Key (music)

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Inmusic theory,thekeyof a piece is the group of pitches, orscale,that forms the basis of amusical compositionin Westernclassical music,art music,andpop music.

Tonality (from "Tonic" ) or key: Music which uses the notes of a particular scale is said to be "in the key of" that scale or in the tonality of that scale.

A particular key features atonicnoteand its correspondingchords,also called atonicortonic chord,which provides a subjective sense of arrival and rest, and also has a unique relationship to the other pitches of the same key, their corresponding chords, and pitches and chords outside the key.Notes and chords other than the tonic in a piece create varying degrees of tension,resolvedwhen the tonic note or chord returns.

The key may be in themajor or minormode, though musicians assume major when this is not specified; for example "This piece is in C" implies that the key of the piece is C major.Popular songsand classical music from thecommon practice periodare usually in one key. Longer pieces in the classical repertoire may have sections incontrasting keys.Key changes within a section or movement are known asmodulation.

Overview

Methods that establish the key for a particular piece can be complicated to explain and vary over music history.However, the chords most often used in a piece in a particular key are those that contain the notes in the correspondingscale,and conventionalprogressionsof these chords, particularlycadences,orient the listener around the tonic.

Thekey signatureis not always a reliable guide to the key of a written piece. It does not discriminate between a major key and itsrelativeminor; the piece maymodulateto a different key; if the modulation is brief, it may not involve a change of key signature, being indicated instead withaccidentals.Occasionally, a piece in amodesuch asMixolydianorDorianis written with a major or minor key signature appropriate to the tonic, and accidentals throughout the piece.

Pieces in modes not corresponding to major or minor keys may sometimes be referred to as being in the key of the tonic. A piece using some other type ofharmony,resolving e.g. to A, might be described as "in A" to indicate that A is thetonal centerof the piece.

An instrument "in a key", is an unrelated usage that means the pitches considered "natural" for that instrument. For example, moderntrumpetsare usually in the key of B♭,since the notes produced without using the valves correspond to theharmonic serieswhose fundamental pitch is B♭.(Such instruments are calledtransposingwhen their written notes differ fromconcert pitch.)

Akey relationshipis the relationship between keys, measured bycommon toneand nearness on thecircle of fifths.Seeclosely related key.

Keys and tonality

Perfect authentic cadence (V-I [here inV⁷-I form] with roots in the bass and tonic in the highest voice of the final chord):ii-V⁷-I progressionin C

The key usually identifies thetonicnote and/or chord: the note and/ormajororminortriadthat represents the final point of rest for a piece, or the focal point of a section. Though the key of a piece may be named in the title (e.g., Symphony in C major), or inferred from thekey signature,the establishment of key is brought about viafunctional harmony,a sequence of chords leading to one or morecadences,and/or melodic motion (such as movement from the leading-tone to the tonic). For example, the key of G includes the following pitches: G, A, B, C, D, E, and F♯;and its corresponding tonic chord is G—B—D. Most often at the beginning and end of traditional pieces during the common practice period, the tonic, sometimes with its corresponding tonic chord, begins and ends a piece in a designated key. A key may be major or minor. Music can be described as being in theDorian mode,orPhrygian,etc., and is thus usually thought of as in a specificmoderather than a key. Languages other than English may use otherkey naming systems.

People sometimes confuse key withscale.Ascaleis an ordered set of notes typically used in a key, while thekeyis the "center of gravity" established by particularchord progressions.

Cadences are particularly important in the establishment of key. Even cadences that do not include the tonic note or triad, such ashalf cadencesanddeceptive cadences,serve to establish key because those chord sequences imply a uniquediatonic context.

Short pieces may stay in a single key throughout. A typical pattern for a simplesongmight be as follows: aphraseends with a cadence on the tonic, a second phrase ends with a half cadence, then a final, longer, phrase ends with an authentic cadence on the tonic.

More elaborate pieces may establish the main key, thenmodulateto another key, or a series of keys, then back to the original key. In the Baroque it was common to repeat an entire phrase of music, called aritornello,in each key once it was established. In Classicalsonata form,the second key was typically marked with a contrastingtheme.Another key may be treated as a temporary tonic, calledtonicization.

Incommon practice periodcompositions, and most of the Western popular music of the 20th century, pieces always begin and end in the same key, even if (as in someRomantic-eramusic) the key is deliberately left ambiguous at first. Somearrangementsof popular songs, however, modulate sometime during the song (often in a repeat of the finalchorus) and thus end in a different key. This is an example ofmodulation.

Inrockandpopular musicsome pieces change back and forth, or modulate, between two keys. Examples of this includeFleetwood Mac's "Dreams"andThe Rolling Stones' "Under My Thumb"."This phenomenon occurs when a feature that allows multiple interpretations of key (usually a diatonic set as pitch source) is accompanied by other, more precise evidence in support of each possible interpretation (such as the use of one note as therootof the initiating harmony and persistent use of another note as pitch of melodic resolution and root of the final harmony of each phrase). "

Instruments in a key

Certainmusical instrumentsplay in a certain key, or have their music written in a certain key. Instruments that do not play in the key of C are known astransposing instruments.The most common kind ofclarinet,for example, is said to play in the key of B♭.This means that a scale written in C major insheet musicactually sounds as a B♭major scale when played on the B-flat clarinet—that is, notes sound awhole tonelower than written. Likewise, thehorn,normally in the key of F, sounds notes aperfect fifthlower than written.

Similarly, some instruments are "built" in a certain key. For example, abrass instrumentbuilt in B♭plays afundamentalnote of B♭,and can play notes in theharmonic seriesstarting on B♭without using valves, fingerholes, or slides to alter the length of the vibrating column of air. An instrument built in a certain key often, but not always, uses music written in the same key (seetrombonefor an exception). However, some instruments, such as the diatonicharmonicaand theharp,are in fact designed to play in only one key at a time:accidentalsare difficult or impossible to play.

The highland bagpipes are built in B♭major, though the music is written in D major with implied accidentals.

In Western musical composition, the key of a piece has important ramifications for its composition:

• As noted earlier, certain instruments are designed for a certain key, as playing in that key can be physically easier or harder. Thus the choice of key can be an important one when composing for an orchestra, as one must take these elements into consideration.
• In the life of the professional clarinetist, for example, it is common to carry two instruments tuned a semitone apart (B♭and A) to cope with the needs of composers:Mozart's well-knownclarinet concertois in A major. To play it on a B♭instrument is difficult, and to rewrite all the orchestral parts to B♭major would be an enormous effort. Even so, it is not unheard of for a piece published in B♭to include notes a semitone (or more) below the range of the common B♭clarinet. The piece must then be played on a more exotic instrument, or transposed by hand (or at sight) for the slightly larger A clarinet. There are clarinets with an extended range, with a longer bore and additional keys.
• Besides this though, thetimbreof almost any instrument is not exactly the same for all notes played on that instrument. For this reason a piece that might be in the key of C might sound or "feel" somewhat different (besides being in a different pitch) to a listener if it is transposed to the key of A.
• In addition, since many composers often utilized the piano while composing, the key chosen can possibly have an effect over the composing. This is because the physical fingering is different for each key, which may lend itself to choosing to play and thus eventually write certain notes or chord progressions compared to others, or this may be done on purpose to make the fingering more efficient if the final piece is intended for piano.
• In music that does not useequal temperament,chords played in different keys are qualitatively different.

Key coloration

Key colorationis the difference between theintervalsof different keys in a single non-equal tempered tuning, and the overall sound and "feel" of the key created by the tuning of its intervals.

Historical irregularmusical temperamentsusually have the narrowestfifthsbetween thediatonicnotes ( "naturals" ) producing purerthirds,and wider fifths among the chromatic notes ( "sharps and flats" ). Each key then has a slightly differentintonation,hence different keys have distinct characters. Such "key coloration" was an essential part of much eighteenth- and nineteenth-century music and was described in treatises of the period.

For example, in tunings with awolf fifth,the key on the lowest note of the fifth sounds dramatically different from other keys (and is often avoided). InPythagorean tuningon C (C, E+, G: 4, 5, 6), the major triad on C is just while the major triad on E♯+++ (F♮) is noticeably out of tune (E♯+++, A+, C:4+1⁄8,5, 6) due to E♯+++ (521.44 cents) being aPythagorean comma(23.46 cents) larger sharp compared to F♮.

Music usingequal temperamentlacks key coloration because all keys have the same pattern of intonation, differing only in pitch.

Further reading

• Innig, Renate (1970).System der Funktionsbezeichnung in den Harmonielehren seitHugo Riemann.Düsseldorf: Gesellschaft zur Förderung der systematischen Musikwissenschaft.
• Rahn, John(1980).Basic Atonal Theory.New York: Longman; London and Toronto: Prentice Hall International.ISBN0-02-873160-3.Reprinted 1987, New York: Schirmer Books; London: Collier Macmillan.
• Steblin, Rita(1983).A History of Key Characteristics in the 18th and Early 19th Centuries.UMI Research Press, Ann Arbor.

External links

• Christian Schubart's "Affective Key Characteristic"
• Characteristics of Musical Keys– from various sources.
• Key Color
• Historical Tuning – Restoring Key Coloration to Period Music