Two-Beat Bass Lines
One type of bass pattern that is used in blues and jazz is the two-beat bass line. You've actually encountered it before with previous bass figures that used the movement from root to fifth on beats one and three. That is one version of the two-beat feel. A two-beat bass line can use other notes and rhythms as long as beats one and three are emphasized and beats two and four are left more or less empty. Also, a swing feel may be incorporated through the use of skip notes that directly precede beats one and three. Through variation and randomization you can make a simple two-beat line more attention grabbing.
Figure 8-5 provides a two-beat swing line. In the first four measures you will play the two-beat line straight without skip-note ornamentation. For the last four measures you'll play the same bass line but with skip notes added. This type of two-beat groove is often used to give a restrained feel to a jazzy song. It may also be used to give the song a bouncy, carefree feel.
Often, two-beat bass lines will be used at the beginning or head of a slow jazz tune. After playing the head, the bass and rhythm section may decide to escalate the intensity of the music by switching to a heavier swing feel such as a shuffle or a walking bass line.
In jazz, what is the “head”?
The term “head” refers to the melody of a jazz tune. Usually the head is played at the beginning and at the end of a song. After the head is played, soloists take their turn improvising over the chord changes.
Once the soloing is complete, it's customary to play the head once again before bringing the tune to a close.
Since jazz and blues are highly improvisatory, you will need to come up with bass lines on the fly. You will also need to use listening skills to decide what type of bass part (shuffle, two-beat, walking) is most appropriate. You may be able to experiment with these possibilities at a jam session or some other less formal musical setting where improvisation, spontaneity, and experimentation are normal and, in fact, expected.