There are a great number of things that can go wrong while making a horror film, but nothing is quite as bad as making one that isn't scary. In a previous post, we talked about some basic and general concepts, like achieving atmosphere and suspense, to keep in mind while you put your scary movie together, but Movies.com has shared an episode from PBS Digital Studio’s It’s Okay to Be Smart series that sheds some light onto one aspect of horror that may be the key to unlocking the horror potential of your film: sound.

I'm sure we can all think of films with music and sounds that scare us the most -- The Exorcist's "Tubular Bells" and Mercedes McCambridge's voice, the cawing from The Birds, or the screeching violins from Psycho. But, why are sounds scary? What turns vibrations into something our minds consider scary? Maybe that's the first question we need to ask ourselves before we start thinking about working on the sound design on our horror films.

The It's Okay to Be Smart episode explains that there are two ways that sounds can be scary: by being sudden, or by generating a "frightful" tone. And sound causes an interesting reaction in the brain in terms of fear that is quite different from the reaction the brain experiences from seeing something scary.

Not only that, but sound information actually travels faster than the information we receive from sight, which suggests that humans evolved to use sound (as opposed to sight) as a first defense against predators. So, essentially, it may be fair to say that sounds are scarier than images. The video below explains things in more detail below:

So, we find sounds from predators scary, like a growling dog or hissing snake, because we have to in order to keep ourselves alive. The roar of the T-Rex from Jurassic Park is still absolutely terrifying to me. But, what is it about those sounds that alert us to imminent danger? The episode above talks about "nonlinear sounds," which include rapid frequencies, nonstandard harmonies, and noise.

Some of these include sounds made by the theremin and trautonium (Composer Oskar Sala used the trautonium extensively, including in The Birds,) as well as what's known as the Shepard Tone, a sound consisting of a superposition of sine waves separated by octaves, which gives the illusion that the tone is getting increasingly lower or higher. Check out some examples below:

What do you think? Does this information give you any ideas on how to compose sound for your horror film? Let us know in the comments.

[via Movies.com & Filmmaker IQ]