interval
B major seventh
BlowerA♯upperM711 half steps
Eleven half steps: a half step short of the octave, which is why it leans on it.
On the keyboard
What is true of it
B up a major seventh is A♯: 11 half steps, and 7 letters counting both ends.
Turn it upside down — put the B on top — and it becomes a minor second. The two numbers always add to nine, and the two sizes to twelve.
It is a dissonance.
Every interval on B
B → Cminor second · dissonanceB → C♯major second · dissonanceB → Dminor third · imperfect consonanceB → D♯major third · imperfect consonanceB → Eperfect fourth · perfect consonanceB → E♯augmented fourth · dissonanceB → Fdiminished fifth · dissonanceB → F♯perfect fifth · perfect consonanceB → Gminor sixth · imperfect consonanceB → G♯major sixth · imperfect consonanceB → Aminor seventh · dissonance