History and philosophy of xenharmonic music

Xenharmonic Music: A Brief History and Philosophy

[This article is a refined and expanded version of a discussion that originally took place on the Xenharmonic Alliance Discord server. Encouraged by the positive reception and thoughtful feedback it received, I decided to develop it into a more structured and formal piece, with the hope that it will serve as a valuable resource for others interested in the subject.]

Introduction

Xenharmonic music is commonly defined as music composed outside the bounds of 12-tone equal temperament—the standard tuning system in Western music, and increasingly, across much of the world. While this definition is broadly accurate and useful as a starting point, it also invites a number of important questions. For instance: do historical temperaments qualify as xenharmonic? What about the diverse intonational practices found in folk and traditional musics around the world? Does the prefix xen- (meaning "foreign" or "strange") suggest that once a xenharmonic system becomes familiar, it ceases to be xenharmonic? And if so, under what circumstances—if any—might 12-EDO itself be considered xenharmonic?

These are reasonable and thoughtful questions, but they often stem from a misunderstanding that arises through no fault of the inquirer. While it is commonly and intuitively understood that xenharmonic music involves exploring systems beyond 12-EDO—such as just intonation lattices, equal divisions of the octave, and novel temperaments—the underlying thread that historically and conceptually unites these approaches under the term xenharmonic is rarely articulated with clarity.

It is with great humility that I offer this modest contribution, in the hope that it may inspire curiosity and reflection, and help advance what I believe to be one of the most beautiful and unique developments in the history of music. Detwelvulate—and long live the Xenharmonic Alliance!

Setting the Stage

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Important Figures

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Harry Partch

In the early 20th century, Harry Partch came to a pivotal realization: that equal temperament, particularly the 12-tone system, was masquerading as just intonation while obscuring the vast and nuanced sonic possibilities inherent in pure harmonic relationships. In response, Partch dedicated his life to escaping what he saw as a musical prison. His work laid much of the conceptual and practical groundwork for what would later be recognized as xenharmonic music—designing entirely new instruments, formulating original tuning theories, and composing music that is fundamentally incompatible with standard 12-EDO. Partch embraced just intonation as a foundation, focusing particularly on the 11-limit, a region of the harmonic series that lies well beyond the reach of traditional Western tuning.

Ivor Darreg

Unlike some of his contemporaries, Ivor Darreg was not primarily known for groundbreaking theoretical innovations. Instead, his contribution lay in his unwavering dedication to making music, inventing instruments, and nurturing a space for this emerging musical practice to grow. Darreg worked tirelessly to connect like-minded individuals, helping to cultivate a community that would eventually give rise to numerous mailing lists, forums, servers, and publications. He is widely credited with the insight that every tuning system evokes its own distinct mood—and, perhaps most significantly, with coining the very term xenharmonic.

Clarifying the definition of xenharmonic music

This brings us to the heart of the matter: within this historical and cultural context, what did Ivor Darreg and the early members of the Xenharmonic Alliance intend to convey with the term xenharmonic? Why did they feel it aptly described their work and vision, and what meaning did it hold for them and those who followed? As previously noted, it is an oversimplification to define xenharmonic music merely as anything that falls outside of 12-tone equal temperament—a definition that fails to capture its deeper significance. Darreg himself recognized this limitation. As the community expanded, he and others felt compelled to clarify what, to them, was a self-evident concept but which could appear vague or ambiguous to newcomers or outsiders.

So while his early writings may use the term in a way that implies one is already familiar with what is being conveyed, by the late 80's he begins spelling it out more clearly. One early quote in this effort is from his 1988 Annual Report, in which he writes:

Xenharmonics, as most of you know, means a system of tuning or performing music that does not sound like a performance in the standard 12-tone equal temperament. It may or may not be tempered. But it has OTHER pitches than 12-tone-equal-tempered instruments have, and they are not limited to a set of 12 pitches per octave. To be xenharmonic, it has to sound different enough that most listeners would HEAR the differences and be aware of it. (It is possible to produce a set of pitches which most people cannot distinguish from 12-tone equal temperament, but which is arrived at by different mathematics or design, and we wish to exclude such systems from the definition because they will not help any composers to produce really new melodies and harmonies.) [emphasis mine]

In the same document:

With xenharmonics offering many alternatives to 12-tone, we must obviously explore unknown territory, and cannot depend upon the rules of traditional classical melody-writing and the well-worn patterns of concert-hall music to guide us into territories such as just intonation with 7- and 11-based intervals, or temperaments that bring in new tiny intervals and strange harmonies. Improvising singly or in small groups is the way to ensure that these new systems get properly and thoroughly explored. Using new instruments which are not tied to conventional playing techniques and timbres and constraints is another way to get sufficiently different from the 12-tone styles to be worth the trouble of moving to new paths.

As with much of Darreg’s writing, the entire document is well worth reading in full. However, for the purposes of this article, I will focus specifically on the passages in which he explicitly defines the meaning of xenharmonic. It is important to note that these reflections were written many years after the term had already been embraced by the community as a collective self-description. Again, from the same document:

Sure: a whole bunch of pestiferous legalistic nitpickers are descending on me right as I write this. Gray areas do exist: one would be, using 12 notes of Pythagorean. Is that xenharmonic? Probably not--listeners ordinarily could not tell the difference. 12 note forming a series of fifths, out of 53 or 41 or 29? Same answer as above. (You could juggle your choice of notes to make a difference, but this is deliberate stacking of the cards.) And what if you go to someone's home or recital hall and play their piano when it is horribly out of tune. Is that xenharmonic? I have the same privileges as the lawyer or theorist out there who would ask such a loaded question: did you keep on playing after the first few chords? If you stopped, you had no intention of playing xenharmonically, but if you kept on playing after you heard the terrible out-of-tune notes, then it was xenharmonic because you were willing to play them. Were others listening? How many blue notes or bends do you have to sing or play before it is xenharmonic? Well, how many angels can stand on the point of You Know What?

In the same year, Darreg wrote a document explicitly laying out the definitions of the terms the community had adopted. Among them is "xenharmonics." From Defining One's Terms, 1988:

XENHARMONICS: Any system of tuning which does not sound like the ordinary standard twelve-tone equal temperament. That is,a tuning is xenharmonic if most musically-trained or musically-inclined listeners to a permanence hear it as different from a performance in 12-tone equal temperament. Nearly all just-intonation performances are xenharmonic. The only exception would be where so few just pitches are used that no interval noticeably different in a real performance of apiece of music from the nearest 12-tone-tempered interval can be heard. (The subset of just intonation called Pythagorean by most writers, if not carried out to many pitches, might be too close to the 12-tone tempered pitches for the average music-listener to call it different enough.)

Certain of the 12-tones-per-octave-only-and-no-more UNequal temperaments would not be called xenharmonic because the deviation from 12-equal is too trivial to be heard in a normal performance. A wild style of performing with wide vibrato and/or deviations from 12-tone-equal or the use of pitch-fringes and double-tracking, would not be xenharmonic even though small intervals occurred, because there would still be only 12 pitch-classes and no use of that tiny intervals to progress beyond the limitations of the 12-tone equal temperament.

The just intervals 18:17 and 19:16 have been used in fretting guitars to approximate 12-tone temperament and even though they might theoretically be just, this is not xenharmonic. Nor is the complicated interval 89:84 or 196:185 as used in the Hammond gear-wheel organ. Most contemporary definitions of just intonation exclude complicated intervals used merely to simulate 12-equal. But if I don't spell this out here to the point of annoyance, somebody will complain.

Most non-twelve-tone equal and unequal temperaments are xenharmonic. Obviously quartertones (the 24-tone equal temperament) is tied to 12 and cannot be as xenharmonic as 23-tone or 25-tone. 6-tone equal temperament is CONTAINED in 12, and therefore cannot be xenharmonic.

We can't provide a perfectly airtight definition because all human beings have different ears and hearing, and the same person hears differently at different times. It's like demanding to know what day and month and year I became bald, or do I still have enough hair on the sides of my head to be considered not quite bald? Does fuzz count or not? Such hairsplitting nonsense will not advance music one iota! So the present definition of XENHARMONIC says that nearly all just intonation is xenharmonic and most equal and unequal temperaments are xenharmonic and most pitch-deviations caused by organ vibrato and effect-box chorusing and flanging and most slight bends by violinists are not xenharmonic because they do not leave the 12-equal standard tolerance range.

In my view, Darreg’s magnum opus is one of his longest and final writings, composed when he was around 73 years old. By that time, nearly a century had passed since Harry Partch's birth, and the Xenharmonic Alliance had already been active under that name for several decades. The document, titled Opening the Door to the 90’s, offers further clarifications of xenharmonic principles, while also delivering impassioned and celebratory reflections on the hard-earned recognition and maturation of the xenharmonic movement. From the document:

One case where I do not want the term "xenharmonic" to apply is the many slight variations of keyboard tuning where for example a temperament with 12 pitches per octave is slightly unequal. Many systems of this type have been invented during the last three centuries or so, to make the keys close to C major on the ordinary keyboard instrument sound somewhat smoother at the expense of key near F# major which will sound rougher. I many cases these alterations of the inequality of tempering is so slight that listeners have to attend closely to notice any difference. I am a composer and I do not want everything I composer or improvise to sound like what somebody else has already done--maybe better! And as a matter of pride I want to enlarge the composer's vocabulary of melodies, harmonies and moods.

The term "xenharmonics" includes both equal and unequal temperaments, and it also includes just intonation and some other systems, in those cases where to the average listener, the music does not sound the same as if it had been performed in the customary standard 12-tone equal temperament. I cannot repeat a certain warning too often: 12 pitches taken out of a system having or needing more than twelve pitches per octave, are not enough!

Related to why the work of him and others going back to Partch was important to him, and thus why the definition of xenharmonic and the purpose of the Xenharmonic Alliance mattered, he wrote:

Some commercial interests are doing all they can to Plan Obsolescence and make music records perish all the quicker. They care absolutely nothing for serious new music nor its composers, and do not want to help inventors or builders of new instruments either. As I am writing this, there are persons who do not want any of my music in new scales to be heard and have told me so with other persons present, so you do not have to take my word for it. Nor am I the only victim. It is too late for such persons the stop the Xenharmonic movement, because it has been growing all during this 20th Century, underground at first, but now that the means of performing and recording and copying recordings in non-twelve have become affordable, these recordings have been circulated to so many places that now it would be impossible to erase all my tapes and even more out of the question to erase the tapes of a hundred or more other persons producing them today.

Final Discussion (TL;DR)

So having explored this topic, let me now return some of the questions and statements that prompted the exploration.
Can a distinction be made between xenharmonic music and non-xenharmonic music?

Yes

Should such a distinction be made?

Yes

Is such a distinction often made in practice?

Yes

Is xenharmonic synonymous with microtonal?

No

Does xenharmonic mean "weird music" generally?

No

Is xenharmonic a relative term? can 12edo be xenharmonic to someone in Bali? Does 16 edo stop being xenharmonic when we get used to it?

No

Does xenharmonic just mean exploring tuning? Do piano and organ tuners practice xenharmonics when they make slight alterations to the 12 tone system for various reasons? Do guitarists practice xenharmonics when they do drop D tuning?

No

Is xenharmonic music just about abstract theory and recreational mathematics?

No

Xenharmonics is the term coined and adopted by the community that formed around a unique style of Western microtonality, and the Xenharmonic Alliance is that community. It is about new tonal organizations and instruments, new moods and music. It is about a musical practice first and foremost.