Chord (music)

In music, harmony is the concept of combining different sounds in order to create new, distinct musical ideas. Theories of harmony seek to describe or explain the effects created by distinct pitches or tones coinciding with one another; harmonic objects such as chords, textures and tonalities are identified, defined, and categorized in the development of these theories. Harmony is broadly understood to involve both a "vertical" dimension (frequency-space) and a "horizontal" dimension (time-space), and often overlaps with related musical concepts such as melody, timbre, and form.

A particular emphasis on harmony is one of the core concepts underlying the theory and practice of Western music. The study of harmony involves the juxtaposition of individual pitches to create chords, and in turn the juxtaposition of chords to create larger chord progressions. The principles of connection that govern these structures have been the subject of centuries worth of theoretical work and vernacular practice alike.

Musical improvisation (also known as musical extemporization) is the creative activity of immediate ("in the moment") musical composition, which combines performance with communication of emotions and instrumental technique as well as spontaneous response to other musicians. Sometimes musical ideas in improvisation are spontaneous, but may be based on chord changes in classical music and many other kinds of music. One definition is a "performance given extempore without planning or preparation". Another definition is to "play or sing (music) extemporaneously, by inventing variations on a melody or creating new melodies, rhythms and harmonies". Encyclopædia Britannica defines it as "the extemporaneous composition or free performance of a musical passage, usually in a manner conforming to certain stylistic norms but unfettered by the prescriptive features of a specific musical text." Improvisation is often done within (or based on) a pre-existing harmonic framework or chord progression. Improvisation is a major part of some types of 20th-century music, such as blues, rock music, jazz, and jazz fusion, in which instrumental performers improvise solos, melody lines and accompaniment parts.

Throughout the eras of the Western art music tradition, including the Medieval, Renaissance, Baroque, Classical, and Romantic periods, improvisation was a valued skill. J. S. Bach, Handel, Mozart, Beethoven, Chopin, Liszt, and many other famous composers and musicians were known especially for their improvisational skills. Improvisation might have played an important role in the monophonic period. The earliest treatises on polyphony, such as the Musica enchiriadis (ninth century), indicate that added parts were improvised for centuries before the first notated examples. However, it was only in the fifteenth century that theorists began making a hard distinction between improvised and written music.

Sheet music is a handwritten or printed form of musical notation that uses musical symbols to indicate the pitches, rhythms, or chords of a song or instrumental musical piece. Like its analogs – printed books or pamphlets in English, Arabic, or other languages – the medium of sheet music typically is paper (or, in earlier centuries, papyrus or parchment). However, access to musical notation since the 1980s has included the presentation of scores on computer screens and the development of scorewriter computer programs that can notate a song or piece electronically, and, in some cases, "play back" the notated music using a synthesizer or virtual instruments.

The use of the term sheet is intended to differentiate written or printed forms of music from sound recordings (on vinyl record, cassette, CD), radio or TV broadcasts or recorded live performances, which may capture film or video footage of the performance as well as the audio component. In everyday use, sheet music (or simply music) can refer to the print publication of commercial sheet music in conjunction with the release of a new film, TV show, record album, or other unique or popular event which involves music. The first printed sheet music made with a printing press was made in 1473.

In music, a homorhythm or homometer is a texture having a "similarity of rhythm in all parts" or "very similar rhythm" as would be used in simple hymn or chorale settings. Homorhythm is a condition of homophony. All voices sing the same rhythm. This texture results in a homophonic texture, which is a blocked chordal texture. Homorhythmic texture delivers lyrics with clarity and emphasis. Texture in which parts have different rhythms is heterorythmic or heterometric.

The term is used for compositions in which all the voice-parts move simultaneously in the same rhythm, forming a succession of chords. It may also be called chordal style, familiar style, vertical harmony, note-against-note style, isometric, and homophonic. Isometric may used to refer to music in which each vocal part has the same number of syllables, with isorythmic being used to refer to music in which each voice has the same rhythm.

A lead sheet or fake sheet is a form of musical notation that specifies the essential elements of a popular song: the melody, lyrics and harmony. The melody is written in modern Western music notation, the lyric is written as text below the staff and the harmony is specified with chord symbols above the staff.

The lead sheet does not describe the chord voicings, voice leading, bass line or other aspects of the accompaniment. These are specified later by an arranger or improvised by the performers, and are considered aspects of the arrangement or performance of a song, rather than a part of the song itself. "Lead" refers to a song's lead part, the most important melody line or voice.

In a musical composition, a chord progression or harmonic progression (informally chord changes, used as a plural, or simply changes) is a succession of chords. Chord progressions are the foundation of harmony in Western musical tradition from the common practice era of classical music to the 21st century. Chord progressions are the foundation of popular music styles (e.g., pop music, rock music), traditional music, as well as genres such as blues and jazz. In these genres, chord progressions are the defining feature on which melody and rhythm are built.

In tonal music, chord progressions have the function of either establishing or otherwise contradicting a tonality, the technical name for what is commonly understood as the "key" of a song or piece. Chord progressions, such as the extremely common chord progression I-V-vi-IV, are usually expressed by Roman numerals in classical music theory. In many styles of popular and traditional music, chord progressions are expressed using the name and "quality" of the chords. For example, the previously mentioned chord progression, in the key of E♭ major, would be written as E♭ major–B♭ major–C minor–A♭ major in a fake book or lead sheet. In the first chord, E♭ major, the "E♭" indicates that the chord is built on the root note "E♭" and the word "major" indicates that a major chord is built on this "E♭" note.

Jazz is a music genre that originated in the African-American communities of New Orleans, Louisiana, in the late 19th and early 20th centuries. Its roots are in blues, ragtime, European harmony, African rhythmic rituals, spirituals, hymns, marches, vaudeville song, and dance music. Since the 1920s Jazz Age, it has been recognized as a major form of musical expression in traditional and popular music. Jazz is characterized by swing and blue notes, complex chords, call and response vocals, polyrhythms and improvisation.

As jazz spread around the world, it drew on national, regional, and local musical cultures, which gave rise to different styles. New Orleans jazz began in the early 1910s, combining earlier brass band marches, French quadrilles, biguine, ragtime and blues with collective polyphonic improvisation. However, jazz did not begin as a single musical tradition in New Orleans or elsewhere. In the 1930s, arranged dance-oriented swing big bands, Kansas City jazz (a hard-swinging, bluesy, improvisational style), and gypsy jazz (a style that emphasized musette waltzes) were the prominent styles. Bebop emerged in the 1940s, shifting jazz from danceable popular music toward a more challenging "musician's music" which was played at faster tempos and used more chord-based improvisation. Cool jazz developed near the end of the 1940s, introducing calmer, smoother sounds and long, linear melodic lines.

A chord chart (or chart) is a form of musical notation that describes the basic harmonic and rhythmic information for a song or tune. It is the most common form of notation used by professional session musicians playing jazz or popular music. It is intended primarily for a rhythm section (usually consisting of piano, guitar, drums and bass). In these genres the musicians are expected to be able to improvise the individual notes used for the chords (the "voicing") and the appropriate ornamentation, counter melody or bassline.

In some chord charts, the harmony is given as a series of chord symbols above a traditional musical staff. The rhythmic information can be very specific and written using a form of traditional notation, sometimes called rhythmic notation, or it can be completely unspecified using slash notation, allowing the musician to fill the bar with chords or fills any way they see fit (called comping). In Nashville notation the key is left unspecified on the chart by substituting numbers for chord names. This facilitates on-the-spot key changes to songs. Chord charts may also include explicit parts written in modern music notation (such as a musical riff that the song is dependent on for character), lyrics or lyric fragments, and various other information to help the musician compose and play their part.

Accompaniment is the musical part which provides the rhythmic and/or harmonic support for the melody or main themes of a song or instrumental piece. There are many different styles and types of accompaniment in different genres and styles of music. In homophonic music, the main accompaniment approach used in popular music, a clear vocal melody is supported by subordinate chords. In popular music and traditional music, the accompaniment parts typically provide the "beat" for the music and outline the chord progression of the song or instrumental piece.

The accompaniment for a vocal melody or instrumental solo can be played by a single musician playing an instrument such as piano, pipe organ, or guitar. While any instrument can in theory be used as an accompaniment instrument, keyboard and guitar-family instruments tend to be used if there is only a single instrument, as these instruments can play chords and basslines simultaneously (chords and a bassline are easier to play simultaneously on keyboard instruments, but a fingerpicking guitarist can play chords and a bassline simultaneously on guitar). A solo singer can accompany themself by playing guitar or piano while they sing, and in some rare cases, a solo singer can even accompany themself just using their voice and body (e.g., Bobby McFerrin).

In music, monophony is the simplest of musical textures, consisting of a melody (or "tune"), typically sung by a single singer or played by a single instrument player (e.g., a flute player) without accompanying harmony or chords. Many folk songs and traditional songs are monophonic. A melody is also considered to be monophonic if a group of singers (e.g., a choir) sings the same melody together at the unison (exactly the same pitch) or with the same melody notes duplicated at the octave (such as when men and women sing together). If an entire melody is played by two or more instruments or sung by a choir with a fixed interval, such as a perfect fifth, it is also said to be monophony (or "monophonic"). The musical texture of a song or musical piece is determined by assessing whether varying components are used, such as an accompaniment part or polyphonic melody lines (two or more independent lines).

In the Early Middle Ages, the earliest Christian songs, called plainchant (a well-known example is Gregorian chant), were monophonic. Even into the twenty-first century, songwriters still often write songs that intersperse sections using monophony, heterophony (two singers or instrumentalists doing varied versions of the same melody together), polyphony (two or more singers or instrumentalists playing independent melodic lines at the same time), homophony (a melody accompanied by chords), or monody (a single melodic line with instrumental accompaniment) elements throughout the melody to create different atmospheres and styles. Monophony may not have underlying rhythmic textures, and must consist of only a single melodic line.

Tonality is the arrangement of pitches and/or chords of a musical work in a hierarchy of perceived relations, stabilities, attractions, and directionality.

In this hierarchy, the single pitch or the root of a triad with the greatest stability in a melody or in its harmony is called the tonic. In this context "stability" approximately means that a pitch occurs frequently in a melody – and usually is the final note – or that the pitch often appears in the harmony, even when it is not the pitch used in the melody.

In Western musical theory, a cadence (from Latin cadentia 'a falling') is the end of a phrase in which the melody or harmony creates a sense of full or partial resolution, especially in music of the 16th century onwards. A harmonic cadence is a progression of two or more chords that concludes a phrase, section, or piece of music. A rhythmic cadence is a characteristic rhythmic pattern that indicates the end of a phrase. A cadence can be labeled "weak" or "strong" depending on the impression of finality it gives.

While cadences are usually classified by specific chord or melodic progressions, the use of such progressions does not necessarily constitute a cadence—there must be a sense of closure, as at the end of a phrase. Harmonic rhythm plays an important part in determining where a cadence occurs. The word "cadence" sometimes slightly shifts its meaning depending on the context; for example, it can be used to refer to the last few notes of a particular phrase, or to just the final chord of that phrase, or to types of chord progressions that are suitable for phrase endings in general.

A barbershop quartet is a group of four singers who sing music in the barbershop style, characterized by four-part harmony without instrumental accompaniment (a cappella). The four voices are: the lead, the vocal part which typically carries the melody; a bass, the part which provides the bass line to the melody; a tenor, the part which harmonizes above the lead; and a baritone, the part that frequently completes the chord. The baritone normally sings just below the lead singer, sometimes just above as the harmony requires. Barbershop music is typified by close harmony—the upper three voices generally remain within one octave of each other.

While the traditional barbershop quartet included only male singers, contemporary quartets can include any gender combination. All-female barbershop quartets were often called beauty shop quartets, a term that has fallen out of favor. The voice parts for women's and mixed barbershop groups use the same names as those for male groups since the roles perform similar functions in the quartet although the vocal ranges may be different.

In musical notation, stems are the "thin, vertical lines that are directly connected to the [note] head." Stems may point up or down. Different-pointing stems indicate the voice for polyphonic music written on the same staff. Within one voice, the stems usually point down for notes on the middle line or higher, and up for those below. If the stem points up from a notehead, the stem originates from the right-hand side of the note, but if it points down, it originates from the left. If there are multiple notes beamed together, the stem's direction is defined by the average of the lowest and highest notes in the beam. There is an exception to this rule: if a chord contains a second, the stem runs between the two notes with the higher being placed on the right of the stem and the lower on the left. If the chord contains an odd numbered cluster of notes a second apart (such as C, D, E), the outer two will be on the correct side of the stem, while the middle note will be on the wrong side.

The length of a stem should be that of an octave on the staff, going to either an octave higher or lower than the notehead, depending on which way the stem is pointing. If a note head is on a ledger line more than an octave away from the middle line of a staff, the stem will be elongated to touch the middle line. In any polyphonic music in which two parts are written on the same staff, stems are typically shortened to keep the music visually centered upon the staff.

In music theory, an interval is a difference in pitch between two sounds. An interval may be described as horizontal, linear, or melodic if it refers to successively sounding tones, such as two adjacent pitches in a melody, and vertical or harmonic if it pertains to simultaneously sounding tones, such as in a chord.

In Western music, intervals are most commonly differencing between notes of a diatonic scale. Intervals between successive notes of a scale are also known as scale steps. The smallest of these intervals is a semitone. Intervals smaller than a semitone are called microtones. They can be formed using the notes of various kinds of non-diatonic scales. Some of the very smallest ones are called commas, and describe small discrepancies, observed in some tuning systems, between enharmonically equivalent notes such as C♯ and D♭. Intervals can be arbitrarily small, and even imperceptible to the human ear.

Musical technique is the ability of instrumental and vocal musicians to exert optimal control of their instruments or vocal cords in order to produce the precise musical effects they desire. Improving one's technique generally entails practicing exercises that improve one's muscular sensitivity and agility. Technique is independent of musicality. Compositional technique is the ability and knowledge composers use to create music, and may be distinguished from instrumental or performance technique, which in classical music is used to realize compositions, but may also be used in musical improvisation. Extended techniques are distinguished from more simple and more common techniques. Musical technique may also be distinguished from music theory, in that performance is a practical matter, but study of music theory is often used to understand better and to improve techniques. Techniques such as intonation or timbre, articulation, and musical phrasing are nearly universal to all instruments.

To improve their technique, musicians often practice ear training. For example, musical intervals, and fundamental patterns and of notes such as the natural, minor, major, and chromatic scales, minor and major triads, dominant and diminished sevenths, formula patterns and arpeggios. For example, triads and sevenths teach how to play chords with accuracy and speed. Scales teach how to move quickly and gracefully from one note to another (usually by step). Arpeggios teach how to play broken chords over larger intervals. Many of these components of music are found in difficult compositions, for example, a large tuple chromatic scale is a very common element to Classical and Romantic era compositions as part of the end of a phrase.