Diatonic and chromatic
Diatonic and chromatic are terms in music
theory that are most often used to character-
ise scales, and are also applied to intervals,
chords, notes, musical styles, and kinds of
harmony. They are very often used as a pair,
especially when applied to contrasting fea-
tures of the common practice music of the
period 1600–1900.[1]
These terms may mean different things in
different contexts. Very often, diatonic
refers to musical elements derived from the
modes and transpositions of the "white note
scale" C–D–E–F–G–A–B (see details below).[2]
In some usages it includes all forms of hep-
tatonic scale that are in common use in
Western music (the major, and all forms of
the minor).[3] Chromatic refers to structures
derived from the chromatic scale, which con-
sists of all semitones.
History
Tetrachord genera of the four-string lyre,
from The History of the Arts and Sciences of
the Antients, Charles Rollin (1768). The text
gives a typically fanciful account of the term
chromatic.
Greek genera
In ancient Greece there were three standard
tunings (known by the Latin word genus,
plural genera)[4] of the four-string lyre – an
instrument that was accepted as a model for
other instrumental and vocal music. These
three tunings were called diatonic,[5] chro-
matic,[6] and enharmonic,[7] and the se-
quences of four notes that they produced
were called tetrachords ("four strings").[8] A
diatonic tetrachord comprised, in descending
order, two whole tones and a semitone, such
as A G F E (roughly). In the chromatic tetra-
chord the second string of the lyre was
lowered from G to G♭, so that the two lower
intervals in the tetrachord were semitones,
making the pitches A G♭ F E. In the enhar-
monic tetrachord the tuning had two quarter
tone intervals at the bottom: A F F♭ E (where
F♭ is F♮ lowered by a quarter tone). For all
three tetrachords, only
the middle two
strings varied in their pitch.[9]
Medieval coloration
The term cromatico (Italian) was occasion-
ally used in the Medieval and Renaissance
periods to re