Chord (music)

A guitar player performing a C chord with G bass.

A chord, in music, is any harmonic set of pitches consisting of multiple notes (also called "pitches") that are heard as if sounding simultaneously.[1][2] For many practical and theoretical purposes, arpeggios and broken chords (in which the notes of the chord are sounded one after the other, rather than simultaneously), or sequences of chord tones, may also be considered as chords.

Chords and sequences of chords are frequently used in modern West African[3] and Oceanic music,[4] Western classical music, and Western popular music; yet, they are absent from the music of many other parts of the world.[5]

In tonal Western classical music (music with a tonic key or "home key"), the most frequently encountered chords are triads, so called because they consist of three distinct notes: the root note, and intervals of a third and a fifth above the root note. Chords with more than three notes include added tone chords, extended chords and tone clusters, which are used in contemporary classical music, jazz and other genres.

A series of chords is called a chord progression.[6] One example of a widely used chord progression in Western traditional music and blues is the 12 bar blues progression. Although any chord may in principle be followed by any other chord, certain patterns of chords are more common in Western music, and some patterns have been accepted as establishing the key (tonic note) in common-practice harmony—notably the resolution of a dominant chord to a tonic chord. To describe this, Western music theory has developed the practice of numbering chords using Roman numerals[7] to represent the number of diatonic steps up from the tonic note of the scale.

Common ways of notating or representing chords[8] in Western music (other than conventional staff notation) include Roman numerals, the Nashville Number System, figured bass, macro symbols (sometimes used in modern musicology), and chord charts.

Definition

The English word chord derives from Middle English cord, a shortening of accord[9] in the original sense of agreement and later, harmonious sound.[10] A sequence of chords is known as a chord progression or harmonic progression. These are frequently used in Western music.[5] A chord progression "aims for a definite goal" of establishing (or contradicting) a tonality founded on a key, root or tonic chord.[7] The study of harmony involves chords and chord progressions and the principles of connection that govern them.[11]



    { #(set-global-staff-size 18)
      \new PianoStaff <<
        \new Staff <<
            \new voice \relative c'' {
                \set Score.tempoHideNote = ##t \tempo 4 = 112
                \clef treble \key bes \major 
				\time 5/4
					<bes, d g>4 <a c f> <bes d bes'> \stemDown <c a'> \stemNeutral <f a d>
				\time 6/4
					\stemDown <c a'> \stemNeutral <f bes d> <d g bes> <e g c> <g, c g'> <a c f>
				}
			\new Voice \relative c'' {
				\time 5/4
					s2. \stemUp c8^( f d4)
				\time 6/4
					\stemUp c8^( f d4) s1
                }
            >>
        \new Staff <<
			\clef bass \key bes \major 
            \relative c {
				\time 5/4
					<g g'>4 <a f'> <g g'> <f f'> <d d'>
                \time 6/4
					<f f'> <bes bes'> <g g'> <c, c'> <e e'> <f f'>
				}
            >>
    >> }
Mussorgsky's Pictures at an Exhibition "Promenade", is a piece showing an explicit chord progression. (Nattiez 1990, p. 218)

Ottó Károlyi[12] writes that, "Two or more notes sounded simultaneously are known as a chord," though, since instances of any given note in different octaves may be taken as the same note, it is more precise for the purposes of analysis to speak of distinct pitch classes. Furthermore, as three notes are needed to define any common chord, three is often taken as the minimum number of notes that form a definite chord.[13] Hence, Andrew Surmani, for example, (2004, p. 72) states, "When three or more notes are sounded together, the combination is called a chord." George T. Jones (1994, p. 43) agrees: "Two tones sounding together are usually termed an interval, while three or more tones are called a chord." According to Monath (1984, p. 37); "A chord is a combination of three or more tones sounded simultaneously," and the distances between the tones are called intervals. However, sonorities of two pitches, or even single-note melodies, are commonly heard as implying chords.[14] A simple example of two notes being interpreted as a chord is when the root and third are played but the fifth is omitted. In the key of C major, if the music comes to rest on the two notes G and B, most listeners will hear this as a G major chord.



{
#(set-global-staff-size 16)
     \override Score.TimeSignature #'stencil = ##f
      <<
        \new Staff <<
            \relative c' {
                \clef treble \time 4/4 \key e \major
                \tuplet 3/2 { cis8 e a } \tuplet 3/2 { cis e fis } \tuplet 3/2 {gis dis b } \tuplet 3/2 { gis dis b } \tuplet 3/2 { a cis fis } \tuplet 3/2 { a cis dis } \tuplet 3/2 { e b gis } \tuplet 3/2 { e b gis }
                }
            >>
        \new Staff <<
           \relative c' {
                \clef treble \time 4/4 \key e \major
                \tempo "Andantino con moto"
                <cis e a>2 <b dis gis> <a cis fis> <gis b e>
                }
            >>
    >> }
Claude Debussy's Première arabesque. The chords on the lower stave are constructed from the notes in the actual piece, shown in the upper stave.

Since a chord may be understood as such even when all its notes are not simultaneously audible, there has been some academic discussion regarding the point at which a group of notes may be called a chord. Jean-Jacques Nattiez (1990, p. 218) explains that, "We can encounter 'pure chords' in a musical work," such as in 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 Claude Debussy's Première arabesque.