Phrase:A term adopted from linguistic syntax and used for short musical units of various lengths; a phrase is generally regarded as longer than a Motif but shorter than a Period.
from The Grove Dictionary of Music and Musicians
Sounds complicated. A phrase can be said to be a musical unit or musical idea. Usually phrases come in pairs or groups. Pairs of phrases are called Periods,
Question – Answer
In music, a period represents what can be termed a question and answer unit. The first phrase of a period asks a question or leaves a musical idea unfinished, which the second phrase answers or finishes.
The technical term for the phrases in a period are Antecedent and Consequent. The Antecedent phrase asks the questions while the Consequent answers.
To make a phrase sound unfinished or wanting more, composers will often make use of the various types of cadences. A half cadence, as explained before, leaves the listener waiting for a completion. Thus it makes a great ending for an antecedent phrase. Other times a phrase my modulate or toncize another key area providing the listener with a sense that the piece has gone somewhere, only to return by the end of the consequent phrase. In short, a antecedent phrase ends open or wants completion. A consequent phrase ends closed or completed.
Even an imperfect authentic cadence will sound less complete than a perfect authentic cadence, provide composers even more of a means for exploring endings of antecedent phrases. A phrase that ends on I6 will sound more unfinished and than a phrase ending on tonic in root position. The possibilities are literally endless, but the best way to tell is by using your ear. Play a piece and stop at a phrase ending. Could the piece end there? If no, chances are it needs a consequent phrase to complete the idea.
In the cases of groups greater than two phrases there are many possibilities. These groups of more than two phrases are called Phrase Groups. A composer could choose to end two phrases open followed by one phrase closed, forming a three-phrase group. Another possibility would be to end the first phrase open, followed by another phrase closed, then completing the group with a repeat of the second phrase or a short repeat of the cadence to reinforce the closure of the phrase group.
Back to Sor’s B-minor Etude
We can examine phrase structure by returning to Sor’s B minor Etude. Measure 1-8 constitute the first complete phrase. At measure 8 sort ends on the dominant providing a half cadence that leaves the ear waiting for a resolution. That resolution comes as Sor beings the next phrase at measure 9 with a tonic, b minor. He then closes the phrase with a perfect authentic cadence in measure 15 (V7) and 16 (i). The first phrase in measures 1-8 is the antecedent followed by the consequent in measure 9-16. Together the two phrases form a Period or complete idea which also closes the A section of the etude.
From a musicality stand point, phrases should have an ebb and flow or rise and fall to them. Generally a musical idea has an almost arch. A phrase with lead into it’s climax then taper off to it’s finish. Sometimes that climax may come half way through, but in the Sor study, it comes at the very beginning of measure 8 as he makes use of the E# to lead into the dominant. As a performer this means a bit of a crescendo into that E – E# motion, followed by a decrescendo through the dominant chord in measure 16. It’s also possible to speed up a bit into measure 15, followed by a relaxing of the tempo in measure 16.
For the second phrase, the climax is right around 13 with the introduction of the E in the bass voice on beat three. The next two measures are a cadential dominant chord followed by tonic in measure 16. Again, crescendo into measure 14, followed by a decrescendo into measure 16. Here too it’s possible to speed up into the climax and then relax away from it.
Important Note: the above represents my analysis of the piece. Everyone’s opinion will differ when it comes to musical interpretation. I’d love to hear some disagreement or other opinions in the comments! Please, leave a note in the comments with your interpretation.