Horror movies have the unique ability to cause nightmares even to its biggest fans. And it’s not so much the supernatural entity lurking in the shadows nor the monster hiding in the closet waiting in earnest to makes its debut that causes the biggest screams and the heightened moments of terror, but the classic sound bites. It may be surprising to know that the majority of the hair-raising sounds are made by a delicate instrument called a waterphone or ocean harp. The instrument has been the choice for several horror classics including *Poltergeist*, *Let The Right One In* and *Aliens*. Designed by American artist Richard Waters, the waterphone looks like a cylindrical harp varying in height played with a rod or bow. Made of stainless steel, the harp can even be played underwater. In fact, it has been used to communicate with orcas. Take a look at this video and be warned, the eerie sounds played in the dark may cause sleepless nights.