In music and music theory, a chord
(from the middle English cord, short
for accord) is three or more different
notes or pitches sounding simultaneously,
or nearly simultaneously, over a period
of time. For example, if you simultaneously
play any three (or more) keys of a piano,
you have just played a chord. Likewise,
if you simultaneously play three or
more strings of a guitar,
you have just played a chord on the
guitar. Every
chord is given a specific name, based
on the notes that constitute the chord
and the distances, or intervals, between
them.
Originally, a chord simply meant the
sounding together of different tones,
the resultant of these tones. Broadly,
any combination of three or more
notes is a chord,
although during the common practice
period in western music and most popular
music some combinations were given more
prominence than others. Thus in common
usage a chord is only those groups of
three notes which are tonal or have
diatonic functionality. Chords being
directly perceived units, sonorities
of two pitches are often interpreted
as fragments of three- or four-note
chords.
A chord is then also only the harmonic
function of the group of three notes,
and it is unnecessary to have all three
notes form a simultaneity. Less than
three notes may and often do function,
in context, as a simultaneity of all
notes of chord. One example is a power
chord, another is a broken chord or
arpeggio, where each note in a chord
is sounded one after the other. One
of the most familiar broken chord figures
is Alberti bass. See accompaniment.
Although, as Jean-Jacques Nattiez (1990,
p.218) explains, "we can encounter
'pure chords' in a musical work,"
such as in the following example from
the "Promenade" of Modest
Mussorgsky's Pictures at an Exhibition:
But "often, we must go from a
textual given to a more abstract representation
of the chords being used," as in
the following example where the chords
on the second stave are abstracted from
the actual notes written on the first:
"For a sound configuration to
be recognized as a chord, it must have
a certain duration." Goldman (1965,
p.26) elaborates: "the sense of
harmonic relation, change, or effect
depends on speed (or tempo) as well
as on the relative duration of single
notes or triadic units. Both absolute
time (measurable length and speed) and
relative time (proportion and division)
must at all times be taken into account
in harmonic thinking or analysis."
Music is said to be chord-based when
the melody is determined by the chords
and not by melodic concerns such as
modal frames.
|