,
we are uncertain of the exact nature of the seventh scale degree and, for
that matter, of the key. However, if we maintain the cross-relation in the
same voice, the ambiguity resolves itself in the voice leading.
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In the proper context, we may raise both the sixth and seventh scale degrees of a minor key.
In successive harmonies, if the same
scale degree appears in two different forms, we have a cross-relation.
When, say,
,
we are uncertain of the exact nature of the seventh scale degree and, for
that matter, of the key. However, if we maintain the cross-relation in the
same voice, the ambiguity resolves itself in the voice leading.
As a rule, you should avoid cross-relations except when they arise in a single voice, as they do in each of the three excerpts of example 9-1.
Ex. 9-1--Cross-relations in Chorale Style
In free style, composers often use the cross-relation between outer voices for dramatic effect.
Ex. 9-2--Brahms, Symphony No. 3, first movement
Each measure of example 9-2 gives us a new version of the third scale degree (A). We can follow the changes from one measure to the next until, in the fourth measure, the A-natural in the highest voice shifts to the A-flat in the lowest.
A special ambiguity surrounds the
seventh scale degree. When do we raise
and when
do we leave it unaltered? The answer is quite simple and direct.
Ex. 9-3--Leading Tone in the Minor
Raise
whenever
it acts as leading tone--that is, whenever it moves to
. Therefore,
raise in
any cadence to the minor tonic (see example 9-3a). Raise
at the half
cadence as well, for the terminal V will, eventually, resolve to i (see example
9-3b).
Use the unaltered, or diatonic, version
of when
descending from
through
to
(see example
9-3c, the first two alto notes).
Raised
offers no
advantage when descending to
. In fact,
the augmented second that results from a raised
- motion is a melodic dissonance.
Avoid melodic augmented seconds. In
the minor,
moves naturally to
. It is only
a half step away. Raised
moves naturally
to for the
same reason.
Remember: Unaltered
descends
to and raised
ascends
to .
Clearly, the motions
-raised
and raised
-which create
the augmented second contradict the natural voice leading tendencies of the
scale degrees involved.
The simplest way to avoid the augmented
second is to approach and leave the raised seventh scale degree from above.
As a rule, raised
should either
move directly to
or should
move to another scale degree that does. For example, we frequently see the
melodic progression raised
-
- in the minor.
Similarly, you should remember that
the raised
arises from our effort to avoid the augmented second (See Chapter
3, the "Melodic Minor"). When passing from
to
in the minor,
we require raised
--and raised
to approach
raised .
If you must approach raised
from below,
do so from raised
.
Ex. 9-4--Bach, Chorale 57
As a voice moves up by step
toward ,
Bach raises
to create the leading tone and raises
to avoid
the augmented second. When a voice moves down by step from
to
, Bach leaves
both and
unaltered.
When a voice skips from raised
, the augmented
second is not a concern (see the final tenor G-sharpof example 9-4).
The dissonance created by altered notes in the minor can, in special instances, provide dramatic contrast to our free flowing voice leading. Though more common in free style, such exceptional voice leading has its place even in chorale style.
Recall that all melodic dissonances, like harmonic dissonances, require resolution. Diminished intervals resolve inwards--that is, in the opposite direction of the skip. Augmented intervals resolve outwards--that is, in the same direction as the skip (see Chapter 3, "Active Intervals").
We see in example 9-5 three dissonant skips to the raised seventh scale degree, each in the bass. Notice the similarities.
Ex. 9-5--Linear Dissonances in the Bass
First, each example descends to
raised ,
creating a diminished interval.
Second, the leading tone of each example
resolves to
. This
motion "resolves" each of the dissonant intervals to a consonant
interval.
Third, the dissonant skip in the bass is balanced by a step in the soprano, usually in the opposite direction.
As you learned in chapter 5, a
skip--especially a dissonant one--should be followed by a step in the opposite
direction. Recall that diminished intervals resolve inwards, diminished skips
resolve naturally by step in the opposite direction, creating just that preferred
voice leading. For this reason, we see diminished melodic intervals more
frequently than augmented melodic intervals.
In the minor, we alter scale degrees to avoid the natural pull of the minor mode toward its relative major. As the relative major of each minor key, III is a potential tonic.
Ex. 9-6--Diminished ii and Tonicized III
The major has a single naturally occurring
diminished triad, vii. It functions as a voice-leading triad (almost always
in 
position)
to I or I6. The diminished triad on ii in the minor poses a special problem.
It will pull toward III, for the moment making it sound like a tonic. We
call this process tonicization.
We may use diminished ii in first inversion as a passing chord to V# (see example 9-6a).
Avoid any diminished triad in root position, however. Root position emphasizes the (dissonant) diminished fifth above the bass. For this reason, diminished-ii cannot function adequately as the upper-fifth divider of V. (Root-position diminished triads arise frequently in the diatonic sequences discussed in Chapter 16, however.)
Just as vii resolves naturally to I in the major, diminished-ii resolves naturally to III in the minor. This tonicization of III poses a challenge to the minor tonic (see "Tonicized III" below).
Similarly, the major triad on (unaltered)
easily takes
on the appearance of an upper-fifth divider of III. The resulting VII-III
progression, however, mimics the V-I progression of the relative major. This,
too, creates tonal ambiguity and a momentary tonicization of III, the relative
major.
In example 9-6b, Bach supports the
bass passing note between
and
with a VII6.
This major triad sounds, for the moment, like V6 in the key of F-major (that
is, the key of III). Thus the VII6-III in i (D minor) sounds like V6-I in
III, (F major). The C-C-sharp cross-relation of the alto
(-#) immediately draws us back into D
minor (i), however, creating a V4/3 passing dominant to the true tonic.
When using VII as upper-fifth divider of III, be aware of this implicit tonicization of III.
For the minor tonic to remain tonic, you should tonicize III only when the voice-eading function of III in relation to its minor tonic is clear. For this reason, we find III tonicized most frequently when it functions as the third divider of the progression i-V# or when III substitutes for i6 in a prolongation of i.
In a i-III-V# progression, you can
prolong the motion from i to III with a passing VII
that tonicizes
III. If, then, you move directly from III to V#, you create a cross-relation
between the
unaltered-
of III and the raised
of V#. Thus,
a ii often
passes between III and V#. If, however, you move directly from III to V#,
you should keep the cross-relation
(-#) in the same voice (see example 9-6b).
In free composition (and, on occasion, in chorale style), the tonicization
of the third divider can be extensive.
Ex. 9-7--Bach, Chorale 13
Here, Bach tonicizes III with the
same i-VII6-III progression. This sounds like V6-I in III (C-major). Bach
prolongs this III with a III6. (At the moment, this sounds more like I6 in
C major than III6 in A minor.) The voice-leading bass F-sharp that begins
the last measure destroys the tonicization. Bach reestablishes tonic A minor
with a contrapuntal cadence to i, approached in the bass by a raised
-raised
- linear progression.
We will discuss tonicization techniques
more thoroughly later.
. When
approaching the raised seventh scale degree, avoid the augmented second between
raised and
.
Remember that both the diminished triad on ii and the major triad on VII can tonicize III. A tonicization of III need not compromise the minor tonality as long as III functions clearly as a voice-leading prolongation of the minor tonic.
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