Microtones and Non-Western Scales: Twelve Notes Is a Choice, Not a Law
The piano's twelve keys per octave feel like a fact of nature. They are a historically recent, specific compromise.
Short answer: the twelve-note equal-tempered scale most Western-trained ears grew up on is one particular, historically recent solution to the tuning problem, covered in full on our equal temperament page, not a law of acoustics. Many musical traditions divide the octave differently, or use pitches that fall between the piano's keys entirely, deliberately and systematically. Grove Music Online defines these in-between pitches as microtones and treats them as a real, structured category rather than as mistakes (Grove, "Microtone," 2001). Gamelan ensembles, Arabic and Turkish maqam systems, and the Indian classical shruti framework are three well-documented examples, each with its own internal logic. And the ear is not simply born knowing what to do with any of this: controlled studies find that learning an unfamiliar, well-formed microtonal scale is measurably harder and slower than learning a scale built from familiar twelve-tone materials, meaning microtonal hearing is a real, trainable skill with its own learning curve (Leung and Dean, 2018).
What "microtone" actually means
A microtone is any pitch that does not fall on the standard twelve-tone equal-temperament grid, the black and white keys of a piano. It is not, by definition, an out-of-tune note; it is an interval that a given tradition uses on purpose, with its own name and its own function, the same way a major third has a name and a function in Western harmony. Several traditions build entire scale systems from steps smaller or differently spaced than the Western semitone. Indonesian gamelan uses two distinct tuning systems, slendro, with roughly five unequal steps per octave, and pelog, with roughly seven unequal steps (Grove, "Gamelan," 2001). Arabic, Turkish, and Persian maqam and makam systems are commonly analysed using scales with intervals around a quarter-tone, roughly half the size of a Western semitone, positioned between the pitches a piano can produce. Indian classical music theory, both Hindustani and Carnatic, is traditionally described using a shruti framework that recognises a substantially finer grid of possible pitch positions within the octave than twelve, a framework still used as the analytical basis for computational work on Indian classical music today (Singh, Kumar and Biswas, 2021).
Gamelan tuning: not just "not equal temperament"
It would be easy to describe gamelan tuning as simply an alternative to equal temperament and stop there, but that undersells what actually happens. Each gamelan ensemble is tuned individually, instrument by instrument, by ear, as a complete set. Because of that, no two gamelan ensembles share exactly the same tuning, even when both are nominally playing the same slendro or pelog system (Grove, "Gamelan," 2001). That is treated as a feature, not a flaw: each ensemble's specific tuning is part of its individual sonic identity, the opposite of the standardised, interchangeable approach behind a piano built to a fixed factory specification and a shared A440 reference.
| System | Roughly how many steps per octave | Are the steps equal | Tradition |
|---|---|---|---|
| 12-tone equal temperament | 12 | yes, by design | Western common-practice music, most popular music, piano, guitar |
| Slendro | around 5 | no, and it varies by ensemble | Javanese and Balinese gamelan |
| Pelog | around 7 | no, and it varies by ensemble | Javanese and Balinese gamelan |
| Maqam / makam systems | often analysed with quarter-tone-sized steps, roughly 24 per octave | no, context and mode dependent | Arabic, Turkish, and Persian classical and folk music |
| Shruti framework | traditionally 22 recognised pitch positions | no, unequal | Indian classical music theory, Hindustani and Carnatic |
Can untrained ears learn a new microtonal scale?
Two related studies tested this directly, rather than assuming an answer. Leung and Dean had listeners try to learn an unfamiliar, well-formed microtonal scale and measured how the size of its pitch intervals and how familiar its underlying structure was affected learning speed, finding both mattered and that rapid, easy learning was not the default outcome for an unfamiliar system (Leung and Dean, 2018, Journal of New Music Research). A companion study framed the same finding around difficulty specifically: learning an unfamiliar microtonal tuning quickly is genuinely hard, and that difficulty tracks measurable properties of the scale itself rather than being a fixed, uniform barrier every listener faces equally (Leung and Dean, 2018, Psychomusicology). Together, the two studies support a specific and useful conclusion: microtonal hearing is not something an ear either has or lacks. It is a skill with a real learning curve, shaped by exposure and by the structure of the specific system being learned, the same way any other kind of categorical pitch learning is.
Why this matters for ear training generally
Standard interval-recognition training, covered on our interval ear training guide, teaches the boundaries of the Western twelve-tone categories precisely, and that precision has a cost. The same categorical hearing that makes a trained listener fast and confident at naming "major third" can make a genuinely foreign, in-between pitch register simply as "out of tune," when it is neither out of tune nor a mistake, it is a different system's note, following different rules. Recognising that twelve-tone equal temperament is one specific, useful choice among several, not the only correct grid, is itself part of developing a more accurate ear, not a separate topic from it.
What our games do here, honestly
None of Hearkle's eleven games teaches any specific non-Western tuning system, gamelan, maqam, or shruti included; that would need its own dedicated content, tuned to that system's actual pitches, which we do not have. What the games can train is the underlying raw skill microtonal listening calls on: locating a pitch that does not sit on your familiar reference grid. Heartween asks you to find the pitch exactly halfway between two reference tones, which is precisely that kind of in-between pitch judgement, even though it works within our own tuning reference rather than any specific microtonal system.
Can you find the pitch in between? Microtonal listening starts with hearing a pitch that is not on your familiar grid. Heartween trains exactly that: locating the pitch exactly halfway between two tones.
Keep reading
- Equal temperament vs just intonation: why the twelve-tone grid itself is a compromise, even within Western tuning.
- Consonance and dissonance: the acoustic background microtonal intervals are judged against.
- What is an octave?: the one interval every tuning system in this article agrees on.
- Interval ear training: a beginner's guide: the twelve-tone category training that microtonal listening has to work around.
Frequently asked questions
What is a microtone?
Any pitch that does not fall on the standard twelve-tone equal-temperament grid used by a piano or a guitar's frets. Microtones are not mistakes; many musical traditions use specific, named in-between pitches deliberately and systematically, with their own function within that tradition's scale system (Grove, "Microtone," 2001).
Is a microtone the same as an out-of-tune note?
No. An out-of-tune note is a deviation from a target the performer was trying to hit. A microtone is the target itself, in traditions that use pitches outside the twelve-tone grid on purpose, the same way a major third is the deliberate target in Western harmony rather than a deviation from something else.
How many notes does gamelan music use?
It depends on the tuning system and the individual ensemble. Gamelan uses two main systems, slendro, with roughly five unequal steps per octave, and pelog, with roughly seven, and because each gamelan ensemble is tuned by ear as its own complete set, no two ensembles share exactly the same tuning even within the same system (Grove, "Gamelan," 2001).
Can I train my ear to hear microtones?
Yes, but expect it to take real, deliberate practice rather than happening automatically. Controlled studies found that learning an unfamiliar, well-formed microtonal scale is measurably harder and slower than learning something built from familiar twelve-tone material, and that the difficulty tracks specific, measurable properties of the scale rather than being a fixed wall (Leung and Dean, 2018).
Why does 12-tone equal temperament feel "normal" if it is just one choice among several?
Because it is the system most Western-trained listeners have been exposed to for their entire lives, and categorical pitch perception is shaped heavily by exposure. That familiarity is real and useful within the tradition it comes from; it is a product of exposure and training, not evidence that the twelve-tone grid is the only correct or natural way to divide the octave.
Sources: Microtone and Gamelan, Grove Music Online, Oxford University Press; Leung and Dean (2018), Learning a well-formed microtonal scale: Pitch intervals and event frequencies, Journal of New Music Research 47(3); Leung and Dean (2018), The difficulty of learning microtonal tunings rapidly: The influence of pitch intervals and structural familiarity, Psychomusicology: Music, Mind, and Brain 28(1); Singh, Kumar and Biswas (2021), Swaragram: Shruti-Based Chromagram for Indian Classical Music, in Advances in Speech and Music Technology, Springer.