What do Black Sabbath and Jimi Hendrix have in common with West Side Story?
Diabolus in Musica: They all use the musical interval known as the tritone, otherwise known as “The Devil’s Interval.”
In the 12th century, Gregorian monks started creating what we now take for granted as Western music theory. If it weren’t for these guys, there would be no Limp Bizkit, no Justin Bieber, no Coldplay, and no Super Bowl half-time shows from the Black-Eyed Peas. So say thanks, I guess.
Back in the day, religious chants were sung in unison, or without any kind of harmonic interval. The first two used in common practice were the perfect fifth followed by the perfect fourth.
I won’t bore you with any more music theory, but the tritone derives its name from the fact that it is constructed from a root and a note that is three whole steps up.
This puts it between the perfect fifth and the perfect fourth, making it a diminished fifth or an augmented fourth (which are the same thing).
Pretty scary, right?
The fourth and fifth were accepted for use because they are considered to be the most consonant intervals, aside from a full octave. They were deemed acceptable in God’s eyes because they were easy to listen to. The tritone is arguably the most dissonant interval we have, and the monks found its tension disturbing, dubbing it “The Devil’s Interval.”
It is used prolifically in West Side Story to illustrate tension between the Sharks and the Jets, and to express Tony’s lovelorn anguish in his song “Maria.” Composer Leornard Bernstein thought dissonance was basically the theme of the musical. It is used to build harmonic tension.
Black Sabbath is well known for bringing the tritone back into popular use. It was called “devil music” before guitar player Tony Iommi even realized what a tritone even was. Check out this melodic example from their 1969 song “Black Sabbath.”
Jimi Hendrix makes use of the tritone in his 1967 “Purple Haze” to represent the tense, frightening side of all those psychedelic drugs he loved so much. In this case, the tritone is manifested as an interval between the bass guitar and the electric guitar.
Music is perpetually inspiring emotion, but can it truly represent evil? As with most phenomena, the power lies not in the act itself, but in the hands of the performer.