Although you might see bass charts with every note written out, it is more common to see chord changes or a mix of chord changes and written out bass lines. When a chart is made up of chords, with or without a melody, it is often referred to as a lead sheet. Lead sheets are condensations of a given piece of music. Often, lead sheets are used to represent popular tunes. When reading a lead sheet, it's assumed that you will not attempt to duplicate a given arrangement or recording note for note. Rather, you will recreate the overall feel or gist of the tune. Lead sheets are used extensively in jazz where the performers improvise over the melody and chord changes of a tune. One thing's for sure, lead sheets encourage — indeed require — interpretation and spontaneity.

If you need to come up with an improvised bass line, first try to determine the basic style. Ask yourself if it is a rock tune, a Latin tune, a funk tune, a swing tune, a country tune, or a blues shuffle. Within these styles there are further refinements. If it is a rock tune, is it a hard rock song or a pop ditty? If it is a funk tune, is it a Motown style or modern slap-bass style? Luckily, you'll often find the style listed at the top left of the chart.

Once you know what style you're playing, your creative impulses and musical habits need to kick in. You'll have to be able to turn chord changes into compelling bass lines and licks on the spot! If you don't know where to begin, start simple. Remember to listen to the drummer, rhythm section, and the entire band in order to lock into the tempo and groove. As the tune progresses, you can always evolve your approach to include fancier lines and licks. But at first, keep it simple. Also, if you're toggling between written lines and improvised chord sections, you need to stay alert, otherwise you will miss sudden shifts or changes in the music.

Improvising over a chart is difficult because you are reading music as you play. When you are sight-reading and attempting a solo, it is not necessary to turn every chord change into a new melodic line or lick. Instead, play through the changes. By emphasizing the key center and the important chords, you can simplify the harmonic content that you are basing your solo on. Often, one or two scales are sufficient in partnership with the chords. Figure 16-2 shows how this may be done. The chords are complex, but a one-scale-fits-all approach actually works. With some practice and experience, you will develop the ability to simplify the chords in a chart until you find the harmonic and melodic common denominators.

Figure 16-2.

Simplifying complex chord changes in a chart