An approach to classifying four-part music in multidimensional space - Emerging Trends in Image Processing, Computer Vision, and Pattern Recognition - page 22

4 Collecting Piece Statistics
After the XML has been parsed, FPC moves immediately to the next step: Collecting Piece
Statistics.

4.1 Metrics
Statistics are collected for each piece via 19 Boolean tests on each chord or chord change. These
Boolean tests produce the following metrics (Diagram 111):

DIAGRAM 111

ThirdAppearsOnlyOnceInSAT The percent of chords whose third appears only once in the upper three
voices. In classical writing, it is preferable that the third appear just once in the upper three voices.
ThirdNotDoubledInUnison The percent of chords whose third is not doubled in unison. Doubling the
third in unison is usually avoided unless necessary.
FifthDoubledInSecondInversion The percent of second-inversion chords whose fifth is doubled. Clas-
sically, it is preferable that the fifth be doubled in second inversion.
CrossOver The percent of chords not containing overlapping parts. It is preferable that voices do not
cross over. Doubling in unison is fine.
SETOctave The percent of chords whose soprano and alto pitches as well as alto and tenor pitches differ
by not more than an octave. This is a fairly strict rule in classical, four-part writing. The distance between the bass
and tenor does not matter and may be great.
SevenChordContainsDiminishedFifth The percent of vii° chords with a fifth. While the fifths of other
chords are often omitted, the diminished fifth of a vii° chord adds an important quality and its presence is a strict
requirement in classical writing.
NoParallelFifths

The percent of chord changes free of parallel fifths. This is a strict rule of classical writ-

ing.

NoParallelOctaves The percent of chord changes free of parallel octaves. This is also a strict rule.
NoDirectFifthsInOuterVoices The percent of chord changes free of direct fifths in the outer voices. This
is a fairly important rule in classical writing.
NoDirectOctavesInOuterVoices

The percent of chord changes free of direct octaves in the outer voices.

This also is a fairly important rule.
LeapingParts The percent of chord changes involving a part jumping by a major seventh, a minor sev-
enth, or the tri-tone. Jumping the tri-tone in a nonmelodic voice part is never acceptable in classical writing, but
from time to time, leaps by major and minor sevenths and even tri-tones are permissible if in the soprano.
StepwiseMovements The percent of chord changes in which at least one voice moves by no more than
a major second. While this is not a formal rule of classical writing per se , good writing generally has very few chord
changes in which all four parts leap.