Tonality - Theoretical Underpinnings

Theoretical Underpinnings

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 the lowest pitch, or degree, of a scale, and using a somewhat flexible network of relations between any pitch or chord and the tonic, similar to perspective in painting. Tonality has a hierarchical structure: one triad, the tonic triad, is the center to which other chords are supposed to lead.

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. Temporary secondary tonal centers may be established by cadences, or simply passed through in a process called modulation, while 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 consonance and dissonance, distance or proximity to the tonic, the establishment of temporary or secondary tonal centers, and ambiguity as to tonal center. Music notation was created to accommodate tonality and facilitate 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 means a note which has different places in a chord will be heard differently, thus 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; transpositional equivalency and especially inversional equivalency are not considered applicable.

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 (or throughbass) and counterpoint. 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, gives a feeling of closure or finality, or both. 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. These temporarily suspended a sense of key, and by freely changing between the major and minor voicing for the tonic chord, they made the listener unsure of 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 tonality is natural or inherent in acoustical phenomena, whether it is inherent in the human nervous system or a psychological construct, whether it is inborn or learned, and to what degree it is all these things (Meyer 1967, 236). A viewpoint held by many theorists since the third quarter of the 19th century, following the publication in 1862 of the first edition of Helmholtz's On the Sensation of Tone (Helmholtz 1877), holds that diatonic scales and tonality arise from natural overtones (Riemann 1872, 1875, 1882, 1893, 1905, 1914–15; Schenker 1906–35; Hindemith 1937–70).

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 (the term coined independently and 10 years earlier by Estonian composer Jaan Soonvald (Rais 1992, 46)) 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 ," this note not always being the tonic as 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," and include many points "from which it is impossible, that is, illogical, unless we want to destroy the innermost sense of the whole line" to return to the tonic (Reti 1958).

Play normally and compare with impossible return after B♮

x = return to tonic near inevitable

ⓧ (circled x) = possible but not inevitable

circle = impossible

(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 modern tonality" (Reti 1958, 23).