Part 4 of our series finds Simon Trask walking the (bass)line...

So far, the path we've cleared for ourselves through the musical undergrowth has taken us from simple root-note basslines through basslines which confine themselves to the first, third and fifth notes of each harmony (the basic triad chord) on to basslines which introduce the sixth and the flattened third for added colour. This month we're going to look at that staple of jazz bass playing, the 'walking' bassline - and discover that there are yet more notes we can use to 'underpin' each chord in a chord progression. Don't worry, I'm not about to foist lots of weird jazzy chords on you - we'll stick to dominant sevenths for the moment (for instance, C-E-G-Bb, F-A-C-Eb, G-B-D-F).

If your keyboard will let you, set up a splitpoint at D/Eb immediately above middle C, then assign an acoustic bass sound to the left and an acoustic piano sound to the right of the splitpoint. Now you can hold down a piano chord while playing the bassline on the good ol' string bass. In this month's examples there's a chord change every bar, so you could start out by simply sustaining each chord through the bar to get a feel for the harmonic interaction of chord and bassline. Then, when you've got used to that, try making the rhythmic interaction more interesting by adopting a more staccato ('chopped') style of chordal playing and throwing in chordal stabs on the fourth semiquaver of selected beats.

As with the boogie woogie basslines last month, there isn't any specific tempo at which a walking bassline should be played, so I haven't assigned a tempo setting to any of the examples - just take them at a tempo you feel comfortable with. Obviously a leisurely stroll across the keys will produce a different effect to that of a breakneck race - the former sounds cool and slinky, the latter hot and excitable!

But enough of that... Without further ado, let's get into Example 1. Straightaway you can see that the walking bassline consists of a regular succession of quarter notes - if you like, a regular pulse or 'heartbeat' around which the other musical parts can provide all manner of rhythmic variation. This differentiation finds a parallel within the jazz drum kit, where the drummer plays a steady rhythm on the ride cymbal and throws in syncopations on the kick, snare and toms. The melodic shape of the bassline consists of a smooth rise and fall, moving from one root note (C) to another (G) then (if we take this as a repeating 2-bar loop) back to the first root note again. In each case, the root note is on the first beat of the bar.

But how do the notes in each bar relate to the harmony of the accompanying piano chord? In bar one, the C and E are part of the C7 chord, but the F and F# certainly aren't. Think of the latter two as 'passing notes' between two chordal notes (E from CEG and G from GBD ie. the chord in bar two). Here the F# isn't even part of the key - hence it's also what is known as a 'chromatic' note. Strictly speaking, the F# in the bass clashes with the G in the C7 chord, but given its passing nature we experience this at most as a momentary 'enrichment' of the harmony (as in 'added spice'!). It could be said that the F# actually produces a change in harmony on the fourth beat, so that the chord is no longer C7 - but let's not get bogged down in harmonic analysis! If it sounds good, do it.

In bar two of Example 1, the bassline simply descends through the scale, going from root (G) to fifth (D) via the seventh and sixth. The overall movement is from one root (G) to another (C in the 'next' bar).

Example 2 introduces two new elements to Example 1's bassline. First, there's the octave leap up from C to C. The higher pitch coupled with the characteristic offbeat 16th note gives the second C a strong syncopated feel, yet the overall steady procession of quarter notes preserves the 'walking' sensation. The last note in this example, the Db (a semitone lower than D), is another chromatic passing note; its rhythmic and melodic effect is to accentuate the move to the root note of the next bar.

Example 3 adds another two bars to Example 2 in order to show how the walking bassline can be varied even though the harmonies remain the same. In bar four, the A is a passing note and the A# a chromatic passing note between the chordal notes G and B. Of course, if you want a riff effect then there's no reason why you shouldn't simply repeat bars one and two over and over. However, if you want to achieve the natural fluidity which is characteristic of the walking bass style then you need to introduce these sorts of changes - and the best way to do it is spontaneously, having first acquired a feel for the inflections, cadences and syntax of the walking bass 'language'. There really are numerous ways in which you can move from one root note to another using a combination of chordal and passing notes. How you use them is down to your feel for the evolving 'shape' of the bassline over a number of bars.

Example 4 illustrates a walking bassline for a different chord progression, in this case C7-F7. Here the C and E in bar one are chordal notes, the D and D# respectively passing and chromatic passing notes. Bar two features a scalic descent from F to the C in the 'next' bar, with the D and Db as passing and chromatic passing notes respectively. The Eb is the 7th in F7, but if you consider only the three triadic notes (here, F, A and C) as chordal notes then it's also a passing note.

Example 5 illustrates another possible walking bassline for the C7-F7 progression. In bar one the Gb is a chromatic passing note, while in bar two the two Bs are passing and chromatic passing respectively. Incidentally, for those of you who are still learning music notation, the sign in front of the second B is known as a 'natural' - in this instance, it returns the B to its 'natural' state, ie. neither sharpened nor flattened.

Example 6 illustrates one possible way in which the bassline in Example 5 could 'evolve' over another two bars. Notice here how the B natural in bar two rising to C is replaced in bar four by the D and Db falling to C.

Finally, Example 7 applies some of the 'shapes' we've learnt to a longer chord progression based on the 'cycle of fifths' (so called because the root progressions are in fifths and eventually you get back to the first chord again). Here the cycle is cut short by the semitone rise from Gb to G natural in bars seven and eight, as the G then progresses naturally back to the C of bar one. Notice here how bar two 'parallels' bar one in shape, bars five and six parallel bars three and four, and bar eight parallels bar seven. Those of you who haven't got beyond the key of C yet may find Example 7 a bit of a shock to the system, but keep on persevering - it can only get easier!

Expect more jazziness to come - all in the name of laying a solid bas(s)is, of course!