7. SOME RULES OF THE GAME CONCERNING H.S.U. DIVISION
We
are now equipped with the tools that enable us to proceed with the division
of the tonal discourse into H.S.U.'s, but first it is necessary
to learn a few rules of the game:
1) In case of
ambiguity regarding the point of division (for example, does the H.S.U. end with V or
with the I following V?), we must consult the other organizational
parameters of the musical discourse (formal context, phrasing, abrupt
changes of dynamics, texture, or figuration, etc.)
2) The
last term of an H.S.U. may coincide with the first term of the
following H.S.U. - for example, in a case where both H.S.U.'s are part
of the same musical event (phrase or phrase member) or following an
evaded cadence (such as a principal dominant followed by a secondary
dominant)
3) We may find a repetition of 2 consecutive terms within an H.S.U.
for example: III - VI - III - VI - II - V - I (we note that III - VI is repeated)
4) When determining the H.S.U.'s, always continue until I (or a substitute
of I) unless dissuaded by an indication from another parameter (for
example, a clear half-cadence)
5)
All H.S.U.'s contain V (in the role of a principal dominant), except in
the case of plagal H.S.U.'s such as I - IV - I or VI - IV - I
6) An H.S.U. may contain only one function; this would necessarily be the
function V (principal dominant) and the H.S.U. would usually be
followed or preceded by another H.S.U. which confirms the function V as
the principal dominant in a more explicit manner
7) In
the case of a non-modulating harmonic sequence other than one which
reproduces the fundamental structure (a descending circle of fifths), it is
possible for the H.S.U. to contain the function V (as principal
dominant) more than once because, exceptionally, and only in this
case, the H.S.U. encompasses the model of the sequence, the reproductions
of the model, and the closing formula. However, in the case of a
sequence that articulates the fundamental structure (which will later be
classified as a type 1 sequence), it goes without saying that there will
be as many H.S.U.'s as there are cycles of the the circle of fifths.
Having
concluded the presentation of this model of analysis for the tonal
harmonic discourse, explained in detail the theory of constants, and
specified the rules of the game, we are finally ready to tackle the
procedure for division into H.S.U.'s.
To begin, we
will apply it to the first prelude of the Well-Tempered Clavier, volume
I, by Johann Sebastien Bach, a prelude which opens an eminently
significant corpus and bears the constants which have been the object
of
this research. For the time being, we will adopt a modulating
perspective
(tonal plan: C major - G major - C major) in order to keep the context
of the entire corpus in mind (the other 23 preludes all modulate). Then
we will apply this technique of division to a waltz by Schumann (no 4
from op. 24), another modulating context (tonal plan: A minor - F major
-
A minor). Each of these two pieces will first be heard in its
entirety, then fragmented into H.S.U.'s in such a way so as to clearly
demonstrate the intrinsically tonal nature of these units.
