Music is composed of
aural phenomena; "music theory" considers how those phenomena apply in music. Music theory considers melody, rhythm, counterpoint, harmony, form, tonal systems, scales, tuning, intervals, consonance, dissonance, durational proportions, the acoustics of pitch systems, composition, performance, orchestration, ornamentation, improvisation, electronic sound production, etc.
Pitch Pitch is the lowness or highness of a
tone, for example the difference between
middle C and a higher C. The frequency of the sound waves producing a pitch can be measured precisely, but the perception of pitch is more complex because single notes from natural sources are usually a complex mix of many frequencies. Accordingly, theorists often describe pitch as a subjective sensation rather than an objective measurement of sound. Specific frequencies are often assigned letter names. Today most orchestras assign
concert A (the A above
middle C on the piano) to the frequency of 440 Hz. This assignment is somewhat arbitrary; for example, in 1859 France, the same A was tuned to 435 Hz. Such differences can have a noticeable effect on the timbre of instruments and other phenomena. Thus, in
historically informed performance of older music, tuning is often set to match the tuning used in the period when it was written. Additionally, many cultures do not attempt to standardize pitch, often considering that it should be allowed to vary depending on genre, style, mood, etc. The difference in pitch between two notes is called an
interval. The most basic interval is the
unison, which is simply two notes of the same pitch. The
octave interval is two pitches that are either double or half the frequency of one another. The unique characteristics of octaves gave rise to the concept of
pitch class: pitches of the same letter name that occur in different octaves may be grouped into a single "class" by ignoring the difference in octave. For example, a high C and a low C are members of the same pitch class—the class that contains all C's.
Musical tuning systems, or temperaments, determine the precise size of intervals. Tuning systems vary widely within and between world cultures. In
Western culture, there have long been several competing tuning systems, all with different qualities. Internationally, the system known as
equal temperament is most commonly used today because it is considered the most satisfactory compromise that allows instruments of fixed tuning (e.g. the piano) to sound acceptably in tune in all keys.
Scales and modes Notes can be arranged in a variety of
scales and
modes. Western music theory generally divides the octave into a series of twelve pitches, called a
chromatic scale, within which the interval between adjacent tones is called a
semitone, or half step. Selecting tones from this set of 12 and arranging them in patterns of semitones and whole tones creates other scales. The most commonly encountered scales are the seven-toned
major, the
harmonic minor, the
melodic minor, and the
natural minor. Other examples of scales are the
octatonic scale and the
pentatonic or five-tone scale, which is common in
folk music and
blues. Non-Western cultures often use scales that do not correspond with an equally divided twelve-tone division of the octave. For example, classical
Ottoman,
Persian,
Indian and
Arabic musical systems often make use of multiples of quarter tones (half the size of a semitone, as the name indicates), for instance in 'neutral' seconds (three quarter tones) or 'neutral' thirds (seven quarter tones)—they do not normally use the quarter tone itself as a direct interval. In traditional Western notation, the scale used for a composition is usually indicated by a
key signature at the beginning to designate the pitches that make up that scale. As the music progresses, the pitches used may change and introduce a different scale. Music can be
transposed from one scale to another for various purposes, often to accommodate the range of a vocalist. Such transposition raises or lowers the overall pitch range, but preserves the interval relationships of the original scale. For example, transposition from the key of C major to D major raises all pitches of the scale of C major equally by a
whole tone. Since the interval relationships remain unchanged, transposition may be unnoticed by a listener, however other qualities may change noticeably because transposition changes the relationship of the overall pitch
range compared to the range of the instruments or voices that perform the music. This often affects the music's overall sound, as well as having technical implications for the performers. The interrelationship of the keys most commonly used in Western tonal music is conveniently shown by the
circle of fifths. Unique key signatures are also sometimes devised for a particular composition. During the Baroque period, emotional associations with specific keys, known as the
doctrine of the affections, were an important topic in music theory, but the unique tonal colorings of keys that gave rise to that doctrine were largely erased with the adoption of equal temperament. However, many musicians continue to feel that certain keys are more appropriate to certain emotions than others.
Indian classical music theory continues to strongly associate keys with emotional states, times of day, and other extra-musical concepts and notably, does not employ equal temperament.
Consonance and dissonance Consonance and dissonance are subjective qualities of the sonority of intervals that vary widely in different cultures and over the ages. Consonance (or concord) is a feeling that an interval or chord is stable, harmonious, or complete. While dissonance (or discord) is a feeling that the interval or chords are incomplete, clashing, or unresolved. In western music theory, perfect fourths, fifths, and octaves and all major and minor thirds and sixths are considered consonant, while other intervals are considered dissonant to a greater or lesser degree. Context and many other aspects can affect apparent dissonance and consonance. For example, in a Debussy prelude, a major second may sound stable and consonant, while the same interval may sound dissonant in a Bach fugue. In the
Common practice era, the perfect fourth is considered dissonant when not supported by a lower third or fifth. Since the early 20th century,
Arnold Schoenberg's concept of "emancipated" dissonance, in which traditionally dissonant intervals can be treated as "higher", more remote consonances, has become more widely accepted.
Rhythm s: beat level shown in middle with division levels above and multiple levels below Rhythm is produced by the sequential arrangement of sounds and silences in time.
Meter measures music in regular pulse groupings, called
measures or bars. The
time signature or meter signature specifies how many beats are in a measure, and which value of written note is counted or felt as a single beat. Through increased stress, or variations in duration or articulation, particular tones may be accented. There are conventions in most musical traditions for regular and hierarchical accentuation of beats to reinforce a given meter.
Syncopated rhythms contradict those conventions by accenting unexpected parts of the beat. Playing simultaneous rhythms in more than one time signature is called
polyrhythm. In recent years, rhythm and meter have become an important area of research among music scholars. The most highly cited of these recent scholars are
Maury Yeston,
Fred Lerdahl and
Ray Jackendoff,
Jonathan Kramer, and Justin London.
Melody " melody A
melody is a group of sounds in succession, a tune, or an arrangement. Melody is often a prominent aspect of music, and so its construction and qualities are a primary interest of music theory. The basic elements of melody are pitch, duration, rhythm, and tempo. The tones of a melody are usually drawn from pitch systems such as
scales or
modes. Melody may consist, to increasing degree, of the figure, motive, semi-phrase, antecedent and consequent phrase, and period or sentence. The period may be considered the complete melody, however some examples combine two periods, or use other combinations of constituents to create larger form melodies.
Chord . in
just intonation in
Equal temperament in
1/4-comma meantone in
Young temperament in
Pythagorean tuning A chord, in music, is any
harmonic set of three or more
notes that is heard as if sounding
simultaneously. These need not actually be played together:
arpeggios and broken chords may, for many practical and theoretical purposes, constitute chords. Chords and
sequences of chords are frequently used in modern Western, West African, and Oceanian music, whereas they are absent from the music of many other parts of the world. The most frequently encountered chords are
triads, so called because they consist of three distinct notes: further notes may be added to give
seventh chords,
extended chords, or
added tone chords. The most
common chords are the
major and
minor triads and then the
augmented and
diminished triads. The descriptions
major,
minor,
augmented, and
diminished are sometimes referred to collectively as chordal
quality. Chords are also commonly classed by their
root note—so, for instance, the chord
C major may be described as a triad of major quality built on the note
C. Chords may also be classified by
inversion, the order in which the notes are stacked. A series of chords is called a
chord progression. Although any chord may in principle be followed by any other chord, certain patterns of chords have been accepted as establishing
key in
common-practice harmony. To describe this, chords are numbered, using
Roman numerals (upward from the key-note), per their
diatonic function. Common ways of
notating or representing chords in western music other than conventional
staff notation include
Roman numerals,
figured bass (much used in the
Baroque era),
chord letters (sometimes used in modern
musicology), and various systems of
chord charts typically found in the
lead sheets used in
popular music to lay out the sequence of chords so that the musician may play accompaniment chords or improvise a solo.
Harmony s, such as this US Navy group, sing 4-part pieces, made up of a melody line (normally the second-highest voice, called the "lead") and 3 harmony parts. In music, harmony is the use of simultaneous
pitches (
tones,
notes), or
chords. The study of harmony involves chords and their construction and
chord progressions and the principles of connection that govern them. Harmony is often said to refer to the "vertical" aspect of music, as distinguished from
melodic line, or the "horizontal" aspect.
Counterpoint, which refers to the interweaving of melodic lines, and
polyphony, which refers to the relationship of separate independent voices, is thus sometimes distinguished from harmony. In
popular and
jazz harmony, chords are named by their
root plus various terms and characters indicating their qualities. For example, a
lead sheet may indicate chords such as C major, D minor, and G dominant seventh. In many types of music, notably Baroque, Romantic, modern, and jazz, chords are often augmented with "tensions". A tension is an additional chord member that creates a relatively
dissonant interval in relation to the bass. It is part of a chord, but is not one of the chord tones (1 3 5 7). Typically, in the classical
common practice period a dissonant chord (chord with tension) "resolves" to a consonant chord.
Harmonization usually sounds pleasant to the ear when there is a balance between the consonant and dissonant sounds. In simple words, that occurs when there is a balance between "tense" and "relaxed" moments.
Timbre of the first second of an E9 chord played on a Fender Stratocaster guitar with noiseless pickups. Below is the E9 chord audio: Timbre, sometimes called "color", or "tone color", is the principal phenomenon that allows us to distinguish one instrument from another when both play at the same pitch and volume, a quality of a voice or instrument often described in terms like bright, dull, shrill, etc. It is of considerable interest in music theory, especially because it is one component of music that has as yet, no standardized nomenclature. It has been called "... the psychoacoustician's multidimensional waste-basket category for everything that cannot be labeled pitch or loudness," but can be accurately described and analyzed by
Fourier analysis and other methods because it results from the combination of all sound
frequencies, attack and release envelopes, and other qualities that a tone comprises.
Timbre is principally determined by two things: (1) the relative balance of
overtones produced by a given instrument due its construction (e.g. shape, material), and (2) the
envelope of the sound (including changes in the overtone structure over time). Timbre varies widely between different instruments, voices, and to lesser degree, between instruments of the same type due to variations in their construction, and significantly, the performer's technique. The timbre of most instruments can be changed by employing different techniques while playing. For example, the timbre of a trumpet changes when a mute is inserted into the bell, the player changes their embouchure, or volume. A voice can change its timbre by the way the performer manipulates their vocal apparatus, (e.g. the shape of the vocal cavity or mouth). Musical notation frequently specifies alteration in timbre by changes in sounding technique, volume, accent, and other means. These are indicated variously by symbolic and verbal instruction. For example, the word
dolce (sweetly) indicates a non-specific, but commonly understood soft and "sweet" timbre.
Sul tasto instructs a string player to bow near or over the fingerboard to produce a less brilliant sound.
Cuivre instructs a brass player to produce a forced and stridently brassy sound. Accent symbols like
marcato (^) and dynamic indications (
pp) can also indicate changes in timbre.
Dynamics In music, "
dynamics" normally refers to variations of intensity or volume, as may be measured by physicists and audio engineers in
decibels or
phons. In music notation, however, dynamics are not treated as absolute values, but as relative ones. Because they are usually measured subjectively, there are factors besides amplitude that affect the performance or perception of intensity, such as timbre, vibrato, and articulation. The conventional indications of dynamics are abbreviations for Italian words like
forte (
f) for loud and
piano (
p) for soft. These two basic notations are modified by indications including
mezzo piano (
mp) for moderately soft (literally "half soft") and
mezzo forte (
mf) for moderately loud,
sforzando or
sforzato (
sfz) for a surging or "pushed" attack, or
fortepiano (
fp) for a loud attack with a sudden decrease to a soft level. The full span of these markings usually range from a nearly inaudible
pianissississimo (
pppp) to a loud-as-possible
fortissississimo (
ffff). Greater extremes of
pppppp and
fffff and nuances such as
p+ or
più piano are sometimes found. Other systems of indicating volume are also used in both notation and analysis: dB (decibels), numerical scales, colored or different sized notes, words in languages other than Italian, and symbols such as those for progressively increasing volume (
crescendo) or decreasing volume (
diminuendo or
decrescendo), often called "
hairpins" when indicated with diverging or converging lines as shown in the graphic above.
Articulation ,
staccatissimo,
marcato,
accent,
tenuto.
Articulation is the way the performer sounds notes. For example,
staccato is the shortening of duration compared to the written note value, and
legato means a series of notes played in a smoothly joined sequence with no separation. Articulation is often described rather than quantified, therefore there is room to interpret how to execute precisely each articulation. For example,
staccato is often referred to as "separated" or "detached" rather than having a defined or numbered amount by which to reduce the notated duration. Violin players can use a variety of techniques to perform different qualities of
staccato. The manner in which a performer decides to execute a given articulation is usually based on the context of the piece or phrase, but many articulation symbols and verbal instructions depend on the instrument and musical period (e.g. viol, wind; classical, baroque; etc.). There is a set of articulations that most instruments and voices perform in common. They are—from long to short:
legato (smooth, connected);
tenuto (played to full notated duration);
accented (with emphasis);
marcato (strong emphasis and clipped short, marked);
staccato (separated, detached);
staccatissimo (very separated, extreme staccato). Many of these can be combined to create certain "in-between" articulations. For example,
portato is the combination of
tenuto and
staccato. Some instruments have unique methods by which to produce sounds, such as
spiccato for bowed strings, where the bow bounces off the string.
Texture 's "
Washington Post March", mm. 1–7 features
octave doubling and a homorhythmic texture In music, texture is how the
melodic,
rhythmic, and
harmonic materials are combined in a
composition, thus determining the overall quality of the sound in a piece. Texture is often described in regard to the density, or thickness, and
range, or width, between lowest and highest pitches, in relative terms as well as more specifically distinguished according to the number of voices, or parts, and the relationship between these voices. For example, a thick texture contains many "layers" of instruments. One of these layers could be a string section, or another brass. The thickness also is affected by the number and the richness of the instruments playing the piece. The thickness varies from light to thick. A lightly textured piece will have light, sparse scoring. A thickly or heavily textured piece will be scored for many instruments. A piece's texture may be affected by the number and character of parts playing at once, the
timbre of the instruments or voices playing these parts and the harmony,
tempo, and rhythms used. The types categorized by number and relationship of parts are analyzed and determined through the labeling of primary textural elements: primary melody, secondary melody, parallel supporting melody, static support, harmonic support, rhythmic support, and harmonic and rhythmic support. Common types included
monophonic texture (a single melodic voice, such as a piece for solo soprano or solo flute), biphonic texture (two melodic voices, such as a duo for bassoon and flute in which the bassoon plays a drone note and the flute plays the melody),
polyphonic texture and
homophonic texture (chords accompanying a
melody).
Form or structure .
Encyclopaedia Britannica calls a "canon" both a compositional technique and a musical form. The term musical form (or musical architecture) refers to the overall structure or plan of a piece of music, and it describes the layout of a composition as divided into sections. In the tenth edition of
The Oxford Companion to Music,
Percy Scholes defines musical form as "a series of strategies designed to find a successful mean between the opposite extremes of unrelieved repetition and unrelieved alteration." According to
Richard Middleton, musical form is "the shape or structure of the work". He describes it through difference: the distance moved from a
repeat; the latter being the smallest difference. Difference is quantitative and qualitative:
how far, and
of what type, different. In many cases, form depends on statement and
restatement, unity and variety, and
contrast and connection.
Expression Musical expression is the art of playing or singing music with emotional communication. The elements of music that comprise expression include dynamic indications, such as forte or piano,
phrasing, differing qualities of timbre and articulation, color, intensity, energy and excitement. All of these devices can be incorporated by the performer. A performer aims to elicit responses of sympathetic feeling in the audience, and to excite, calm or otherwise sway the audience's physical and emotional responses. Musical expression is sometimes thought to be produced by a combination of other parameters, and sometimes described as a transcendent quality that is more than the sum of measurable quantities such as pitch or duration. Expression on instruments can be closely related to the role of the breath in singing, and the voice's natural ability to express feelings, sentiment and deep emotions. Whether these can somehow be categorized is perhaps the realm of academics, who view expression as an element of musical performance that embodies a consistently recognizable
emotion, ideally causing a
sympathetic emotional response in its listeners. The emotional content of musical expression is distinct from the emotional content of specific sounds (e.g., a startlingly-loud 'bang') and of learned associations (e.g., a
national anthem), but can rarely be completely separated from its context. The components of musical expression continue to be the subject of extensive and unresolved dispute.
Notation Musical notation is the written or symbolized representation of music. This is most often achieved by the use of commonly understood graphic symbols and written verbal instructions and their abbreviations. There are many systems of music notation from different cultures and different ages. Traditional Western notation evolved during the Middle Ages and remains an area of experimentation and innovation. In the 2000s, computer
file formats have become important as well. Spoken language and
hand signs are also used to symbolically represent music, primarily in teaching. In standard Western music notation, tones are represented graphically by symbols (notes) placed on a
staff or staves, the vertical axis corresponding to pitch and the horizontal axis corresponding to time. Note head shapes, stems, flags, ties and dots are used to indicate duration. Additional symbols indicate keys, dynamics, accents, rests, etc. Verbal instructions from the conductor are often used to indicate tempo, technique, and other aspects. In Western music, a range of different music notation systems are used. In Western Classical music, conductors use printed scores that show all of the instruments' parts and orchestra members read parts with their musical lines written out. In popular styles of music, much less of the music may be notated. A rock band may go into a recording session with just a handwritten
chord chart indicating the song's
chord progression using chord names (e.g., C major, D minor, G7, etc.). All of the chord voicings, rhythms and accompaniment figures are improvised by the band members. ==As academic discipline==