Studies have shown that certain fearful music activates the brain’s alarm-response system. So what is it that makes some music sound scary? Psychoacoustics researchers have found that some auditory features that are common in horror music are inherently frightening. The most obvious way music can scare us is by literally imitating screams, like Psycho does. Here, the instruments mimic a quality of human screams called roughness. When we scream, we press a high volume of air through our vocal cords, causing them to vibrate chaotically. This creates a sound wave with an amplitude that fluctuates rapidly, which our ears and brains perceive as rough or harsh.