Tritones
Tritones
A Tritone is equivalent to 6 semitones or half steps.
By themselves, Tritones have a rather harsh, dissonant sound.
Tritones go by many names:
Flat 5
Diminished 5th
Sharp 4
Augmented 4th
The tritone is interesting because it exactly splits the octave into two parts.
An octave spans 12 semitones, therefore the tritone falls right in the middle because it spans 6 semitones.
In the Major Scale, tritones only occur from the 4th to 7th degrees, or from the 7th to 4th degrees.
That means in the key of C, they occur between B and F, or between F and B.
Any other occurance would mean sharps or flats would have to be added to the scale.