When the notes are played sequentially, the interval is called "melodic".When they are played simultaneously, it is called"harmonic".

The name of an interval depends on the number of notes it contains, including the end notes; for example, the interval C - F contains 4 notes (C, D, E, F), and will be called a “fourth”. The type of an interval depends on the number of H's and W's that it contains. An interval can be "minor" (m), "major" (M) or “perfect” (P); in addition, intervals can be “augmented” (aug or # or +) (raised by an H) or “diminished” (dim or b) (lowered by an H). When nothing is specified, the interval is considered to be major or perfect.


Here's a table of the intervals you should know:



The “8” is not called a perfect eighth but a perfect octave or simply octave. Intervals can span more than one octave. A "9th" is a 2nd an octave higher, an "11th" in a 4th an octave higher and "13th" is a 5th an octave higher. I've never seen intervals larger than a 13th being used in practice... and in blues and rock music, you'll rarely need more than the m7.

And finally this: make sure you know the difference between a "chromatic" H and a "diatonic" H:

• A chromatic H is when you raise (or lower) a note by an H without changing its name. For example, C - C#, Db - D, Gb - G, A - A# are all chromatic intervals.
• A diatonic H is when you raise (or lower) a note by an H and change its name. For example, C - Db, C# - D, F# - G, A - Bb are all diatonic intervals.

Please note: C - C# is musically identical to C - Db... but not theoretically. Damn theorists!

To be continued...