Introduction to Harmony, Cadences, and Phrase Endings — Open Music Theory

Claims

1. cadences
   Cadences are melodic and harmonic patterns that mark phrase endings and help establish a key. An authentic cadence ends a phrase with V–I; it is perfect when both chords are in root position and the tonic is in the soprano, and imperfect otherwise. A half cadence ends a phrase on V and sounds inconclusive. Perfect authentic cadences are the strongest kind of cadence and half cadences the weakest.

   "One way to create a sense of closure at the end of a phrase is through cadences —melodic and harmonic patterns that create goals, kind of like punctuation marks in literary sentences. They're important not only because they can help you determine phrase endings, but also because they help establish a key. ... Authentic cadences involve the progression V–I. They are perfect when both harmonies are in root position and do is in the soprano over tonic. If either of these conditions is not met, the authentic cadence is imperfect. ... A half cadence (HC) occurs when a phrase ends on V ... PACs are the strongest kind of cadence available to a composer because of the sense of finality they can create, and HCs are the weakest kind of cadence because of their unfinished sound."

   Locator: section: Introduction to Cadences; Cadential Strength and the IAC · Quote language: en
2. function-phrase-model
   Harmonic function groups chords into three categories: tonic (I or i, which sounds stable), predominant (chords that lead away from tonic toward dominant, such as IV and ii), and dominant (V and vii°, which create a sense of urgency to resolve to the tonic). The phrase model describes the typical order of these functions in a phrase: a phrase needs at least tonic and dominant function to have a sense of trajectory, often includes a predominant, and almost always moves from tonic toward dominant rather than the reverse.

   "Harmonic function refers to three categories of chords: Tonic (T) : Chords that sound stable, providing a sense of home or center. In Western classical music, the only chord that belongs to this category is I (in minor: i). Predominant (PD) : Chords that transition away from tonic function toward dominant function. ... Dominant (D) : Chords that provide a sense of urgency to resolve toward the tonic chord: V and vii o (the same in minor). The phrase model refers to the typical order and flow of harmonic functions in a phrase. The principle of the phrase model is that a phrase needs at least tonic function and dominant function harmonies in order to exhibit a sense of trajectory. More often, phrases also include a predominant harmony to heighten the sense of trajectory toward closure. Phrases almost always progress from left to right in the phrase model, not from right to left"

   Locator: section: Introduction to Harmony · Quote language: en