Scales and Key Signatures
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Scales
A scale is a group of pitches (scale degrees) arranged in ascending
order. These pitches span an octave. Diatonic scales are scales that
include half and whole steps. The first and last note is the tonic. It
is the most 'stable' note, or rather the easiest to find. Because of
this, diatonic melodies often end on the diatonic note. The other notes
in the scale also have names. The second note is the supertonic. The
third is the mediant, halfway between the tonic and dominant. The
fourth note is the subdominant. The fifth note is the dominant. The
submediant is the sixth note. The subtonic is the seventh note in the
natural minor scale. The seventh tone of the major, harmonic and
melodic minor scales is called the leading tone if it is one half step
lower than the tonic.
The Major Scale
The major scale consists of seven different pitches. There are half
steps between the third and fourth and seventh and eighth scale
degrees; whole steps exist between all other steps. Below is a the C
major scale. The pattern of whole and half steps is the same for all
major scales. By changing the first note, then using the pattern as a
guide, you can construct any major scale. Likewise, if you know the
pattern for any other scale, you can create them, too.
The Natural Minor Scales
These scales have seven different scale degrees. There are half
steps between the second and third and the fifth and sixth degrees;
whole steps exist between all other steps. Shown below is the A minor
scale.
The Harmonic Minor Scale
This scale is the same as the natural minor scale, except the
seventh step is raised a half step. There is now an interval of one
half step between the seventh and eighth notes, and one and a half
steps between the sixth and seventh notes. This is a harmonic A minor.
The Melodic Minor Scale
This is another minor scale variation. In this scale, the sixth and
seventh notes are each raised one half step. All the patterns to this
point have been the same as one climbs and descends the scales. The
melodic minor scale, however, ascends with the modifications noted
above, but descends in the natural minor scale. This is a melodic A
minor.
Pentatonic Scales
Pentatonic scales, as their name suggests, have only five notes. To
get from one end of the scale to the other, they require gaps of more
than a half step.
Scales that do not follow the interval patterns of the diatonic or
pentatonic scales are called nondiatonic scales. Many nondiatonic
scales have no identifiable tonic.
The chromatic scale is a nondiatonic scale that consists of half
steps only. Because each pitch is equidistant, there is no tonic. A
whole tone scale is comprised of whole steps. Like the chromatic scale,
it too has no tonic. The blues scale is a chromatic variant of the
major scale. This scale contains flat thirds and sevenths which
alternate with normal thirds and sevenths. This alternating creates the
blues inflection.
Transposition
Scale patterns can be duplicated at any pitch. Rewriting the same scale pattern at a different pitch is called transposition.
Thus, if you used the major scale pattern, but started at G, you would
just have to count up according to the major scale pattern to transpose
it. All the notes of a piece can be modified in this way, by finding a
note's counterpart in the modified scale.
Since some notes will always be sharp once transposed or in certain
scales, it is sometimes helpful to place accidentals at the very
beginning of a piece in order to modify all the notes of a certain
pitch. Placing accidentals at the beginning of the music (as opposed to
right beside a note) allows the accidentals to affect every note in the
entire piece. So, placing a sharp on line F makes every F sharp. The
arrangement of sharps and flats at the beginning of a piece of music is
called a key signature.
Key Signatures
To help understand and remember key signatures, a chart called the
circle of fifths can be used. On the outside are the major key names,
separated by fifths. On the inside are the corresponding minor key
names. In the middle is the number and position of the sharps or flats.
There is a little trick to figuring out a key signature's name. When
confronted with a key signature that consists of flats, look at the
flat second from the far right. This flat is on the line or space the
key signature is named after. One flat is F, since you can't go to the
next -to-last flat. To find tthe name of a key signature with sharps,
look at the sharp farthest to the right. The key signature is the note
a half step above that last sharp.
Key signatures can specify major or minor keys. To determine the
name of a minor key, find the name of the key in major and then count
backwards three half steps. Remember that sharps and flats affect names.
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