The sound design trick horror movies use that has nothing to do with jump scares

The scariest sustained dread in horror films rarely comes from jump scares — it comes from a sound design trick called infrasound, frequencies below normal human hearing that the body still registers as unease without the audience consciously hearing anything unusual.

Several acclaimed horror scores deliberately layer these frequencies under quiet scenes specifically to make audiences uncomfortable before anything visible happens on screen. Test audiences report feeling on edge during scenes with no visual threat at all, purely because of a frequency they can't consciously identify.

Once you know to listen for it, you can sometimes feel the moment a scene shifts from calm to dread several seconds before anything visually changes. The dread was always in the sound design, not the images.

Part of the deeper dive: The Guide to Watching Movies and TV More Critically (Without Ruining the Fun).