Tonality is the sense of a note being a reference point. This note is called a tonic or tonal center. There are several kinds of tonality. The most common is functional tonality, sometimes just called tonality. Some musicians use the terms tonality and tonic only in connection with functional tonality, and pitch centricity and tonal center only in connection with other kinds.

History and etymology

Today, most musicians agree that functional tonality first took shape in the seventeenth century, and that other kinds of tonality (including the absence of tonality) appeared in the twentieth- and twenty-first centuries. Many musicians also describe earlier and/or non-Western music in terms of tonality, but the objectivity and relevance of such descriptions are not always clear, because tonality is a learned perception, not a property of sound. Even in the case of late-seventeenth- and eighteenth-century music, the terms tonal and tonality are anachronistic, even if they are useful, in the sense that the term tonality (tonalité in French) did not appear until the nineteenth century (specifically with Alexandre-Étienne Choron in 1810), and it became widespread only around the turn of the twentieth century. The nature of music perception in the eighteenth century is currently a matter of intense research.

Some musicians use the term tonal to refer to music of what they call the common-practice period (ca. 1650–1900). This usage is typically but not always paired with the term post-tonal to refer to music post-1900, which tends to imply that tonality itself somehow came to an end (which some have actually claimed, despite a wealth of evidence to the contrary). This dubious notion of post-tonality serves to privilege non-tonal music as progressive and post-1900 tonal music as regressive.

While a number of other metaphors have circulated over the years, today many musicians treat the metaphor of centricity as inoffensive and sufficient to synopsize tonality. Howere, on the one hand, some musicians reject the notion of tonal centricity, for example because tonics show up at endpoints, not midpoints. On the other hand, American theorist Dmitri Tymoczko has recently proposed a more elaborate definition of tonality as a sense conveyed by not only tonal centers but also stepwise melodic motion, consonance, relatively few kinds of chords, and scales with relatively few notes. In addition, the Russian theorist Yuri Kholopov has distinguished ten types of tonality according to whether there is an unambiguous tonic, whether there is a definite tonic chord, whether dissonance is resolved, and whether there is harmonic function. Kholopov’s theories have been extremely influential in Russia but have just begun to become known in the west.

General factors

Six main factors can work together to make a note sound like a tonic:

• Accent (emphasis), especially:
  • rhythmic accent (beginning or ending ideas, or being longer than other notes)
  • metric accent (coming on a strong beat)
  • dynamic accent (being louder)
  • textural accent (being with a thicker or thinner sound than other notes)
  • registral accent (being highest or lowest)
  • structural accent (beginning or ending phrases or sections)
• Repetition, especially repetition of accents
• Stepwise approach, especially by half step
• Being the root of an interval or chord, sounded melodically or harmonically
• Being in a diatonic, pentatonic, or acoustic scale
• Harmonic function

Specific types

Functional tonality

Functional tonality is the sense of a tonic produced by harmonic function (tonic, pre-dominant, and dominant). Harmonic function is so effective that it can point out the tonic without ever sounding a tonic triad. However, it never acts alone. Notice that in species counterpoint, a model of harmony and voice leading in functional tonality, the tonic is indicated through rhythmic accent (it is longer), structural accent (it ends the phrase), stepwise approach (in the upper voice), being a root (of the tonic triad, sounded melodically and harmonically),  diatonic scales (major and minor), and harmonic function (tonic at the beginning and dominant–tonic at the end).

Some musicians think that dominant function can be projected by chords other than V and VII, particularly in pop music. Alternatively, some musicians think of harmonic function in terms of the projection of a scale degree as a root, so that there are seven functions instead of three. If either of these broader conceptions is adopted, then the body of music that can be called functionally tonal is considerably larger.

It is important to recognize that harmonic function can also appear, at least fleetingly, in situations, described below, where the sense of a tonic is blurred or erased.

Non-functional tonality and pitch centricity

Non-functional tonality is a sense of tonic that avoids harmonic function. Non-functional tonality often still uses diatonic, pentatonic, and/or acoustic scales.

Example: Claude Debussy, “La cathédrale engloutie,” No. 10 from Preludes, Book 1 (1910): The piece drifts through different tonics but clearly projects C at the culmination and later in its reprise with a diatonic melody and a tonic pedal point.

For music in which harmonic function is hardly a reference point, the term “pitch centricity” is more appropriate.

Example: FC Kahuna, “Hayling,” from Machine Says Yes (2002): The progression is I–III–VII–IV, which is almost entirely by descending fourths instead of fifths as in functional tonality; moreover, the apparent scale is dorian.

Bitonality

Bitonality is the sense of two different tonics at once. The different tonics will generally have different registers and scales. Bitonality belongs to a broader category of polytonality (the sense of two or more tonics at once), but practically speaking it is extremely difficult to produce polytonality beyond bitonality. Bitonality is often confused with polychords. While it is possible to have a rudimentary sense of two tonics from just two simultaneous chords, bitonality generally involves more factors–namely accents, repetition, and melodic expression of chords. Bitonality is also sometimes confused with modal mixture, the use of different keys with the same tonic.

Example: The Beatles, “Revolution No. 9,” from The Beatles (1968). Amongst the components of this psychedelic sound collage are overlapping musical snippets with different tonics. For example, at 1:44, the oboe figure has a different tonic than the choral/orchestral clip. 

Example: Stephen Hough, Sonata for Piano (“Broken Branches”) (2010), mm. 186–191, “freddo” (cold), scroll to 10:10. The left hand focuses on Eb and the right hand focuses on E, B, and finally Eb.

Fluctuating tonality

Fluctuating tonality is the sense of competing tonics (Arnold Schoenberg). Often there are two main tonics a third apart. It is not just a matter of modulating back and forth but of continual tonal instability.

Example: Kristin Hersh, “Velvet Days,” from Hips and Makers (1994). Most of the song seems to be in D major, but it keeps returning to beguilingly ambiguous E7 chord, so the tonality remains loose. Only at the end does the key of A major emerge that has unsettled the song with its dominant.

Example: Richard Wagner, Prelude to Tristan und Isolde (1857–1859). The prelude fluctuates mainly between A minor and C major. Many people regard this sensual piece as the beginning of modern music.

Suspended tonality (non-tonality)

Suspended tonality or non-tonality is the erasure of the sense of a tonic (Arnold Schoenberg). The word suspended refers to all indications of tonics canceling each other out. Many musicians call non-tonality atonality, but this term has lost favor in some circles, not least because the term atonal originated as a derogatory term and retains a negative association.

Example: Frank Zappa, “The Chrome-plated Megaphone of Destiny” from We’re Only in It for the Money (1968)

Example: Olivier Messiaen, Quartet for the End of Time (1941), I (“Liturgy of Crystal”). Weak tonics might be heard in the violin and clarinet, but not in the cello or piano, and the overall effect is of none.

Further reading

• Stephen Kostka, Materials and Techniques of Post-Tonal Music, Chapter 5
• Vincent Persichetti, Twentieth-Century Harmony, Chapter 12
• Miguel Roig-Francolí, Understanding Post-Tonal Music, Chapters 1 and 5
• Joseph Straus, Introduction to Post-Tonal Theory, Chapter 4

External links

The Wikipedia article on tonality is ill-informed, poorly written, and not unified.