What happens when a horror movie composer and a guitar maker join forces? They create the world’s most disturbing musical instrument. Affectionately known as "The Apprehension Engine," this one-of-a-kind instrument was commissioned by movie composer Mark Korven. Korven wanted to create spooky noises in a more acoustic and original way—but the right instrument didn't exist. So his friend, guitar maker Tony Duggan-Smith, went deep into his workshop and assembled what has to be the spookiest instrument on Earth.