By definition atonal, these non-diatonic scales would seem to have little use for musicians improvising over traditional harmonies. They create their own language and harmonic environment but they can also be used to alter common harmonic situations. This seems a logical place to start.
Just as any five-note scale qualifies as pentatonic, any four-note scale is tetratonic. Here however, we will use the symmetrical tetratonic scale based on the tritone.
There are six different tritone intervals (counting the inversions), and from each a different tetratonic symmetrical scale can be built. Here are the six different scales.
First let’s look at some logical fingerings of the scale. Three possible left-hand fingerings are given.
Another fingering uses consecutive, or legato, picking.
This is a triplet line based on the tetratonic scale, using consecutive, or legato, picking.
This line separates the two tritone pairs found in the tetratonic scale.
This line combines the shapes from the previous example.
Rhythmic interest can be achieved by playing three-note groups as eighth notes.
Here a melodic pattern is created when a motif (melodic fragment) from the scale is sequenced downward by a tritone. All notes remain within the scale.
In this example the four-note scale is sequenced upward by tritones. Beginning a line on an upbeat can help create rhythmic interest.