Tritone
Six semitones, exactly half an octave. Symmetric and ambiguous — up or down, it sounds the same. The old diabolus in musica.
6 semitones Symbol TT Dissonance
Listen
See
C
E
B
G TT
D 0
A
E
0 1234567
C → F♯
Where you have heard it
Ascending
Maria (West Side Story) the first two notes
Os Simpsons opening theme
Descending
Black Sabbath opening riff
What it gets confused with
Frequently asked
How many semitones is a tritone?
Six — exactly half of the octave, which is why it sits between the fourth and the fifth.
How do I recognise it by ear?
It is the first two notes of "Maria" from West Side Story and of The Simpsons theme: restless, asking to move.
Why is it called a tritone?
Because it spans three whole tones. It is also the only interval that inverts into itself — six semitones up or down give the same tritone.
There is an exercise track dedicated to recognising this by ear.
Train this