predict the unexpected? It is tricky. But, the main idea is this: a good composer won’t allow jump scares to come completely unexpectedly. They have to have something; an unseen way of building the tension or a hidden clue in the background music that makes the audience a little bit nervous for a reason they can’t explain. Again, 19 Hz will do this, but it won’t be completely effective on its own. You can’t put a little bit of 19 Hz over Walking on Sunshine and expect audiences to feel fear.

A fairly clean example of these types of jump scares is from the most recent version of Nightmare on Elm Street (2010). This movie doesn’t shy away from jump scares, but it also doesn’t overuse them. And – with spoilers ahead for anyone who hasn’t seen this classic – the ending is a fantastic example of how to effectively create an unexpected jump scare. One of two surviving protagonists, Nancy, comes back home with her mother after having defeated Freddy Kruger. It’s over, everyone is safe, and the audience expects the traditional happy ending we see in horror movies; a short family recovery, perhaps with an epilogue of sorts. Not a fairy-tale ending, but still interesting enough to see a few survivors alive and well.

However, there is something important that occurs at the end of the film; a lack of background music.

This doesn’t appear to be a purposefully malevolent choice at first. It’s not sudden, and it’s not at a tense moment. The audio is instead focused on the character dialogue. There’s not a very strong sense of discomfort just yet; Nancy and her mother walk through the door and start talking about the events of the film.

There are two things we can use to recognize what’s coming. First, the silence in between the dialogue. Jump scares don’t happen when characters are talking. Jump scares occur in a moment of silence, because the audience has to be caught off guard, but if they’re caught too off guard, then there’s no time for them to process the jump scare before it’s already over – then they don’t really feel much of anything and the jump scare is unsuccessful. So, when Nancy and her mother are speaking to one another, there are long silences in between their sentences. Nancy says something, then it’s quiet while the camera changes angles and her mother takes off her shoes, then her mother says something, and it’s quiet while the camera changes again, etc. This happens for around ten seconds. It’s just enough time for us to adjust to this new auditory environment (Maybe this is how they’ve been speaking the whole movie? or, This is just a quiet moment, so there’s nothing to worry about.)

The second clue for the jump scares is something much smaller: Nancy’s mother sets her keys down on the table, and they are very loud. Why is this such an important clue? Plenty of objects make noise in movies; if the keys were silent, it wouldn’t be realistic. While this is true, it’s actually the volume of the keys being placed on the table that’s the issue. They’re suspiciously loud, almost as loud as the characters speaking to each other. This is an audio cue that intentionally draws our attention towards something: the silence. Even though the background has been silent before this moment, it’s the first time that we’re intentionally made to notice it: something is very, very wrong, and the keys draw our attention to that. The keys shouldn’t be that loud. Why are they so loud? Because everything else is dead silent. Why is everything else silent? Because something is coming… because jump scares are coming…

As promised, Freddy Kruger appears in a conveniently placed mirror behind Nancy’s mother just one second after she places her keys down on the table, and he kills her instantly. We are rewarded with our final audio cue that occurs almost exactly when Freddy appears in the mirror: a quietly catastrophic droning sound effect (not quite 19 Hz, though!) as he breaks the mirror and drags Nancy’s mother through.