Acoustics & Music Theory
why it sounds like that
Concept

Antecedent consequent — where it appears

A pair of phrases in which the first arrives at a weak ending and the second repeats its material and arrives at a strong one. It is the smallest form in which a return is also a resolution, and the pairing is what makes eight bars feel complete.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

Two ways to fill eight bars, and only one of them accelerates. The period against the sentence, drawn as the lengths of their constituent units against position on a grid of eight bars. The ratio beside each row is the mean unit length in its second half divided by the mean in its first: the period at 1.00, the sentence at 0.67. A ratio below one is an acceleration — the unit shortening as the phrase approaches its arrival — and a ratio of one is a plan whose unit never changes length.

One of these eight-bar phrases accelerates

The sentence and the period both occupy eight bars, both end with a cadence, and both are recognised by ear rather than counted. What separates them is arithmetic. One halves its unit halfway through and the other does not, and the difference comes out as a single ratio — 0.67 against 1.00 — computed from nothing but the lengths of the parts.

form · Phrase Five signals, computed separately, and no total. The five components of closure for 4 chord pairs. The first three are computed from the chords alone; the last two are properties of where the goal lands and how long it is held. There is no total column: the components are not commensurable and the ordering of these cadences depends on which is weighted.

An ending that exists so a bigger one can

Half of the cadences in tonal music are built to fail. A phrase that stopped convincingly at bar four would be a piece four bars long, so the ending at bar four is engineered to arrive and not to settle — and the components it withholds are exactly the ones its partner at bar eight supplies. Closure is nested, and the nesting is what turns two phrases into one thing.

form · Closure

Named alongside it

The objects these essays reach for when they reach for this one.

CadenceExpectationPhraseClosureFragmentationGroupingHalf cadenceHierarchyHypermetreRepetitionSentence

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