[This post is the third in a series on Introductory Music Theory. The series begins with A Musical Theory. The previous post in this series is Stepping Into Numbers.]

The interval of an octave is a pretty amazing thing. When we sing the Do-Re-Mi scale it seems perfectly reasonable that the eighth note is called “Do” again because, as one could say, “it sounds just like the first Do only higher”. (By the way, if an octave doesn’t sound this way to you, it’s may be time to consider poetry or painting as your artistic endeavor instead of music.) Of course you can sing Do-Re-Mi past the second Do, ever higher to the third Do, and as you do so each successive note is exactly an octave above the earlier one of the same name. So Mi to Mi (3 to 10) is called an octave just like Do to Do (1 to 8). As I mentioned in the last post, all of the interval names – 2nd, 3rd 4th, 5th, etc, refer to a specific number of half-steps no matter what the starting point is. The interval of a 2nd gets its name from the distance between 1 and 2 on the Major scale (1 step). Since the interval from 6 to 7 is also 1 step, we can also call it a 2nd. Continue reading →