Most of us probably never notice the sound effects foley artists create for movies. They’re usually ambient sounds like footsteps, swishing cloth, or doors opening and closing, intended to fade into the background rather than grab our attention. But there’s one genre where foley effects frequently jump out at us: horror movies.

Sounds like gurgling blood, breaking bones, or creaking furniture are designed to be noticeable, and to freak us out. But, of course, foley artists can’t actually record real ghosts and ghouls—so over the years, they’ve come up with some pretty creative ways to make the sounds that spook us.

In order to figure out exactly what goes into making scary movie sound effects, The Credits interviewed veteran foley artist Gary Hecker, who has worked on everything from the most recent reboots of The Thing (2011) and A Nightmare on Elm Street (2010) to The Empire Strikes Back (1980) and the original Friday the 13th (1980).

He told The Credits that some of the most effective tricks for making spooky sound effects are actually pretty simple. For instance, in order to create the sound of gurgling blood, he just puts water in his mouth and sprays it out. “Using my audio gear, I can adjust the pitch of the sound to make it sound thick, like blood. There are lots of different blood noises, and I can make them really specific—bubbling, squirting, oozing—depending on the scene,” he explained.

The sounds of creaking stairs or floorboards, meanwhile, are created using what Hecker describes as a “really cool, creaky chair.”

Vegetables also make great sound effect props, according to Hecker. He explains that in order to mimic the sounds of stabbing, he simply stabs different cabbages with a knife to create a crunching sound.

The sound of breaking bones, meanwhile, requires little more than a piece of celery. Hecker says, “I take a big stalk of celery, wrap a chamois around it, and crack it in half. So that’s the sound of bone breaking under skin. Then for the gooey stuff, I layer in a wet chamois and my voice, so it sounds like bones cracking and blood spraying.”

In his interview with The Credits, Hecker reveals the secrets behind ten different spooky sound effects. Check out the full list here. And the next time you find yourself getting freaked out by a scary movie, remember those creepy sounds aren’t real—and they might be little more than a few salad ingredients.

[h/t: The Credits]