The blues scale centers on blue notes. The most important blue notes are the flatted third and the flatted seventh. See FIGURE 5-1. In the key of C major, this would be E-flat and a B-flat, respectively. In the key of C major, an E-flat is a minor third and a B-flat is a minor seventh.
Tri-tones are very dissonant. Because of its jarring sound, this interval used to be called
The other blue note found in the blues scale is the flatted fifth. In some contexts, this interval is also written as an augmented fourth or sharp eleven. In the key of C major, the flatted fifth is a G-flat. When juxtaposed against C, the interval becomes a tri-tone.
FIGURE 5-1: Blue Notes
Early blues does not focus on the flatted fifth. It was occasionally used as a passing tone between the perfect fifth and the perfect fourth, or vice versa, but musicians rarely lingered on this note nor did they end phrases with it. However, jazz musicians, particularly bebop artists, made extensive use of this interval in the late 1940s and 1950s. For example, pianists such as Thelonious Monk regularly used the flatted fifth. FIGURE 5-2 shows you a jazzy phrase with flatted fifths. This phrase mimics Monk's playing style.
The other notes in a basic blues scale include the tonic, the perfect fourth, and the perfect fifth. If you put all of these intervals together, the blues scale emerges. FIGURE 5-3 shows you the basic blues scale written in C major.
FIGURE 5-2: Using Flatted Fifths
FIGURE 5-3: Basic Blues Scale
While the basic blues scale is useful, it is also limited. For example, a major third is often used in conjunction with the flatted third. FIGURE 5-4 shows you this movement in the key of C major. Here, an E-flat slides into an E-natural.
FIGURE 5-4: Minor Third-Major Third Lick
Due to the limitations of the basic blues scale, a more comprehensive blues scale is needed to show the relationship between blue notes and other chord tones. In this scale, major second, major third, and major sixth scale degrees have been added. This is illustrated in FIGURE 5-5.
FIGURE 5-5: Full Blues Scale
Memorize both the basic and the full blues scales. These scales will come up time and time again in this book. You will also make use of them in the blues study pieces found in Chapter 15.