Digital Sound & Music: Concepts, Applications, & Science, Chapter 3, last updated 6/25/2013
The key signature for a harmonic minor key is the same as the natural minor. What turns
it into a harmonic minor key is the use of sharps or naturals on individual notes to create the
desired pattern of whole tones and semitones. To create the pattern[ 2 1 2 2 1 3 1] (harmonic
minor) from [2 1 2 2 1 2 2] (natural minor), it suffices to raise the seventh note a semitone.
Thus, the scale for a harmonic minor is notated as shown in Figure 3.19. (In this section and
following ones, we won't include measures and time signatures when they are not important to
the point being explained.)
Figure 3.19 A minor harmonic
Similarly, the melodic minor uses the key signature of the natural minor. Then
adjustments have to be made in both the ascending and descending scales to create the melodic
minor. To create the ascending pattern [2 1 2 2 2 2 1] (melodic minor) from [2 1 2 2 1 2 2]
(natural minor), it suffices to raise both the sixth and seventh note by a semitone. This is done by
adding sharps, flats, or naturals as necessary, depending on the key signature. The descending
pattern for a melodic minor is the same as for the natural minor – [2 2 1 2 2 1 2]. Thus, the notes
that are raised in the ascending scale have to be returned to their normal position for the key by
adding sharps, flats, or naturals, as necessary. This is because once an accidental is added in a
measure, it applies to the note to which it was added for the remainder of the measure.
F minor melodic is notated as shown in Figure 3.20. In F minor melodic, since D and E
are normally flat for that key, a natural is added to each to remove the flat and thus move them
up one semitone. Then in the descending scale, the D and E must explicitly be made flat again
with the flat sign.
Figure 3.20 F minor melodic
In E minor melodic, a sharp is added to the sixth and seventh notes – C and D – to raise
them each as semitone. Then in the descending scale, the D and E must explicitly be made
natural again with the sign, as shown in Figure 3.21.
Figure 3.21 E minor melodic
22.214.171.124 The Circle of Fifths
In Section 3.1.5, we showed how keys are distinguished by the sharps and flats they contain.
One way to remember the keys is by means of the circle of fifths, a visual representation of the
relationship among keys. The circle is shown in Figure 3.22. The outside of the circle indicates
a certain key. The inner circle tells you how many sharps or flats are in the key.