Tone clock

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The tone clock, and its related compositional theory tone-clock theory, is a post-tonal music composition technique, developed by composers Peter Schat and Jenny McLeod. Music written using tone-clock theory features a high economy of musical intervals within a generally chromatic musical language. This is because tone-clock theory encourages the composer to generate all their harmonic and melodic material from a limited number of intervallic configurations (called "intervallic prime forms", or IPFs, in tone-clock terminology). Tone-clock theory is also concerned with the way that the three-note pitch-class sets (trichords or "triads" in tone-clock terminology) can be shown to underlie larger sets, and considers these triads as a fundamental unit in the harmonic world of any piece. Because there are twelve possible triadic prime forms, Schat called them the "hours", and imagined them arrayed in a clock face, with the smallest hour (012 or 1-1 in IPF notation) in the one o'clock position, and the largest hour (048 or 4-4 in IPF notation) in the 12 o'clock position. A notable feature of tone-clock theory is tone-clock steering: transposing or inverting hours so that each note of the chromatic aggregate is generated once and once only.

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Relationship to pitch-class set theory and serialism

While tone-clock theory displays many similarities to Allen Forte's pitch-class set theory, it places greater emphasis on the creation of pitch fields from multiple transpositions and inversions of a single set-class, while also aiming to complete all twelve pitch-classes (the chromatic aggregate) with minimal, if any, repetition of pitch-classes. While the emphasis of tone-clock theory is on creating the chromatic aggregate, it is not a serial technique, as the ordering of pitch-classes is not important. However, it bears a certain similarity to the technique of serial derivation, which was used by Anton Webern and Milton Babbitt amongst others, in which a row is constructed from only one or two set-classes. It also bears a similarity to Josef Hauer's system of tropes, albeit generalised to sets of any cardinality.

Peter Schat

Peter Schat's Zodiac of the Hours, which graphically represents the tone-clock steerings of the twelve hours. X can only be steered as a diminished seventh tetrachord (hence, the only non-triangular shape). Each point of a shape represents a pitch-class on the chromatic circle, and each shape represents one transposition or inversion of an hour. Zodiac of the Hours.svg
Peter Schat's Zodiac of the Hours, which graphically represents the tone-clock steerings of the twelve hours. X can only be steered as a diminished seventh tetrachord (hence, the only non-triangular shape). Each point of a shape represents a pitch-class on the chromatic circle, and each shape represents one transposition or inversion of an hour.

The term tone clock (toonklok in Dutch) was originally coined by Dutch composer Peter Schat, in reference to a technique he had developed of creating twelve-note pitch fields by transposing and inverting a trichord so that all twelve pitch-classes would be created once and once only. [1] Schat discovered that it was possible to achieve a trichordally partitioned aggregate from all twelve trichords, with the exception of the diminished triad (036 or 3-10 in Forte's pitch-class set theory). Schat called the 12 trichords the "hours", and they became central to the harmonic organization in a number of his works. He created a "zodiac" of the hours, which shows in graphical form the symmetrical patterns created by the tone-clock steerings of the hours. (Hour X is substituted with its tetrachord, the diminished seventh, which can be tone-clock steered).

Jenny McLeod

In her as-yet-unpublished monograph Chromatic Maps, New Zealand composer Jenny McLeod extended and expanded Schat's focus on trichords to encompass all 223 set-classes, thus becoming a true tone-clock theory. [2] She also introduced new terminology in order to "simplify" the labelling and categorization of the set-classes, and to draw attention to the specific transpositional properties within a field.

The most succinct musical expression of the theory is in her 24 Tone Clock Pieces, written between 1988–2011. Each of these piano works explores different aspects of tone-clock theory.

McLeod's terminology

The following terms are explained in McLeod's Chromatic Maps I:

Mathematical generalizations of tessellating set-classes

New Zealand composer and music theorist Michael Norris has generalized the concept of tone-clock steering into a theory of pitch-class tessellation, and developed an algorithm that can provide tone-clock steerings, in 24TET. He has also written about and analyzed McLeod's tone clock pieces. [3] [4]

Related Research Articles

In music theory, a diatonic scale is any heptatonic scale that includes five whole steps and two half steps (semitones) in each octave, in which the two half steps are separated from each other by either two or three whole steps, depending on their position in the scale. This pattern ensures that, in a diatonic scale spanning more than one octave, all the half steps are maximally separated from each other.

In music, a tone row or note row, also series or set, is a non-repetitive ordering of a set of pitch-classes, typically of the twelve notes in musical set theory of the chromatic scale, though both larger and smaller sets are sometimes found.

In music theory, a tetrachord is a series of four notes separated by three intervals. In traditional music theory, a tetrachord always spanned the interval of a perfect fourth, a 4:3 frequency proportion —but in modern use it means any four-note segment of a scale or tone row, not necessarily related to a particular tuning system.

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References

  1. Schat, Peter (1993). Tone Clock (Contemporary Music Studies, vol. 7). Routledge.
  2. McLeod, Jenny (1994). "Chromatic Maps I & II". archive.org.
  3. Norris, Michael (2006). "Tessellations and Enumerations: generalizing chromatic theories". CANZONA: The Yearbook of the Composers Association of New Zealand: 92–100.
  4. Norris, Michael (2006). "Crystalline Aphorisms: commentary and analysis of Jenny McLeod's Tone Clock Pieces I–VII". Canzona: The Yearbook of the Composers Association of New Zealand: 74–86.