Metric Well-formedness & Preference Rules

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In their Grand Theory of Tonal Music (GTTM), Lerdahl and Jackendoff lay out a set of metric well-formedness rules (MWFRs) and metric preference rules (MPRs). These are guidelines for establishing a metrical framework and for assigning metrical accents.

The MWFRs apply for a given point in a piece.

MWFR 1: Every attack point must be associated with a beat at the lowest metrical level

MWFR 2: Every beat at a given level must exist as a beat at all smaller levels present

MWFR 3: Strong beats are spaced either two or three beats apart at every metrical level

MWFR 4: The tactus and larger metrical levels must consist of equally-spaced beats that span the entire piece. At levels below the tactus, the weak beats must be spaced equally between strong beats.

The MPRs are based on parallelism, a preference for an early strong beat, pitch events, stress, length, hesitation, metrically stable bass, cadences, and suspensions, minimized time-span reduction, and a preference for binary meters at all levels.

LERDAHL Fred, and Ray JACKENDOFF. 1983. A Generative Theory of Tonal Music. Cambridge: MIT Press, 1–35. Dodson, Alan. “Performance and hypermetric transformation: An extension of the Lerdahl-Jackendoff theory,” Music Theory Online 8/1 (2002): external link: