The science behind why Black Sabbath and Ozzy Osbourne’s music sounded ‘satanic’
The tritone has been blamed for chaos, banned by choirs, and embraced by metalheads. Here’s what the ‘devil’s interval’ really does to your brain.
By Simon Ingram
The idea that two simple notes—not a song, just tones—could be “banned“ may seem ludicrous. But that’s the legend behind the crushing opening riff of Black Sabbath’s 1970 debut. With just three ominous notes, guitarist Tony Iommi, alongside the anguished vocals of the late Ozzy Osbourne, unleashed a sound so unsettling it was said to have been forbidden for centuries.“Those notes were banned many years ago,” Iommi told the BBC in 2014. “It’s supposed to have been a satanic thing.”
While rock legend has never been the most reliable (see: Ozzy and the bat), this one does have a whisper of truth. Black Sabbath recruited what music theorists refer to as the ‘tritone,’ —a dissonant interval once avoided by medieval choirs and now known in music lore as the “devil’s interval.” Also referred to as the augmented fourth, diminished fifth, or sharp eleven, the tritone spans three whole tones on a scale, creating a clashing, unstable sound that has long made listeners squirm. But what is it about this ancient musical interval that has unnerved audiences for centuries—and why does it still strike such a primal chord?