My definition of guide tones is the third and seventh of a chord. While I
was at the Universiity of Southern California getting my Master's Degree in
Performance Studio/Jazz Guitar, my teachers referred to them equally for
harmonic voicing use as well as melodic. In other words, the Lenny Breau
approach of playing two note voicings as a counterpoint to the melody fits in
my definition of guide tones as well. I did not hear the phrase, "Shell
voicings" until more recently. Guide tones to me simply mean the essential
notes necessary to convey the chord's basic quality (the root of the chord
being taken care of most often by the bassist).
Using the definition of melodic guide tones only, some examples I can come up
with are the typical triadic blues riffs (in F for this example) which
remain the same over the I7 chord as they do over the IV7 chord with the
exception of the A (third of the I7) chord becoming Ab (b7 of the IV7) over
the IV7 chord, this can be found on numerous Charlie Parker solos, a well
known one is his solo on "Now's The Time" on Verve.
As to whether they are conscious of their use of guide tones while soloing,
all performing artists (dance,acting, music, etc.) seem to perform their
best when it happens at a sub-conscious level. The musician becomes unaware
of his/her instrument's techniques and physical environment and just
"speaks" their ideas through their instrument. Often the performer is
surprised at how quickly the time of the gig passes and is not able to tell
anybody what was on his mind during any of the solos. When we drive our
brain enters a similar state, waking us up in emergencies but mostly
remaining in a relaxed state of awareness as we think of other things and our
bodies react to the physical tasks of coordinating our foot and arm movements
(how many people can remember every sign post on a familiar route they just
drove?).
My point is that practicing is when people think of guide tones, target
notes, altered scales, outlines, fragmentation, augmentation,diminution, and
other theoretical concepts. If they are practiced enough they become muscle
memory just like major scales have to in the beginning. When soloing,
conscious thoughts of those concepts just tend to get in the way and stop
the natural flow of music. I think of guide tone practicing as something
which helps me in learning a tune with difficult harmonies so I can get
"inside" the chord changes, but I don't imagine they even enter my thoughts
when I am on a gig.
Brian Oates