Carl Dahlhaus (1990) lists the characteristic schemata of tonal harmony, "typified in the compositional formulas of the 16th and early 17th centuries," as the "complete cadence" (vollständige Kadenz), I-IV-V-I, I-IV-I-V-I, or even I-ii-V-I; the circle of fifths progression: I-IV-vii-iii-vi-ii-V-I, and the "major-minor parallelism", minor: v-i-VII-III = major: iii-vi-V-I or minor: III-VII-i-v = major: I-V-vi-iii.
David Cope (1997) considers key, consonance or relaxation and dissonance or tension, and hierarchical relationships to be the three most basic concepts in tonality. In describing these tenets of tonal music, several known terms are used to refer to various elements of the tonal system.
Music is considered to be tonal if it includes most or all of the following features:
Since the mid-18th century, tonal music has been increasingly composed of a 12-note chromatic scale in a system of equal temperament. Tonal music makes reference to "scales" of notes selected as a series of steps from the chromatic scale. Most of these scales are of 5, 6, or 7 notes with the vast majority of tonal music pitches conforming to one of four specific seven-note scales: major, natural minor, melodic minor, and harmonic minor.
C major scale:
A natural minor scale:
Other scales or modes are often introduced for variety within the context of a major-minor tonal system without disturbing the diatonic nature of the work. The major scale predominates and the melodic minor contains nine pitches (seven with two alterable). The seven basic notes of a scale are notated in the key signature, and whether the piece is in the major or minor key is either stated in the title or implied in the piece (there is a major and minor key for each key signature). While other scales and modes are used in tonal music, particularly after 1890, these two scales are the reference point for most tonal music and its vocabulary.
Other important scales include the other church modes, the blues scale, the whole tone scale used by many Russian composers, pentatonic scale and the chromatic scale. Since none of these are the major or minor diatonic scales, music written exclusively with them is, by the definition above, not tonal.
Tone-centric music composed in other scale systems may be microtonal, and while microtonal music theory may draw from tonal theory, it is generally treated separately in textbooks and other works on music. However, within the tonal system, notes "between" the chromatic system are used in various contexts, including quarter tones and various effects such as portamento or glissando, where the instrumentalist moves between established notes of the diatonic scale. These are usually thought of as being for "colour" rather than harmonic function, and do not disturb the fundamental (diatonic) scale being used.
Chords are built from notes of a diatonic scale, or secondarily on chromatic notes treated as variations or embellishments of the basic scale. The identity of the scale is important in that the scale's steps used as roots determine the system of chord relationships. At any given time one scale degree is heard as the most important (the "tonic"), and the chord built on it, always a major or minor triad, is heard as the most forceful closure.
The degree of a scale is both the pitch (frequency) of that note and that pitch's diatonic function (role), which is why chords are named by scale degree. Thus the notes of a chord do not have to be sounded simultaneously, and one to two notes may function as, or imply, a three (or more) note chord. Thus a chord described as "V" is based on the fifth note of the prevailing tonic scale (V-VII-II). In C Major, that would be a triad based on G, and would be the G Major triad (G-B-D). To describe a chord progression, the Roman numerals of the chords are listed. Thus IV-V-I describes a chord progression of a chord based on the fourth note of a scale, then one based on the fifth note of the scale, and then one on the first note of the scale.
Chords are then further named according to their quality or makeup, determined by the scale notes which lie a third and fifth (two thirds) above the degree a chord is built upon. Capital Roman numerals refer to the major chord, and lower-case Roman numerals refer to the minor chord. Quality is generally not as important as the chord's root.
This means that in the traditional major scale, the ii, iii and vi are minor chords, where as I, IV, V are major. The chord on the seventh note is a diminished triad and is written vii with a degree sign. Numbers attached to a chord indicate additional notes, and one of the most important chords in tonal harmony is the V7 chord, which is a four note chord that includes the fourth note of the tonic scale. The "7" refers to a note seven diatonic steps up from the fundamental note of the chord, not the seventh note of the tonic scale.
Traditional tonal music is described in terms of a scale of notes. On the notes of that scale are built chords. Chords in order form a progression. Progressions establish or deny a particular chord as being the tonic chord. The cadence is held to be the sequence of chords which establishes one chord as being the tonic chord; more powerful cadences create a greater sense of closure and a stronger sense of key. Chords have a function when it can be explained how they lead the music towards or away from a particular tonic chord. When the sense of which tonic chord is changed, the music is said to have "changed key" or "modulated". Roman numerals and numbers are used to describe the relationship of a particular chord to the tonic chord.
The techniques of accomplishing this process, are the subject of tonal music theory and compositional practice.
In 1821 Castil-Blaze used tonalité for what he called cordes tonales (today primary triads), the tonic, fourth (subdominant), and fifth (dominant). All other chords were cordes melodiques. Hugo Riemann defined tonality as, "the special meaning [functions] that chords receive through their relationship to a fundamental sonority, the tonic triad."
Fétis (1844) defined tonality, specifically tonalité moderne as the, "set of relationships, simultaneous or successive, among the tones of the scale," allowing for other types de tonalités among different cultures. Further he considered tonalité moderne as "trans-tonic order" and tonalité ancienne "uni-tonic order", trans-tonic meaning simply that the dominant seventh both establishes the key and allows for modulation to other keys. He described his earliest example of tonalité moderne: "In the passage quoted here from Monteverdi's madrigal (Cruda amarilli, mm.9-19 and 24-30), one sees a tonality determined by the accord parfait [root position major chord] on the tonic, by the sixth chord assigned to the third and seventh degrees, by the optional choice of the accord parfait or the sixth chord on the sixth degree, and finally, by the accord parfait and, above all, by the unprepared seventh chord (with major third) on the dominant." (p.171)
Fétis believed that tonality, tonalité moderne, was entirely cultural, "For the elements of music, nature provides nothing but a multitude of tones differing in pitch, duration, and intensity by the greater or least degree...The conception of the relationships that exist among them is awakened in the intellect, and, by the action of sensitivity on the one hand, and will on the other, the mind coordinates the tones into different series, each of which corresponds to a particular class of emotions, sentiments, and ideas. Hence these series become various types of tonalities." (p.11f) "But one will say, 'What is the principle behind these scales, and what, if not acoustic phenomena and the laws of mathematics, has set the order of their tones?' I respond that this principle is purely metaphysical [anthropological]. We conceive this order and the melodic and harmonic phenomena that spring from it out of our conformation and education." (p.249) In contrast, Hugo Riemann believed tonality, "affinites between tones" or Tonverwandtschaften, was entirely natural and, following Moritz Hauptmann (1853), that the major third and perfect fifth were the only "directly intelligible" intervals, and that I, IV, and V, the tonic, subdominant, and dominant were related by the perfect fifths between their roots. (Dahlhaus 1990, p.101-2)
By the 1840s the practice of harmony had expanded to include more chromatic notes, a wider chord vocabulary, particularly the more frequent used of the diminished seventh chord - a four note chord of all minor thirds which could lead to any other chord. It is in this era that the word "tonality" becomes more commonly used. At the same time the elaboration of both the fugue and the sonata form in terms of key relationships becomes more rigorous, and the study of harmonic progressions, voice leading and ambiguity of key becomes more precise.
Theorists such as Edward Lowinsky, Hugo Riemann, and others pushed the date at which modern tonality began, and the cadence began to be seen as the definitive way that a tonality is established in a work of music (Judd, 1998).
In response Bernhard Meier instead used a "tonality" and "modality", modern vs ancient, dichotomy, with Renaissance music being modal. The term modality has been criticized by Harold Powers, among others. However, it is widely used to describe music whose harmonic function centers on notes rather than on chords, including some of the music of Bartók, Stravinsky, Vaughan Williams, Charles Ives and composers of minimalist music. This and other modal music is broadly and generally considered tonal.
In the early 20th century the vocabulary of tonal theory is decisively influenced by two theorists: composer Arnold Schoenberg whose Harmonielehre (Theory of Harmony) describes in detail chords, chord progressions, vagrant chords, creation of tonal areas, voice leading in terms of harmony. To Schoenberg, every note has "structural function" to assert or deny a tonality, based on its tendency to establish or undermine a single tonic triad as central. At the same time Heinrich Schenker was evolving a theory based on expansion of horizontal relationships. To Schenker the background of every successful tonal piece is based on a simple cadence, which is then elaborated and elongated in the middleground and the foreground. Though adherents of the two theorists argued back and forth, in the mid-century a synthesis of their ideas was widely taught as "tonal theory", most particularly Schenker's use of graphical analysis, and Schoenberg's emphasis on tonal distance.
The practice of jazz developed its own theory of tonality, stating that while the cadence is not central to establishing a tonality—the presence of the I and V chords and either the IV or ii chord in progression is. This theory emphasized the play of modal elements against tonal elements, in an effort to allow improvisation, and inflection of standard melodies. Among theorists influenced by this view are Meier, Schillinger and the be-bop school of Jazz.
While many regard the works of Schoenberg post 1911 as "atonal," one influential school of thought, to which Schoenberg himself belonged, argued that chromatic composition led to a "new tonality", this view is argued by George Perle in his works on "post diatonic tonality". The central idea of this theory is that music is always perceived as having a center, and even in a fully chromatic work, composers establish and disintegrate centers in a manner analogous to traditional harmony. This view is highly controversial, and remains a topic of intense debate.
However, tonality may be considered generally with no restrictions as to the date or place at which the music was produced, or (very little) restriction as to the materials and methods used. This definition includes much non-western music and western music before 17th century. By the middle of the twentieth century, it had become "evident that triadic structure does not necessarily generate a tone center, that nontriadic harmonic formations may be made to function as referential elements, and that the assumption of a twelve-tone complex does not preclude the existence of tone centers" (Perle 1991, 8). Much music that is commonly described as tonal is actually nonfunctional tonality such as in that of Claude Debussy, Steve Reich, Aaron Copland and many others. Centric is sometimes used to describe music which is not traditionally tonal but which nevertheless has a relatively strong tonal center. See: pitch center. Often the term "common practice tonality" is used specifically to refer to tonal music that utilizes the diatonic system of tonic/dominant relationship, whereas "tonal" or "tonality" refers more broadly to describe any music or musical practice that relies on or exhibits tonal centers and/or modalities, often with triadic organization and relatively consonant harmonies.
In the early 20th century, the tonality which had prevailed since the 1600s was seen to have reached a crisis or break down point. Because of the "increased use of ambiguous chords, the less probable harmonic progressions, and the more unusual melodic and rhythmic inflections", the syntax of functional harmony was loosened to the point where "At best, the felt probabilities of the style system had become obscure; at worst, they were approaching a uniformity which provided few guides for either composition or listening" (Meyer 1967, 241). This led to a series of responses, many of which were considered irreconcilable with tonal theory or tonality at all. At the same time, other composers and theorists maintained that tonality had been stretched but not broken. This led to more technical vocabularies to describe tonality, including pitch classes, pitch sets, graphical analysis, and describing works in terms, not of their notes, but of their dominant intervals.
While tonality is the most common form of organizing Western Music, it is not universal, nor is the seven-note scale universal. However, Alfred Einstein wrote, regarding the ancient civilizations, that in ancient China "the development from the non-semitonal pentatonic to the seven-note scale is certainly traceable, even though the old pentatonic always remained the foundation of its music" (Einstein 1954, 7). He similarly notes the same kind of thing regarding ancient Japan, and Java. Much folk music and the art music of many cultures focus on a pentatonic, or five-note scale, including Beijing Opera, the folk music of Hungary, and the musical traditions of Japan.
Pre-classical concert music was largely modal, as is much folk and some popular music. In the early 20th century many techniques were developed and applied to tonal music, such as non-tertian secundal or quartal music. Some, such as Benjamin Boretz, consider tonal theory a specific part of atonal theory or musical set theory, which is in turn part of a more general theory of music. Many composers such as Darius Milhaud and Philip Glass have been interested in bitonality. While at one point in the middle of the 20th century the influence of atonality was such that many classical composers interested in the twelve tone technique and serialism declared tonality "dead," the postmodern age of composition which began in the mid-1970s with the advent of minimalism has been characterized by a dramatic return to the use of tonality by composers, especially in the U.S. Other composers such as Alan Hovhaness, Samuel Barber, Benjamin Britten, Erich Wolfgang Korngold, and Lou Harrison, never abandoned tonality in the general sense, even at the height of atonal modernist influence in the middle decades of the 20th century.
Tonality allows for a great range of musical materials, structures, meanings, and understandings. It does this through establishing a tonic, or central chord based on a pitch which is the lowest degree of a scale, and a somewhat flexible network of relations between any pitch or chord and the tonic similar to perspective in painting. This is what is meant by tonality having a hierarchical relationship, one triad, the tonic triad, is the "center of gravity" to which other chords are supposed to lead. Changing which chord is felt to be the tonic triad is referred to as "modulation". As within a musical phrase, interest and tension may be created through the move from consonance to dissonance and back, a larger piece will also create interest by moving away from and back to the tonic and tension by destabilizing and re-establishing the key. Distantly related pitches and chords may be considered dissonant in and of themselves since their resolution to the tonic is implied. Further, temporary secondary tonal centers may be established by cadences or simply passed through in a process called modulation, or simultaneous tonal centers may be established through polytonality. Additionally, the structure of these features and processes may be linear, cyclical, or both. This allows for a huge variety of relations to be expressed through dissonance and consonance, distance or proximity to the tonic, the establishment of temporary or secondary tonal centers, and/or ambiguity as to tonal center. Music notation was created to accommodate tonality and facilitates interpretation.
The majority of tonal music assumes that notes spaced over several octaves are perceived the same way as if they were played in one octave or octave equivalency. Tonal music also assumes that scales have harmonic implication or diatonic functionality. This is generally held to imply that a note which has different places in a chord will be heard differently, and that therefore there is not enharmonic equivalency. In tonal music chords which are moved to different keys, or played with different root notes are not perceived as being the same, and thus transpositional equivalency and far less still inversional equivalency are not generally held to apply.
A successful tonal piece of music, or a successful performance of one, will give the listener a feeling that a particular chord — the tonic chord — is the most stable and final. It will then use musical materials to tell the musician and the listener how far the music is from that tonal center, most commonly, though not always, to heighten the sense of movement and drama as to how the music will resolve the tonic chord. The means for doing this are described by the rules of harmony and counterpoint (some influential theorists prefer the term "thoroughbass" instead of harmony, but the concept is the same). Counterpoint is the study of linear resolutions of music, while harmony encompasses the sequences of chords which form a chord progression.
Though modulation may occur instantaneously without indication or preparation, the least ambiguous way to establish a new tonal center is through a cadence, a succession of two or more chords which ends a section and/or gives a feeling of closure or finality, or series of cadences. Traditionally cadences act both harmonically to establish tonal centers and formally to articulate the end of sections, just as the tonic triad is harmonically central, a dominant-tonic cadence will be structurally central. The more powerful the cadence, the larger the section of music it can close. The strongest cadence is the perfect authentic cadence, which moves from the dominant to the tonic, most strongly establishes tonal center, and ends the most important sections of tonal pieces, including the final section. This is the basis of the "dominant-tonic" or "tonic-dominant" relationship. Common practice placed a great deal of emphasis on the correct use of cadences to structure music, and cadences were placed precisely to define the sections of a work. However, such strict use of cadences gradually gave way to more complex procedures where whole families of chords were used to imply particular distance from the tonal center. Composers, beginning in the late 18th Century began using chords (such as the Neapolitan, French or Italian Sixth) which temporarily suspended a sense of key, and by freely changing between the major and minor voicing for the tonic chord, thereby making the listener unsure whether the music was major or minor. There was also a gradual increase in the use of notes which were not part of the basic 7 notes, called chromaticism, culminating in post-Wagnerian music such as that by Mahler and Strauss and trends such as impressionism and dodecaphony.
One area of disagreement, going back to the origin of the term tonality, is whether, and to what degree, tonality is "natural" or inherent in acoustical phenomena, and whether, and to what degree, it is inherent in the human nervous system, or a psychological construct and, if the latter, whether it is inborn or learned, or some combination of these possibilities (Meyer 1967, 236). A viewpoint held by many theorists since the third quarter of the 19th century holds that diatonic scales and tonality arise from natural overtones (Riemann 1872, 1875, 1882, 1893, 1905, 1914–15; Schenker 1906–35; Hindemith 1937–70), following the publication in 1862 of the first edition of Helmholtz's On the Sensation of Tone (Helmholtz 1877).
Rudolph Réti differentiates between harmonic tonality, of the traditional kind found in homophony, and melodic tonality, as in monophony. In the harmonic kind tonality is produced through the V-I chord progression. He argues that in the progression I-x-V-I (and all progressions), V-I is the only step "which as such produces the effect of tonality," and that all other chord successions, diatonic or not, being more or less similar to the tonic-dominant, are "the composer's free invention." He describes melodic tonality as being "entirely different from the classical type," wherein, "the whole line is to be understood as a musical unit mainly through its relationship to this basic note [the tonic]," this note not always being the tonic that would be interpreted according to harmonic tonality. His examples are ancient Jewish and Gregorian chant and other Eastern music, and he points out how these melodies often may be interrupted at any point and returned to the tonic, yet harmonically tonal melodies, such as that from Mozart's The Magic Flute below, are actually "strict harmonic-rhythmic pattern[s]," and include many points "from which it is impossible, that is, illogical, unless we want to destroy the innermost sense of the whole line." (Reti, 1958)
Consequently, he argues, melodically tonal melodies resist harmonization and only reemerge in western music after, "harmonic tonality was abandoned," as in the music of Claude Debussy: "melodic tonality plus modulation is [Debussy's] modern tonality." (page 23)