Phrase rhythm is, in its most basic sense, the rhythm articulated by a series of phrases. Just as a series of notes in a melody articulates a rhythm, a durational pattern, so too a series of phrases articulates a rhythm.
Rhythm can give rise to meter, and the kind of meter appropriate for the long durations of phrase is called hypermeter.
William Rothstein, in the second chapter of Phrase Rhythm in Tonal Music, does us a service by clearly distinguishing phrases from hypermeasures. He points out two particular effects that result from the fact that phrases and (hyper)measures do not always begin simultaneously.
upbeat pattern: The phrase begins before a downbeat.
afterbeat pattern: The downbeat occurs before the phrase begins.
Phrase Structure and Metrical Structure
Phrase rhythm is concerned with interactions between phrase structure and metrical structure, particularly at the levels of phrase and hypermeter. Let’s examine phrase structure and metrical structure more closely. Each involves a hierarchy of levels:
A phrase is a unit of music that exhibits tonal motion that results in a cadence at its end. Periods group phrases together and end with a conclusive cadence, usually a PAC. Phrases may subdivide into smaller units, called subphrases.
Metrical units are a series of approximately equal spans of time, each initiated by an expectation, on the part of a listener, that musical events (such as notes within a melody) are likely to begin at these points in time.
Beats are the metrical units we are likely to represent by tapping with our hands or our feet. Measures combine beats in sets of either two or three. Meter, which can be defined as regular alternation between strong and weak beats, is the result of a combination of two levels of metrical units. Duple meter is the combination of two beats per measure; triple meter is the combination of 3 beats per measure.
Measures combine to form hypermeasures. Duple hypermeter is the combination of 2 measures per hypermeasure. Triple hypermeter is the combination of 3 measures per hypermeasure. “Hyperbeats,” then, are measures.
If you find the beats of your conducting pattern aligning with bar lines in the score, you are experiencing hypermeter. You move more slowly to conduct the hypermeter than to conduct the meter.
Playing with Boundaries between Phrases and Hypermeasures
There are two main ways of eliminating “dead air” between phrases:
(1) phrase overlap, in which the end of one phrase is also the beginning of the next, and
(2) link (or “lead-in”), in which a subordinate idea connects the end of one phrase to the beginning of the next.
Hypermeter admits some irregularities. This is despite the fact that meter is defined as the regular alternation of strong and weak beats. To help sell this seemingly contradictory idea, Rothstein points out instances, such as cadenzas, in which the meter (not just the hypermeter) is “put on hold,” so to speak.
There are two main kinds of disruption to the normal succession of hyperbeats and hypermeasures:
(1) metrical reinterpretation, in which a weak hyperbeat is reinterpreted as a strong hyperbeat, and
(2) suspended hypermeter, or elongated (hyper)beats, in which the arrival of the next hyperbeat is delayed.
Note that both phrase overlap and metrical reinterpretation have to do with a contraction or omission of musical material. Something new begins early. That is why they appear side-by-side in the table above. Furthermore, metrical reinterpretation occurs, it seems, only in conjunction with a phrase overlap. Phrase overlap on the other hand, can occur alone, without metrical reinterpretation.
Also note that both links and suspended hypermeter have to do with the addition of extra material in between either phrases or hypermeasures. Links occur between phrases. Hypermeter is usually suspended between hypermeasures, not within them. An elongated upbeat occurs when a phrase begins with a long pickup and the downbeat of the next hypermeasure is delayed. Suspended hypermeter also can occur at the end of a hypermeasure, as sometimes occurs while the last chord of a phrase is held out for a long span of time.
All these techniques of subtracting or adding time between phrases and hypermeasures are pertinent to phrase rhythm because they can affect the pace at which a series of phrases occurs.