Transcript Document
Signatures and Earmarks: Computer Recognition of Patterns in Music By David Cope http://arts.ucsc.edu/faculty/cope/ Presented by Andy Lee Overview •Two types of patterns for analyzing music •Signatures •Earmarks •Other than just notes, harmony, rhythm… Signatures •Definition •A term for motives common to two or motive works of a given composer •What is this for? •Can tell us what period of music history a work comes from. •Can tell the probable composer of that work Signatures •Description •Typically 2 to 5 beats in length •Often composites of melodic, harmonic, and rhythmic elements •Usually occur between 4 and 10 times in any given work •Variation often include transposition, diatonic interval alteration, rhythmic refiguring, and registral and voice shifting Signature - example By Mozart (a) (b) Piano Sonata K.280(1774) mvt. 1, mm. 107-8 Piano Concerto K.453(1784), mvt.1, mm. 162-3 The melody has been truncated with a more active version of the accompaniment. (from 1774 to 1784, 10 years) Signatures •Stylistic Analysis •Observing a signature change and develop over time can provide valuable insights into how a given style matures and how one can differentiate by ear the various periods in the life of a composer •Tend to articulate the ideas and materials composers have in common, and what make each composer unique. Signature - placement Five examples of a Viennese signature. Versions of a signature found in Mozart’s Piano Sonata K.284, mvt. 2: (a) m.16; (b) m.30; © m.46; (d) m.69; (e) m.92; •A Premature tonic bass note under a dominant chord, or a late-sounding dominant over a tonic pedal point. •Experienced listeners can tell the misplaced signature Signature - similarity (a) 1 -4 -3 -2 -1 1 -3 -4 2 (b) •Using intervals shows more similarity in the two patterns than using pitches. •To the ear, these are easily identifiable as simple variations of the same pattern Signature - EMI • EMI (Experiments in Musical Intelligence) • A tunable program to let real signature pass • 3 basic rules for pattern matching 1. Allowing one step difference 2. Allowing different direction (2 -2) 3. Allowing extra note Earmarks •Definition •Patterns in music indicate attributes besides style •Identified most easily by ear and tend to mark specific structural location in a work •Can tell us what movement of a work we are hearing •Can foreshadow particularly important structural events •Can contribute to our expectations of when a movement or work should climax or end Earmarks •As Gestural Information •Variations of earmarks point out their gestural nature •Can typically be described in general terms •Trill followed by a scale •An upward second followed by a downward third •Location: appear at particular points in compositions •Finding earmark helps pinpoint important nexus point Earmark - example An earmark from the first movements of Mozart’s Piano Concertos: K.238, mm. 86-7 Earmarks •As an aid to Structural Perception •Misplaced earmarks can cause a disruption in an educated listener’s perception of the apparent musical structure. •Earmarks which do not precede anticipated sections, occur out of sequence, or are ill-timed can cause rifts in the antecedent-consequent motion so important to musical structure.