Phrase Rhythm
The rate at which (and the way in which) phrases
(and thus cadences) succeed
one another.
In a way, a composition's phrase rhythm determines the rate at
which (and the way in which) it breathes.
Consider the following Bach chorale setting, which exhibits a very
simple kind of phrase rhythm:
Observations:
- Of the setting's six fermatas, only the last
five signal real cadences -- the fermata in m. 1 is a
caesura.
- The phrase rhythm is regular, since
there is one cadence every two measures.
- Every phrase in this setting ends in the same
way, with a clean break and pause. (Some choral conductors take
fermatas in Bach's chorale settings to mean "breathe here" rather
than "come to a full stop".) This can result in a somewhat
monotonous phrase rhythm unless other musical elements intervene
to add interest: a good performance of this chorale would probably
make mm. 1-4 into a single unit, making more of each successive
fermata -- the first two fermatas shouuld be underplayed so that
the third fermata sounds like a real point of arrival.
Composers often add variety to a piece's phrase
rhythm by using one or more of the techniques of phrase rhythm
development listed below:
Introduction
- A bar or two of accompaniment prior to the start of the phrase
itself (in pop music, a "vamp")
- A few chords that establish the harmonic context and mood
prior to the start of the phrase itself.
Link (lead-in)
A chordal or melodic figure that joins the end of one phrase with
the start of the next. Here is an example of a melodic link:
[Mozart, Adagio to K. 576, mm. 15-17]
Phrase extension
The addition of extra material at the cadence.
Phrase expansion
The interpolation of extra material prior to the cadence of a
phrase. Clearly this is only possible in the consequent phrase of a
period, or during the restatement of a phrase heard previously.
Elision
The last note of one phrase is also the first note of the
next.
Phrase overlap
While one phrase ends in one voice, the next phrase begins in
another voice.