Let’s return now to a bit more music theory as we establish a working vocabulary and an understanding of musical notation.

Playing consecutive notes in an octave (but not necessarily all of them) is called playing a scale. There are different types of scales defined in Western music, which vary in the notes played within an octave. These different types of scales are referred to as intonations.

Table 3.1 lists seven types of scales divided into three general categories – chromatic, diatonic, and pentatonic. A list of 1s and 2s is a convenient way to represent the notes that are played in each. Moving by a semitone is represented by the number 1, meaning “move over one note from the previous one.” Moving by a whole tone is represented by the number 2, meaning “move over two notes from the previous one.”

In a chromatic scale, 13 consecutive notes are played, each separated from the previous one by a semitone. A chromatic scale starts on any key and ends on the key which is an octave higher than the first. This is represented simply by the list [1 1 1 1 1 1 1 1 1 1 1 1]. Note that while 13 notes are played, there are only 12 numbers on the list. The first note is played, and then the list represents how many semitones to move over to play the following notes.

Eight notes are played in a diatonic scale. As with a chromatic scale, a diatonic scale starts on any key and ends on the key which is an octave higher than the first. In a major diatonic scale, the pattern is [2 2 1 2 2 2 1]. This means, “start on the first note, move over by a tone, a tone, a semitone, a tone, a tone, a tone, and a semitone.” A major diatonic scale beginning on D3 is depicted in Figure 3.8. Those who grow up in the tradition of Western music become accustomed to the sequence of sounds in a diatonic scale as the familiar “do re mi fa so la ti do.” A diatonic scale can start on any note, but all diatonic scales have the same pattern of sound in them; one scale is just higher or lower than another. Diatonic scales sound the same because the differences in the frequencies between consecutive notes on the scale follow the same pattern, regardless of the note you start on.

Figure 3.8 The key of D

Figure 3.8 The key of D

A minor diatonic scale is played in the pattern [2 1 2 2 1 2 2]. This pattern is also referred to as the natural minor. There are variations of minor scales as well. The harmonic minor scale follows the pattern [2 1 2 2 1 3 1], where 3 indicates a step and a half. The melodic minor follows the pattern [2 1 2 2 2 2 1] in the ascending scale, and [2 2 1 2 2 1 2] in the descending scale (played from highest to lowest note). The pattern of whole and half steps for major and minor scales are given in Table 3.1.

Table 3.1 Pattern of whole and half steps for various scales
Type of scale Pattern of whole steps (2) and half steps (1)
chromatic 1 1 1 1 1 1 1 1 1 1 1
major diatonic 2 2 1 2 2 2 1
natural minor diatonic 2 1 2 2 1 2 2
harmonic minor diatonic 2 1 2 2 1 3 1
melodic minor diatonic 2 1 2 2 2 2 1 ascending
2 2 1 2 2 1 2 descending
pentatonic major 2 3 2 2 3 or 2 2 3 2 3
pentatonic minor 3 2 3 2 2 or 3 2 2 3 2

Two final scale types ought to be mentioned because of their prevalence in music of many different cultures. These are the pentatonic scales, created from just five notes. An example of a pentatonic major scale results from playing only black notes beginning with F#. This is the interval pattern 2 2 3 2 3, which yields the scale F#, G#, A#, C#, D#, F#. If you play these notes, you might recognize them as the opening strain from “My Girl” by the Temptations, a pop song from the 1960s. Another variant of the pentatonic scale has the interval pattern 2 3 2 2 3, as in the notes C D F G A C. These notes are the ones used in the song “Ol’ Man River” from the musical Showboat (Figure 3.9).

Figure 3.9 Pentatonic scale used in “Ol Man River”
Ol' man river,
C   C     D F
Dat ol' man river
D   C   C     D F
He mus'know sumpin'
G   A       A       G   F
But don't say nuthin',
G     A   C     D   C
He jes'keeps rollin'
D   C   C         A   G
He keeps on rollin' along.
A   C     C     A   G   A F

To create a minor pentatonic scale from a major one, begin three semitones lower than the major scale and play the same notes. Thus, the pentatonic minor scale relative to F#, G#, A#, C#, D#, F# would be D#, F#, G#, A#, C#, D#, which is a D# pentatonic minor scale. The minor relative to C D F G A C would be A C D F G A, which is an A pentatonic minor scale. As with diatonic scales, pentatonic scales can be set in different keys.

It's significant that a chromatic scale really has no pattern to the sequence of notes played. We simply move up by semitone steps of [1 1 1 1 1 1 1 1 1 1 1 1 1]. The distance between neighboring notes is always the same. In a diatonic scale, on the other hand, there is a pattern of varying half steps and whole steps between notes. A diatonic scale is more interesting. It has color. The pattern gives notes different importance to the ear. This difference in the roles that notes play in a diatonic scale is captured in the names given to these notes, listed in Table 3.2. Roman numerals are conventionally used for the positions of these notes.   These names will become more significant when we discuss chords later in this chapter.

Table 3.2 Technical names for notes on a diatonic scale
Position Name for note
I tonic
II supertonic
III mediant
IV subdominant
V dominant
VI submediant
VII leading note