Let’s face it; if not for the sounds of saws cutting bones, crows cawing, or doors creaking, horror movies wouldn’t freak us out as much as they do.

But thanks to brilliant screen composers who have an arsenal of tools, techniques, and tricks at their disposal, these savage soundscapes can make us either shudder in our seats, or jump right out of them.

Toronto’s Mark Korven, who’s been scoring for horror films since the late ‘90s, has developed a way to create those responses without relying on studio technology. Along with Toronto luthier Tony Duggan-Smith, he’s created The Apprehension Engine, a Canadian invention that crashed into our consciousness two years back when a video of Korven playing it and explaining what it does was posted on YouTube.

It has since racked up more than seven million views, and Korven says Duggan-Smith “has received a stream of requests to build it, including some from a few fairly big names I’m not at liberty to discuss.” He says the unique instrument, which famed musician Brian Eno has called “the most terrifying musical instrument of all time,” costs $10,000 (USD), and about 10 have been bought so far.

“The idea was to create something that would enable me to create horror soundscapes,” Korven says. “I wanted to get away from sampling and using sound effects, and I wanted something that was acoustic. But once I got it, I couldn’t resist plugging it in and using pedals to get more effects,” he says, chuckling.

Korven says after conceptualizing The Apprehension Engine, he drew up a diagram and asked Duggan-Smith to build it in two weeks. “I told him I wanted a spring reverb, a hurdy gurdy, and an e-bow [the hand-held electronic bow for guitar], since I love using it. He loved the idea. He was, like, ‘This will give me a break from the endless stream of building guitars.’”

Korven says he never scares himself with the sinister sounds the “steampunk”-looking instrument produces. “I’ve been scoring a lot of horror films, and it’s become a relaxing thing, a cathartic thing,” he says. “It’s like having some internal tension, and you can express it in a musical way and expel it.”

“I want to be outrageous in the sounds I come up with.”

Korven has a response for purists who might question whether The Apprehension Engine is an instrument or not, and even if it makes actual “music.” “My definition of music is sound that has some kind of emotional impact,” he says. “On the other hand, something that is unbelievably bland like muzak, I don’t consider that music.”

Korven concedes that The Apprehension Engine is not an instrument in the traditional sense, since “it’s hard to do anything melodic or harmonic in a conventional way [on it],” but adds that “its restrictions make it creatively freeing. It’s like a foley box, it’s not a cohesive whole, and the possibilities are endless.”

Korven says that when he’s commissioned to make a soundtrack for a horror film, he “just experiments. When I sit down with it [The Apprehension Engine], I’m not thinking notes and harmonies. I’m thinking, ‘How can I hold the e-bow in a different way,’ or, ‘How can I touch something to create a sound I’ve never created before?’”

Korven describes his sound as “my brand of sonic lunacy, that’s funky and dirty.” He says that as a screen composer, “you can spend your entire career doing what directors ask of you, but I have all the freedom in the world to do what I want to do. And what I want to do is to be free sonically, and outrageous in the sounds I come up with.”