Microtonal music is made of notes "between the cracks" on an ordinary instrument. On a piano, for example, each octave is (theoretically) divided into twelve equal semi-tones or half-steps. This system of tuning is called twelve-tone equal temperament because the intervals between the twelve tones are equal, and it represents a tempering of the Pythagorean scale, created by superimposing the 3:2 frequency intervals found among the natural harmonics produced by any object vibrating with a definable pitch. All the intervals in this ancient scale are not equal, so they are tempered (their tuning is changed slightly) to create twleve-tone equal temperament. Older systems of temperament "averaged out" the Pythagorean scale in other ways. Temperament is a problem that musicians and theorists have confronted for centuries.

"Microtonal" is a blanket term. It denotes any system of temperament, tuning or music that deviates from twelve-tone equal temperament. Notable composers of microtonal music include Harry Partch, Ivor Darreg, Ben Johnston, Lou Harrison, LaMonte Young, Terry Riley and Pauline Oliveros. Some microtonalists compose music for instruments "detuned" according to Just intonation, which contains only intervals with fundamental frequencies in low-number or prime ratios. Some apply other equal divisions to the octave e.g. 19tET (nineteen-tone equal temperament) and 53tET to name two. And some create music based on the theoretical non-division of the octave.

Some composers of microtonal music make their own instruments. Harry Partch earned his place as a modern pioneer building instruments on which to perform his music and writing a book describing his system. He designed and built the instrument above, called a Boo (it is made of bamboo), and the one at right, called Cloud Chamber Bowls. Ben Johnston is known for piano pieces specifying that the piano be "detuned" according to very precise instructions. Pauline Oliveros plays a "detuned" accordion. With the advent of electronic instruments, composers are able to create "detuned" scales with greater ease and accuracy.

Some of my music is microtonal. I use computer programs, synthesizers and samplers that can realize exact tuning specifications. I developed a system of relating pitches to one another, based on relationships between the harmonics of any naturally-occurring, pitched sound. My dissertation is composed according to this system, and there is a paper (in dire need of being updated in light of new deveopments) that explains it: "Ratiotonic Temperament: A Proposal for the Organization of Tones in Art Music as a 'Microtonal' Alternative to Twelve-Tone Equal Temperament." Read it here, read a more contemporary and scholarly presentation of it here, and feel free to e-mail me.

• See "Links: Other Tuning-related Sites on the 'Net'" at The Just Intonation Network
• Microtonal Synthesis  A database of nearly every make, model or type of electronic instrument ever heard of, in or out of production, listed according to their microtonal capabilities
• The Centre for Microtonal Music in London
• Interval: Journal of Music Research and Development Published from 1978-87, addresses microtonal music; distributed by its editor, Jonathan Glasier.
• Pitch: For the International Microtonalist  A four-volume set of reference materials published between 1986-90 by the American Festival of Microtonal Music
• Music Works  A magazine that often has information on microtonal music
• Xenharmonikôn: An Informal Journal of Experimental Music  Since 1974, the BEST current publication on the subject, seeks to address all aspects of microtonal music; distributed by: Frog Frog Peak Music
• BIBLIOGRAPHY and DISCOGRAPHY  Maintained by: Huygens-Fokker Foundation's Centre for Microtonal Music in Amsterdam -- includes a huge, well-maintained clearing house of information and links on microtonal music.
• Scala Home Page  Scala is software tool for experimentation with musical tunings.
• Peterson Stringed Instruments  Custom designed microtonal stringed instruments
• Notation for Microtonal Scales  For 31-tone equal temperament, similar to that by Adriaan Fokker
• "About 31-Tone Equal Temperament"  Another good article on this subject.
• Recommended Listening in Microtonal Synthesis  Breifly annotated, with links to pages about many of the composers
• FreeNote Music  Microtonal guitars and recordings
• Lucy Scale Developments  A lot to annotate here; go check it out!
• Microtonal Music  Links to microtonal music sites; maintained by John Starrett, Assistant Professor of Mathematics at New Mexico Tech.
• MicroFest 2001