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Presentation Automatic Pitch Spelling From Numbers to Sharps and Flats Emilios Cambouropoulos Xiaodan Wu Feb.12 2003 About the author Emilios Cambouropoulos completed his PhD thesis on Music and Artificial Intelligence at the University of Edinburgh. Till February 1999, he worked as a research associate at King's College London on a musical data-retrieval project: Musical Similarity and Melodic Recognition. Currently, he is working as a research fellow at the Austrian Research Institute for Artificial Intelligence on the project: Artificial Intelligence Models of Musical Expression. Publication we are going to study: •The Local Boundary Detection Model (LBDM) and its Application in the Study of Expressive Timing • From MIDI to Traditional Musical Notation What’s the challenge? An example from the pitch representation in MIDI and its alternative spelling It’s polyphonic No prior knowledge such as Key signature Tonal centers Time signature Voice separation 60 Midi Pitch Dbb | C | B# Alternative spelling The previous works Researcher Algorithm features Common points Cambouropoulos Avoids diminished, augmented and chromatic 1996 intervals Only for monophonic pitch sequences Temperley 1997 Avoids doublesharps and double Spells pitches so that as flats close as possible together on the “line of fifths” Can be applied to polyphonic pitch sequences The pitch spelling algorithm The input to the algorithm is a list of MIDI pitch values The optimization procedure relies on two fundamental principles: Notational Parsimony Interval Optimization Penalty values are introduced. The pitch spelling algorithm continue Distance 1 2 3 Intervals 4P 2M 3m 5P 7m 6M Class A Intervals 4P 2M 3m 5P 7m 6M 4 5 6 7 8 9 10 11 12 3M 6m 2m 7M 4a 5d 1a 1d 4d 5a 2a 7d 3d 6a 3a 6d 2d 7a B C 3M 6m 2m 7M 2a 7d 3d 6a D 4d 5a 4a 5d 1a 1d 3a 6d 2d 7a The pitch spelling algorithm continue Penalty Values: Notational Parsimony ‘normal’ spelling of note enharmonic spelling of note 0 4 Interval Optimization Class A or B Class C ClassD 0 1 3 For each spelled pitch sequence, all the penalty values for every possible intervals are summed. And the sequence with the lowest penalty value is selected. The pitch spelling algorithm continue A shifting overlapping windowing technique is hired to pick up certain sequence for spelling pitches The length of the window could be modified. The Result Experiment 1 Total # of notes Notes with accidentals 40058 10900 Misspelled notes 649 Correct Spelling 94% Experiment 2 Total # of notes Notes with accidentals 40058 10900 Misspelled notes 501 Correct Spelling 95.4% Experiment 3 Total # of notes 40058 Notes with accidentals 10900 Misspelled notes 424 Correct Spelling 96.2% The drawback There is a trade-off for the different pitch interval orderings. The technique to select the length for the window. Voice-leading concerns are not currently considered.
