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In primary school we're still taught that there are seven notes, doremifasollasi? “Twelve” would be more accurate — shouldn't sharps and flats be counted too? But look closer: why exactly twelve, and why those twelve? Wouldn't thirteen, or nineteen, or twenty-four work just as well? The reasons are manifold: cultural, physical, mathematical, practical, and even political (before the 1955 ISO conference, every nation used its own different tuning frequencies) and spiritual (some insist that A should be set at 432 Hz rather than 440 Hz, to align with the “natural frequency” of life, the universe and everything). But none of that will be explored here, because the point of this playlist is to look beyond.

New spaces between the lines

If conforming to the twelve-note canon brings multiple, undeniable advantages, straying from it can also have its own logic. Systems based on a different division of pitches have been in use for millennia, are still employed in much non-European music, and — especially since the second half of the 20th century — have been adopted by numerous academic composers. For some time now, however, the possibility of drawing on notes "outside the spectrum" of the usual twelve has also caught the interest of a growing number of pop artists, especially in the electronic, metal and progressive fields.

Truth be told, this isn't an absolute novelty. Blue notes — slightly flattened "passing" notes introduced to heighten expressiveness — are a device that pop vocal style inherited very early on from blues and jazz, and without which Sinéad O'Connor's rendition of "Nothing Compares 2 U" would lose much of its magnetism. "These Boots Are Made For Walking", a song by Lee Hazlewood recorded by Nancy Sinatra in 1965, opens with a descending double-bass phrase that moves in steps of less than a semitone (technically speaking, then, it's a microtonal melody). And what about bending, glissando, slide — devices used to fill the space between the twelve notes, heavily exploited by generations of guitar heroes and a distinctive trait of the fretless sound of bassists like Percy Jones, John Giblin and Mick Karn?

There is, however, a difference between the examples just mentioned and the phenomenon of recent years: more and more artists today choose not to use "extra" notes merely as passing elements, as coloring inserted into an otherwise ordinary harmonic context, but rather to make them a cornerstone of their compositional vision. Alongside this, the range of instruments designed for the purpose keeps growing: refretted guitars (with frets placed in unconventional positions), electronic keyboards that break away from the usual black-key/white-key layout, and of course a good array of digital plugins that help musicians remap their MIDI instruments onto unconventional scales. In short, expanding one's harmonic palette to new notes has never been easier for a pop artist.

And it has never been easier to find support in one's own growth, either. A rather active community has sprung up online, complete with its own wiki, Facebook groups and a subreddit with several posts a day. And the podcast Now and Xen, launched in 2018 and available on multiple platforms, now has more than sixty episodes.

The fascination and potential of this playing field are illustrated by a page of the xenharmonic wiki itself (incidentally: the Greek root xen- means "other", "alien"). It cites reasons such as the search for "something new", the availability of sounds that are "more in tune" (but also, if desired, "less in tune") than usual ones, greater melodic and contrapuntal versatility, interest in the mathematical properties and coincidences of different temperaments, historical curiosity about musical systems used in the past, or the desire to move away from the Eurocentrism inherent in the dominant scheme.

More simply, though, one could argue that the drive toward microtonality and xenharmony (the two terms are often interchangeable) is essentially expressive in nature. Changing the map of usable pitches is, like changing meters or timbres, a way of expanding the space in which to create sensations. Disorienting or subtly odd, often forbidding but sometimes able to enchant on first listen, the emotional landscapes conjured up by xeno-rockers are an unexplored terrain to be entered gingerly — perhaps in search of some exotic or ramshackle flourish — or else to be dived into headlong, chasing some elusive compositional Holy Grail.

Of the fifty tracks that make up this article's companion playlist, the first dozen have been chosen for their accessibility. These are particularly immediate tracks, representative of the range of the scene, and if you haven't hit "play" yet, now might be the time. After that, the compilation — like the article — leaves its introductory phase behind to become more demanding and specialized.

Among the first names presented, some are fairly well known to alternative rock fans. Sufjan Stevens and King Gizzard & The Lizard Wizard are artists admired by millions of listeners; Horse Lords are a cult band whose reputation has grown considerably in recent years. While Stevens' forays into microtonal territory can be called occasional (tied in particular to his collaboration with his godfather Lowell Brams), King Gizzard and Horse Lords are decidedly habitués of xenharmony — to the point of ranking among its foremost champions in the rock world. Both make extensive use of electric guitars with modified fretboards.

On 2017's "Flying Microtonal Banana", the hyper-prolific Australian psych-prog-garage rockers draw on the Turkish stringed instrument known as the bağlama to introduce quarter tones into the possibilities of their instruments and heighten the exotic character of their jams. The 2020/21 double release "K.G." and "L.W." further expands their repertoire of Turkish-flavored riffs.

The hieratic sound of the American band Horse Lords, on the other hand, arises from a combination of minimalism, totalism, odd time signatures and rigorous harmonic proportions dictated by just intonation. Yet they bristle if anyone labels their music math-rock!

Other artists, less well known outside the inner circle, are nonetheless crucial reference points for the xenharmonic community. The "Hark Ye Music Lovers" project, created by the band An Exciting Event, brings together musicians of different backgrounds united by a passion for microtonality and by Moondog's eclectic musical style. "Nuclear Fusion", by Turkish musician Tolgahan Çoğulu, is the most recent work recorded with his versatile microtonal guitar, whose frets can be repositioned to accommodate different temperaments. Two progressive-minded bands, Ventrifacts and Mercury Tree, share the presence of multi-instrumentalist Ben Spees and mark a high point in songwriting craftsmanship within the xenharmonic field. Finally, the versatile composer Brendan Byrnes is a highly respected figure for the musicality of his work and the stylistic breadth of his explorations, ranging from post-rock to synth-pop, by way of exotica, ambient, shoegaze, IDM, dance music and progressive alt-rock (with the band Ilevens).

Mapping alien worlds

So far, we've proceeded without maps and with little theory. But now it's time to get into the substance: what would it even mean to "step outside the twelve notes"? And how can one do so while avoiding — unless that's actually the goal — descending into pure chaos?

Since every "pitch" recognized by our ear is tied to a frequency, venturing into the world of xenharmony means reshaping the pairings that currently dominate. Anyone who feels dizzy at the mere mention of the phrase "twelfth root" can safely skip this paragraph. Everyone else, buckle up: we'll need a bit of math (not too much, I promise).

The note-frequency mapping underlying almost all Western music (and beyond) of recent centuries is codified by equal temperament, which established itself from the eighteenth century onward. Here's a primer on its principles: a) two frequencies where one is double the other correspond to the same note, but on consecutive octaves; b) between the two "copies" an octave apart from one another sit eleven other notes, each a semitone's distance from the one before; c) the frequency ratio between two consecutive notes is always the same. The consequence of these postulates is that the frequency of C and that of C#, or that of C# and D, and so on, differ from one another by a factor equal to the twelfth root of two.

To explore other possibilities, it's enough to alter one or more of these three postulates. One route is to keep the general framework but divide the octave into a different number of parts: this produces the so-called "Edo scales" (Equal Division of the Octave), of which the familiar twelve-tone system is simply a special case (12-Edo). Alternatively, one can reject the idea of "equidistance" between adjacent notes and rely on some other method for mapping notes to frequencies: the most popular is Just Intonation (JI), which returns to the good old Pythagorean fixation on ratios between whole numbers. In the scheme devised by Pythagoras, and widely applied across Europe and elsewhere for centuries, the ratio between a C and a G is 3/2, between a C and an F it's 4/3, and every other interval corresponds to a ratio involving multiples of two and three: the more intricate the ratio, the less consonant the two notes sound.

Today the Pythagorean temperament described above is labeled "3-limit Just Intonation," because the highest prime number allowed in the ratios is 3. But many artists have turned instead to, say, 5-limit tuning, placing the frequency of A at 5/3 that of C rather than at the 27/16 of Pythagorean temperament, thereby achieving a more consonant interval.

Pushing things even further, some have thought to abandon octave equivalence altogether: one possible approach is the Bohlen-Pierce scale (BP to its friends), which is based not on the 2/1 ratio but on 3/1 — from C to the G an octave above.

There are, however, also less explicitly mathematical routes to approaching xenharmony: drawing on the musical systems of non-Western cultures can be a considerable source of inspiration, both for artists who have lived immersed in those sounds since birth, and for those who arrive at them through later listening and study. Islamic maqam, Indonesian gamelan and Indian raga are structured systems with long traditions, each built on its own harmonic notions and intervals that don't fit neatly into twelve-tone equal temperament. As early as the beginning of the twentieth century, music theorists in the Middle East began reducing the extreme variety of maqam scales and intervals to a temperament based on quarter-tones (today we'd call it 24-EDO). The situation is more complex with Indonesian percussion orchestras, whose music centers on two different note collections (known as pelog and slendro) that nonetheless show considerable tuning differences from orchestra to orchestra. Indeed, in the gamelan ensembles of the island of Bali, it's common for pairs of instruments of the same type to be tuned slightly differently from one another, so as to produce an acoustic beating (in Balinese, ombak, "wave") whose brilliance is said to be linked to spiritual elements such as the union of male and female.

The challenge of expression

None of the harmonic choices outlined above is, in itself, any guarantee of a composition's expressive effectiveness. Drawing on scales from established musical traditions also brings with it the possibility of falling back on tried-and-tested phrasing, note combinations that are emotionally "functional" in at least some cultural context. Adopting a "synthetic" scale like Edo or BP, by contrast, imposes a climb that offers very few footholds to whoever wants to take it on.

Scrolling through the playlist, one can start to get acquainted with the uses made of xenharmony across different stylistic contexts. Artists with an indie background like Jack Tickner and Jock Tears exploit the "detuned" sound of the new notes to reconnect with the "ramshackle" spirit of the rock of Guided by Voices, Pavement, Yo La Tengo, or the Ween of "Pure Guava". Theirs is, all things considered, a cautious approach, and certainly not much inclined toward theoretical abstraction: the goal isn't to abandon familiar melodic territory, but to smudge the harmonic palette to get a slightly rougher sound. The musical equivalent of ripped jeans, in short.

A first batch of artists tied to traditional expressive forms opens onto bolder prospects. Guitarist Jon Catler's Catler Bros play a jazz-blues-rock built on a just intonation system with 49 intervals per octave, while Neil Haverstick's country/blues settles, on "667", for "just" 19. In both cases, the result is virtuosic and firmly rooted in blues expressiveness. More adventurous are multi-instrumentalist Max Muntz's Vex Collection, whose mix of traditional instruments (bombard, Scottish bagpipes, Korean taepyeongso, Croatian creski meh and various percussion) creates a decidedly progressive and evocative assault.

A large portion of the tracklist is devoted to electronic projects: it's precisely in this field that technological progress has led to the greatest breakthroughs in recent times, with instruments like the Lumatone and the Continuum Fingerboard. Some of the artists featured are prominent figures on the scene: Alaska-based Dolores Catherino is a theorist and experimenter active for over a decade (on YouTube you can watch her 2016 TEDx talk); Belgian biologist Sintel has since 2019 been tinkering with xenharmonic ambient, chiptune and jazz, also made with software he designed himself. There's also a sizeable population of xeno-musicians working in the IDM and drum'n'bass fields: alongside a heavyweight of the scene like Aphex Twin, three other important names on the landscape are Australia's Xotla, America's Acreil and Britain's Sevish (founder of the Now and Xen podcast).

The chromatic possibilities offered by xenharmony (which Catherino, not coincidentally, calls "polychromy") are indeed a godsend for genres that have always centered on evoking unusual soundscapes and subtle emotional metamorphoses. In drum'n'bass and related fields, meanwhile, the game is often about mindfuck, and few tricks are better suited to provoking it than the use of chords and melodic lines that dodge the usual musical logic.

Back in rock territory, a fair number of bands ride the exoticism of Middle Eastern harmonies, whether for reasons of cultural identity (Altın Gün and Al-Qasar feature musicians of Turkish and Moroccan descent respectively), or out of a spiritual — and downright obsessive — interest in the belief systems of the Islamic world (as with the chameleonic Secret Chiefs 3, led by former Mr. Bungle member Trey Spruance).

The progressive djent of Cryptic Ruse leads us to the last sizeable contingent on the compilation, the metal crowd. In this field the pioneering project goes by the name Jute Gyte, responsible for a thoroughly uncompromising black metal that effectively (if not all that inventively) exploits the chaotic-evil potential of unconventional tunings. On a different tack are Sean Hayward's Untu, who pursue a — rather successful — fusion of doom sonorities and Javanese gamelan.

There would be plenty of other names worth mentioning, and some would definitely have deserved a spot on the playlist - if only their music were available on Spotify. A quick rundown will give the more curious readers some leads to explore on their own. Elaine Walker and Stephen Weigel are two central figures in the scene, authors of some of the most fun and varied music in the field. Walker has been active since the late Eighties, holds a master's degree in music technology and has experience working at NASA, and has released music both under her own name and with her spacetronic project Zia. Weigel, on the other hand, has a background in composition and media production, and besides writing and performing pieces for guitar and microtonal keyboards, he has put together a vast repertoire of xenharmonic covers of well-known songs (spiced up with wonderfully geek videos). He now runs the Now and Xen podcast, and his guitar can also be heard on a track by another successful xeno-pop project not available on Spotify: James Mulvale's FastFast.

Also missing from streaming platforms is the tireless electronic experimenter Wendy Carlos, who as early as 1986, with the kaleidoscopic "Beauty In The Beast", was already exploring xenharmony through slendro and pelog - tunings built on the harmonic series (extending just intonation) - and two scales of her own invention not based on the octave, dubbed alpha and beta. Like Carlos, many other trans people will find in xenharmony a field of artistic expression particularly suited to their sensibility, and more than one name in this playlist confirms this easily understandable elective affinity.

To close out the selection, two more names of undeniable fame. Both the recent Nine Inch Nails and YouTuber/wunderkind Jacob Collier have tried their hand at microtonality, with remarkable melodic skill. The creeping line of "Your New Normal" is one of the many xenharmonic excursions on the "Ghosts" series, contributing piano and synth pads to build a mysterious, unstable atmosphere. "In The Bleak Midwinter", on the other hand, is an a cappella rearrangement of a Christmas carol set to music by Harold Drake in 1911: between 4:15 and 4:30, it features a modulation (a gradual key change) from E major to G𝄲 major (a quarter tone above the ordinary G). The transition is so smooth it doesn't even disrupt the cloying sweetness of the recording!

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22/01/2026