There’s few human beings that would fail to recognize a scream of terror. But what makes that type of scream so universally recognizable? Up until recently, scientists studying human-produced noises have usually relied on a few conventional ways of visualizing the sounds. These included graphing the pressure of sound waves and/or plotting their frequencies over time. These study modalities when applied to human screams of terror, however, only revealed that these screams were louder and of higher pitch than normal speech. And, as David Poeppel of New York University put it, lots of things are loud and high-pitched. Using a modulation power spectrum that charts how quickly the volume of a sound changes over tiny amounts of time, Poeppel and colleagues decided to take another look at fearful screams, the type that make your hair stand on end. More tomorrow.