Horror films rely on all sorts of tricks to induce their frights: jump scares, atmosphere, and creepy or gory visuals. They also rely on something else that’s often overlooked: sound.

Sound, including music, can play a key role in how scary something is. Consider, for example, Robert Wise’s 1963 The Haunting; one of the most terrifying moments in that film is the scene in which the girls huddle in their room as an infernal banging roams the hall. We never see the ghost; we simply hear it—and if one turned down the volume and watched that scene without any noise, it would just look like two women making goofy faces in a room.

That said, here are ten films that rely so heavily on sound or dialogue to make them frightening that watching them without the soundtrack—or with an alternate one—would completely change the experience.

The Haunting (1963)

This film relies on its score, Nell’s internal thoughts, and the noises of the mansion so much that to turn off the sound renders it a plain drama focusing on the consumption of meals, the drinking of cocktails, and the unpacking of suitcases.

In The Haunting, Claire Bloom, left, and Julie Harris have drinks in their hands on several occasions.

The Blair Witch Project (1999)

Since we never physically see much except for a few hand prints pushing on the tent in the middle of the night, this film, sans-sound, looks like somebody’s bad home movie of teenagers arguing in the woods.

Lovely Molly (2011)

Most of Lovely Molly’s creep factor comes from the sounds of the house and the “demon” or whatever’s stalking her, as well as from the dialogue that Molly has with the other characters. Because it lacks even one terrifying image, without sound, it just looks like the study of a blonde chick hanging out in a dilapidated farmhouse, doing drugs and drinking wine.

Lovely Molly spends a lot of time drinking, smoking, and shooting up. When we can hear the film’s soundtrack, there’s a point to all of it; when we can’t, the film reads like daily diary of a druggie.

Frogs (1972)

A sans-sound showing of Frogs looks like a soap opera set in the Deep South.

The Amityville Horror (1979)

Without sound and the tense scoring, the opening sequence of the DeFeo murders looks like anything seen on a cop show, and the film that follows is a dull rendering of a family going about their daily activities.

Hollow (2011)

This found footage slow-burn features two couples on vacation in a village haunted by a terrible legend. Sound-free, it’s reminiscent of an angst-filled young adult drama.

The Witch (2015)

Soundless, this is a docudrama about the puritans.

The Innocents (1961)

Most of the scaring is done with disembodied voices, so without sound, some scenes could almost be considered one of the black-and-white episodes of Upstairs, Downstairs.

Apollo 18 (2011)

Since there’s really no “creatures” to speak of—and what “creatures” we do see look like rocks—a soundless watch reveals an out-of-sequence pile of random footage from a NASA mission to the moon.

The Visit (2015)

It’s the antagonists’ odd behavior and speech that make this film scary, so if we don’t hear anyone talk, it looks like a child’s crude video chronicling of a week with the grandparents.