What is an interval of an eighth?

Answer 1

It's when between to notes, them included, of a scale, you can count 8 notes.

Example:

- on C major

C1 and C2 (or any other Cn and Cn+1) have an interval of an eighht - also called an octave.

C D E F G A B C

1 2 3 4 5 6 7 8

- on E major

E F# G# A B C# D# E

1 2 3 4 5 6 7 8