Semicadence
Any deviation from the formula of the perfect
cadence--either in the choice of some other than the tonic chord, or in
the omission of the keynote in either (or both) of the outer
parts--weakens the force of the interruption, and transforms the
cadence into a lighter, more transient, point of repose, for which the
term semicadence (or half-stop) is used. The semicadence indicates
plainly enough the end of its phrase, b
t does not completely sever it
from that which follows.
It is these lighter, transient forms of cadence to which a number of
different names are given; for the student of analysis (and the
composer, also, for that matter) the one general term semicadence, or
half-cadence, is sufficient, and we shall use no other.
If, then, a cadence is final in its effect, it is a perfect one; if
not, it is a semicadence. The harmony most commonly chosen as the
resting-place of a semicadence is the chord of the dominant,--the
fifth step of the momentary key,--that being the harmony next in
importance to that of the tonic (the one invariably used for the
perfect cadence). The following example illustrates the dominant
semicadence:--
The cadence-chord is the dominant harmony (root e) in the key of A
minor; neither of the two upper tones on the first and second beats is
the root of the chord; it is quite sufficient that the root appears as
lowermost tone, and even this is not necessary. The point of repose
is shifted to the second beat, in the manner so amply illustrated in
the examples of the disguised cadence; the methods we have seen may be
applied to any kind of cadence.
See also Ex. 18; the key, and therefore the chord, at the semicadence
is the same as that of the above example (simply major instead of
minor).
Also Ex. 23, No. 4; the semicadence chord is the dominant harmony of
E-flat major; it is skillfully disguised. Ex. 25, dominant harmony of
A major. Ex. 26, last four measures; the semicadence is made upon the
dominant of C minor.
In the following:
the semicadence in the fourth measure is made with the dominant harmony
of C major (the tones g-b-d-f); it is so disguised as to remove all
signs of interruption; but the chord prevails throughout the measure,
and (as may be seen by reference to the original, op. 68, No. 3) the
next measure--the fifth--exactly corresponds to the first; this
indicates another beginning, and proves our ending.
But though the dominant is thus generally employed at the semicadence,
it is by no means the only available chord. It must be remembered that
every cadence which does not fulfil the definite conditions of the
perfect cadence, is a semicadence. Examine each of the following, and
determine why the point of repose is each time a semicadence:--Ex. 1;
Ex. 9, No. 3; Ex. 14, No. 2, fourth measure; Ex. 14, No. 3, fourth
measure; Ex. 19; Ex. 22, Nos. 3 and 4; Ex. 23, No. 2, fourth measure.
The distinction between the two species of cadence becomes most subtle
when the tonic harmony is chosen for the semicadence, but with some
other part of the chord than the keynote as uppermost (or lowermost)
tone. This might appear to lighten the perfect cadence too
immaterially to exercise so radical an influence upon the value
(weight) of the interruption. The keynote, however, is so decisive
and final in its harmonic and melodic effect--everywhere in music--that
its absence more or less completely cancels the terminating quality of
the cadence-chord; in other words, the force of a tonic cadence depends
upon the weight and prominence of the keynote.
The first, second, and third of these cadences is made upon the tonic
harmony, on the accent of each successive fourth measure. But they are
only semicadences, as the melody (uppermost part) rests upon the
Third of the chord, c, instead of the keynote; this substitution of
c for a-flat is sufficient to frustrate the perfect cadence and
diminish it to a transient interruption. The final cadence is perfect,
however, because there the uppermost tone is the keynote. See also
Ex. 21; and Ex. 17, No. 2, fourth measure (semicadence, with a
instead of f as principal tone in upper part, and disguised by the
continuation of rhythmic movement to the end of the cadence-measure).
In Ex. 17, No. 1, the cadence is made with the tonic harmony of G
minor, but with the Third (b-flat) at the top.