Music Theory (Level : Basic) - Part 1 : Intervals

This article was originally written by Eowyn. It is going to be published part by part in DTB, to help the guitarists over the world to learn music theory in details.

Theory
Intervals aren’t much fun to learn but they are essential and we'll need them:
• in the context of scales
• in order to define chords
• to help in analysing phrases and solos
and most importantly, we absolutely need to know how to play them. So please, bear with me and
read on.
As you probably know, the whole western musical system is built on 12 notes:

Some points worth noting:
• Some notes have two names (e.g. C# - "C sharp", or Db - "D flat"). This is required
for theoretical reasons that we will not go into but in practice they are one and the
same note.
 
• This ordered sequence of notes is called a scale; this particular one is the
"chromatic scale". We'll get into scales in future topics.
 
• Between any pair of consecutive notes in the scale above, there is an equal
distance of a halftone (H); two halftones form a whole tone (W). Because of that
equal distance of a halftone, this scale is called equal-tempered. Why there are
only twelve notes and why there is that equal distance of a halftone between any
pair of adjacent notes is a very complex subject that we won’t go into here.
 
The "distance" between two arbitrary notes is called an "interval".


To be continued...