14.5: Periods
- Page ID
- 258567
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Next Level Form
Our smallest level of musical form was the motif. Those are developed into phrases that end in some type of cadence. The next level of form organizes those phrases into what we call a period.
A period is a pair of two phrases, each ending in a cadence. The first phrase ends in a weaker cadence, and the second phrase ends in a stronger cadence.
Parallel Periods
Periods are further described by the relationship of their melodic material. When each phrase starts with similar material, we call it a parallel period. Our first phrase in the piece can be labeled with a lowercase "a." If we have an exact repeat of that same material, we will label it with another "a." If the material starts the same, but ends differently, we will label it with a' (pronounced "a-prime").
Consider the traditional melody for "Mary Had a Little Lamb." This melody is in two phrases, each beginning the same, but ending differently. We will call the first phrase "a" and the second phrase "a'."
For a closer look, the identical material has been circled in red.
Contrasting Periods
When each phrase starts with different material, we call it a contrasting period. If the first phrase of the piece is labeled with a lowercase "a," the next phrase, being different, is labeled with a lowercase "b." This continues with each consequent phrase. If the material is repeated from an earlier phrase, the phrase will be labeled with the same letter. If the material is new and has not yet been heard, it is labeled with a new letter.
Consider the first eight measures of the folk song, "Golden Boat Song." As we look to determine our phrases, we are looking both at melodic material and at the harmonic accompaniment. Measures one and two are focused around our tonic chord, E-flat major, which is made up of: E-flat, G, and B-flat. Tones that do not fall into that chord can be considered embellishing tones. Our first harmonic change is in measure three with the implication of the dominant seventh chord: B-flat, D (if it was present), F, and A-flat. We can determine that this phrase is four measures long and ends in a perfect authentic cadence (PAC), however it is weakened since the third of the dominant chord was missing. We will call this the "a" phrase.
We then look to the melodic material in our next four measures. Rhythmically, it is similar. It could be argued that the melodic material is entirely different since the intervals are different than the first phrase. The chord changes in the last two measures are a strong root-position dominant chord that resolves to root-position tonic and again has do in the soprano voice. This is also a perfect authentic cadence (PAC), and a stronger one than the previous cadence. We will call this the "b" phrase.
This would be a contrasting period and we could draw a diagram indicating the phrases and cadences.
Attribution:
"Golden Boat Song" from The Child's Own Music Book, by Albert E.Wier, 1918. Assigned Jan. 5, 1920 to World Syndicate Company, Inc. Assigned Nov. 3, 1922 to Mumil Publishing Co, Inc. "Golden Boat Song" is used by permission of Traditional Music Library