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Music Information Retrieval
Classification Of Monophonic Midi-Tunes By
Looking At Their Interval Distribution (COMMID)
Eugen Staab
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Introduction
Music Information Retrieval for
Midi
Transformation possible
Audio
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Motivation

• What is the essence of a text?
• As we have seen for text retrieval By some
  techniques the sequence of terms is ignored but
  they get good results.
• What is the essence of a melody?
• Tempo But can vary in different interpretations
• Dynamics As the tempo not necessarily linked to
  the melody
• Rhythm Determined by the length of the notes
• Tonality Important, but how to represent
  it? Intervals are independent of transposition

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Feature Vectors For Midi-Tunes

• Main Question
• How to represent a monophonic ( for one voice)
  Midi-Tune appropriately, i.e. how to transform it
  into a feature Vector?
• Idea 1 Take the distribution of the
  intervals 25 values for one vector
• 12 intervals up
• 12 intervals down
• The prim interval (identity)
• Idea 2 Take the distribution of the
  interval-transitions
• 25² 625 entries in one vector (All
  combinations of two intervals from above)

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Idea 1 Simple Intervals

• Tests on 2 Collections
• ca. 8000 finnish folk songs,
• ca. 2000 tunes of western music
• Using NMF to create classification vectors
• Problem with intervals Prim(1) is dominanting
  other intervals Treat it as stopword? Doesnt
  help The same problem arises then again
  for the next most frequent intervals.
• Reason Every tune has a similar distribution of
  simple intervals
• Does it change if we look at two consecutive
  intervals?

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Idea 2 Interval Transitions
Same phenomenon Transitions involving the Prim
are dominating the other transitions
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Idea 1 Advancements
New idea Look at the intervals between the notes
of the melodie and its last note
Results
? Looks promising But No recognisable
structures in classifications for second
collection
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Conclusion
Looking at the distribution of the intervals of a
melody seemingly doesnt tell us enough about it
to classify it reasonably
? Maybe a longer sequence of the intervals and/or
the rhythm have to be taken into account as well
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End of presentation.Thanks for your attention!