Introduction to Harmony, Cadences, and Phrase Endings

Harmony is the study of how chords are built and how they relate to one another over time. In tonal music, each chord belongs to one of three broad functional categories: tonic (T), predominant (PD), and dominant (D). Tonic chords (I and vi) provide stability and a sense of arrival. Predominant chords (IV and ii) move away from the tonic and prepare the dominant. Dominant chords (V and viiº) create tension that demands resolution back to the tonic. A typical phrase follows the arc T–PD–D–T, a pattern called the phrase model.

A cadence is the harmonic gesture that closes a phrase — essentially the musical equivalent of punctuation. The four main cadence types are: the perfect authentic cadence (PAC), the imperfect authentic cadence (IAC), the half cadence (HC), and the deceptive cadence (DC). A PAC ends with V moving to I in root position, with 1̂ (do) in the soprano — the strongest possible close. An IAC also uses V–I, but either the chords are inverted, the soprano ends on 3̂ or 5̂ rather than 1̂, or both, creating a weaker sense of closure.

A half cadence ends on V without resolving to I, leaving the phrase open — like a question waiting for an answer. The chords preceding the dominant can vary widely, but the defining feature is that V falls on the final strong beat of the phrase. A deceptive cadence (or evaded cadence) begins like an authentic cadence but substitutes vi (or another non-tonic chord) for the expected I, surprising the ear and propelling the music forward. Recognizing these patterns is essential to hearing and analyzing tonal music at the phrase level.