THE MINOR SCALE.
There are two forms of minor scales, harmonic and melodic, both differing in construction from the major form.
The minor key having no sharps or flats in the signature is a. Starting at a and sounding the seven white keys in order to the right produces a form of scale with whole steps between 1 and 2, 3 and 4, 4 and 5, 6 and 7, 7 and 8, and half steps between 2 and 3 and between 5 and 6. This scale is unsatisfactory to the ear as its subtonic is not a leading tone. The effect of a leading tone should be urgent, restless, and demand its tonic in order to obtain a restful effect. This urgent effect can only be obtained by the subtonic being one half step below the tonic. This may be obtained by simply raising the seventh one semi-tone in the above scale formation and thus is produced the so-called harmonic minor scale.
The symbols for raising a note are the sharp (#), the double sharp (x), and the cancel (⊄) (also called natural) when placed before a note that has been previously affected by a flat. The symbols for lowering a note are the flat (b), the double flat (bb), and the cancel when placed before a note that has been previously affected by a sharp. By these statements it can be seen that the cancel (⊄) is both a lowering and a raising symbol. The cancel lowers a tone when it cancels a sharp and raises a tone when it cancels a flat.
The harmonic minor scale is formed by whole steps between 1 and 2,—3 and 4,—4 and 5,—half steps between 2 and 3,—5 and 6,—7 and 8, and an interval of one and one-half steps (called an augmented step) between 6 and 7. In demonstrating the minor keys, a curved line will be used to connect those figures representing tones one half step apart and a bracket to connect those figures representing tones an augmented step apart.
The key of a minor (harmonic form) is as follows:—
a b c d e f g# a
1 2 3∼4 5∼6∪7∼ 8
The student will notice that this scale has one sharp (g). Nevertheless, the a minor is the minor key which has neither sharps nor flats in its signature. The raised seventh of all minor keys is never present in the signature, but appears as accidental.
When a sharp, double sharp, flat, double flat or cancel, which is not present in the signature, is placed before a note, it is called an accidental. If the raised seventh were present in the signature, uniform signatures in the minor would be impossible. It may also be remarked here that the seventh is not always raised during the course of a composition and is necessarily raised only when the composer desires the listener's ear to come at rest on the tonic, in which case the tonic must be preceded by the raised seventh, if the subtonic precedes the tonic in the melody or harmony.