I had mentioned with the Introduction of the Baroque Era not only its harmonic development from the Renaissance, but also its rhythmic drive. One of the characteristic devices that developed and became common by the end of the Baroque is the rhythmic “hemiola.”
Whereas chant melodies simply followed the declamation of the text, the Baroque era organized the rhythm into repeating patterns. Hemiola was a way to stretch out those patterns, essentially defying the natural metric design, creating interest and a sense of drama. Rhythm is the heartbeat of music. When we are surprised we speak of our heart skipping a beat. That is somewhat the traumatic, thickening effect of hemiola.
Hemiola played upon the established metric order, such as repeated groupings per measure of twos (2/4), threes (3/4 or 3/8), or fors (4/4), and then gave you something you were not expecting by superimposing a different grouping within the same meter so as to suggest a different meter than the dominant one. Not only did it provide some variety, but was often used to emphasize the words or to build some tension or excitement before a major cadence, much as good theater.
Handel oftentimes uses the device to emphasize a text. Typically, such devices are used toward the end of phrases to thicken the texture, stretch out the rhythmic organization as it created harmonic tension before finally resolving into the tonic chord (or “home”). Messiah is full of them. Sometimes the hemiola is suggested by the natural rhythm of the speech patterns of the lyrics. Sometimes, as Handel uses it, the hemiola is obvious because all of the parts are organized such as to reinforce each other. Sometimes, however, it is not so obvious and remains hidden within the fabric of the dominant meter. When Handel uses it in Messiah, it is used to support the text. Here are a few examples:
And the Glory of the Lord – “shall be redeemed” is introduced in 3/4 time, but upon its final utterance within that phrase section, it is augmented to half notes, themselves being organized in a group of four before it leaps back into 3/4:
As I perceive the musical setting of the text from “I know that my Redeemer Liveth,” “he shall stand at the latter ‘day upon the earth’,” that section. The aria is in 3/4 time. The above text is introduced in that same meter, but the penultimate presentation of it within that part is augmented from quarter note beats or pulses to half note pulses organized in 4/2, stretching out that same text. To further heighten the drama, the first violin part remains in 3/4 time as the bass follows and reinforces the declamation of the lyrics:
A wonderful example of hemiola is provided by Mozart in his Divertimento in E-Flat. One cannot miss the hemiola because although the pieces written in 34 time, it opens with the hemiola and then re-Kersey each time that theme returns:
In His Fourth Symphony, Third Movement, Tchaikovsky plays the coquettish, constantly shifting pattern of a meter of 5/4, within which he groups beats in 2+3, 3+2, 2+3, 3+2. The fact that one expects a group of to be followed by a group of two, then a group of three with a group 3, builds an expectation which unifies the piece. It feels almost like a waltz, but not quite. In the middle of that section, there is a contrasting section melodically, harmonically, and rhythmically in which the pace seems to rest for a moment, yet by the repetition of the same pattern and grouping of 2+3, 2+3, 2+3 becomes restless by insistence, preparing the listener to the return of that alternating pattern and melody which we were first introduced.
Bernstein’s” America” from West Side Story plays with a similar concept except that it alternates measures of 6/8 and 3/4 patterns throughout the entire piece, using it as a unifying, yet driving and dynamically ecstatic device from beginning to end.
In “Take Five” Dave Brubeck also uses a 5/4 meter, but, throughout, maintains the grouping of 3+2 which gives it a jazzy relentless drive.
To explore concepts of rhythmic structure on a larger scale within a musical composition, I recommend The Rhythmic Structure of Music by Cooper and Meyer