A time scale specifies divisions (scale) of time.

• A time standard is a specification of either the rate at which time passes, or points in time, or both.
• A duration is a quantity of time.
• A rhythm is a temporal pattern of events, especially in music.
• The geological time scale divides up the history of the Earth into scientifically meaningful periods.

There is also a wiki, called WikiTimeScale, which deals with historic events displayed on a user-defined time scale.

Musical time scales

In music, Curtis Roads (2001, p.3-4) distinguishes nine time scales of music:

1. Infinite: literally infinite, such as the length of sine waves in classical Fourier analysis,
2. Supra: months, years, decades, and centuries; everything above the level of
3. Macro: "overall musical architecture or form" or the level of the individual piece; minutes, hours, or even days,
4. Meso: "Divisions of form" including movements, sections, phrases; seconds and minutes,
5. Sound object (Schaeffer 1959, 1977): "a basic unit of musical structure" and a generalization of note (Xenakis' ministructural time scale); fraction of a second to several seconds,
6. Micro: "sound particles" (see granular synthesis) down to the threshold of audible perception; thousands to millionths of seconds,
7. Sample: sample (music), measured as are samples in millionths of a second or microseconds,
8. Subsample: changes "too brief to properly recorded or perceived", billionths of a second, nanosecond, or less, and
9. Infinitesimal: literally "infinitely brief" such as delta functions.

Music may, however, exist "outside" of time when structured through "principles whose defnitions does not imply a temporal order", including scales and many other precompositional techniques, musical instruments, and aleatoric music. Examples such as sound installations in which the order of the sound is determined by, for example, a listeners movement through the system, are thus placed in time. (ibid, p.38)

Source

• Roads, Curtis (2001). Microsound. MIT. ISBN 0262182157.

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