Musical Virtuosity and Creativity - Computers and Creativity - page 121

Fig. 5.5 A diatonic side-slip invented by Coltrane. This particular side-slip is such that it actually
does not create any harmonic tension, as the transposed motif (up 1 semitone) stays, miraculously,
in the tonality (here, one minor third above)
Fig. 5.6 A tricky example of a 'reverse side-slip' by Al Di Meola in a chorus on Guardian Angel
(GuitarTrio 1977 ). The two first phrases are transpositions, (2 then 1) semitones lower, of the last
one, which is in the right key, thereby creating a stunning resolution effect, only made possible by
speed (here, 184 bpm)
instance, Fig. 5.5 shows a diatonic side-slip invented by John Coltrane (and used
extensively e.g. on his improvisations on Giant Steps ). This is a nice 'trick', or
rather a small theorem of tonal music: when a motive in some major key (say, F)
is transposed up 1 semitone, it is most of time in the initial key transposed 1 minor
third up (here, Ab7).
The difficulty for improvisers is not only to produce the slide-slip, but to re-
establish continuity during the re-entrance phase. This necessitates tricky planning,
as the final notes of the transposed pattern are, usually, precisely out of key, so no
natural continuation may be in the musician's hands.
We will see how our framework copes with side-slipping in a general way, by
allowing side-slips to be inserted smoothly in the generated chorus while keeping
continuity.
5.2.5 Virtuosity Is to Improvisation as Running Is to Walking
Virtuosity is about speed, but not only speed. Beyond speed—innate for com-
puters—virtuosity is the capacity to play interesting phrases fast, and make them
appear as singular solutions to a difficult problem, much like a magician tirelessly
extracts rabbits from a shallow hat. Like running is not walking faster (Cappellini
et al. 2006 ), playing virtuoso phrases calls up cognitive skills and motor mecha-
nisms that differ from the ones used in standard improvisation, which consists ba-
sically of paraphrasing the original melody (Baggi 2001 ). In this view, virtuosity