What Is a Microtone? Musical Intervals Explained

This lesson compares three musical tuning systems: Pythagorean tuning (based on 4:3 and 3:2 ratios, creating dissonant thirds), Just Intonation (adding 5:4 and 6:5 ratios for pure thirds but limiting modulation), and Equal Temperament (dividing the octave into 12 equal semitones of 100 cents each, enabling modulation across all keys). While Equal Temperament sacrifices pure interval ratios (fifths are 700 cents vs. 702 cents in pure systems), it provides the practical advantage of consistent sound across all tonalities, making it the standard for modern instruments despite the subtle imperfections that composers like Scriabin noted.

Three alternative systems address Pythagorean's limitations. Just intonation (純正律) uses three rules: octave = 2:1, perfect fifth = 3:2, major third = 5:4. Major triads use ratios 4:5:6, creating pure harmonies. However, it cannot handle all keys equally. Meantone temperament (中全音律) narrows the perfect fifth by 1/4 of the syntonic comma, allowing 4 fifths to produce a pure major third. This allows 6 keys while maintaining good thirds. Equal temperament (平均律) divides the octave into 12 equal semitones (2^(1/12) per semitone), allowing any key without retuning but sacrificing interval purity. Each system represents a trade-off between harmonic purity and key flexibility.

This section explains the fundamental concepts of musical temperaments. Equal temperament uses A440 (440 Hz) as a reference to calculate all 12 notes in an octave, allowing musicians to play in any key with all chords sounding acceptable. Just intonation uses natural whole number ratios to create perfectly in-tune intervals but cannot support key modulation. Neither system is objectively right or wrong—they serve different musical purposes. Critically, achieving perfect intonation across all keys on a 12-note-per-octave fretted instrument is mathematically impossible.

Modern instruments typically use equal temperament tuning where octaves are divided into equal steps, resulting in complex frequency ratios between notes. Alternative just intonation systems keep frequency ratios simple, such as tuning a perfect fifth to an exact 3:2 ratio relative to the root note. These simpler ratios occur naturally in physical phenomena like vibrating strings, and some argue they produce purer, more harmonious sounds that resonate more naturally with human perception.

In 24-TET tuning, the 12 additional notes beyond the standard Western chromatic scale are called half sharps or half flats. These are indicated with special symbols. A half sharp raises a note by a quarter tone (e.g., D half sharp is a quarter tone sharper than regular D). A half flat lowers a note by a quarter tone (e.g., E half flat is a quarter tone flatter than regular E). When played in sequence, these microtonal accidentals create an ultra-chromatic scale where each adjacent note is only one quarter tone apart, such as D half sharp → E flat → E half flat → E natural.

Microtonal music uses tuning systems with more than 12 notes per octave, requiring specialized notation systems such as the mainstream quartertone notation (using half-sharp and half-flat accidentals for 24-edo), Sagittal notation for complex tunings, and traditional Persian accidentals (K for quarter-flat, S for quarter-sharp) to accurately represent pitches between standard semitones.

The video explains specialized notation systems for representing microtonal music. Natural notes (white piano keys) are shown in black, while sharp notes (black piano keys) are shown in green. Quarter tones have two different symbols: a flat symbol (B) for quarter tone below, and a sharp symbol with a line for quarter tone above. For non-musicians, blue indicates quarter tone above and red indicates quarter tone below. This notation system allows representation of the 18-20 notes used by Nazca instruments, which cannot be fully represented on a standard piano.

Microtonal notation in woodwinds uses specific symbols to indicate quarter tones. A regular flat symbol indicates one quarter tone lower, while three lines indicate three quarter tones lower. Similarly, regular sharps indicate one quarter tone higher, and three lines indicate three quarter tones higher. These symbols are standardized today. For microtonal passages, it is important to provide fingering suggestions since standard fingerings may not produce ideal results. Players can find appropriate fingerings in specialized books about special techniques for each instrument.

Microtonal music uses specialized notation symbols including backwards flats and three-quarters sharps within the standard five-line staff system. The Secret Trio explains how their compositions employ ancient microtonal modal systems combined with unusual time signatures, creating complex musical textures. They discuss translating these compositions to diverse ensembles from solo performances to symphonic orchestras, noting that contemporary classical music has developed standardized notation for microtones. However, practical challenges arise when adapting complex pieces to large ensembles within limited rehearsal time, requiring simplification and adaptation strategies.

Ben Johnston, a pioneering microtonal composer who studied with Harry Partch in 1949, composed this 1998 song cycle 'The Tavern' using his adapted guitar with movable frets that allows 15 notes per octave. The piece sets Rumi's Sufi poetry, which uses the metaphor of wine and taverns to represent spiritual enlightenment and the soul's journey toward divine union, exploring themes of transcendence beyond ordinary perception.

Microtonality is not a modern invention but has been used for centuries in various musical traditions. Arabic and Indian traditional music have employed microtonal intervals for centuries. In the Renaissance, composer Nicola Vicentino invented the Archicembalo, a microtonal keyboard instrument. In the 20th century, composer Harry Partch constructed entire instruments specifically for playing microtonal music. The reason modern audiences find microtonal music strange is that our ears have been conditioned by 100 years of radio, Spotify, and pop music that only uses the 12-note system.

Harry Partch's 'US Highball' is a 1946 microtonal composition that captures the experiences of railroad workers through innovative musical scales, recorded at Warren Gilson's home in Madison, Wisconsin, and pressed in a limited edition of 100 copies.

The opening movement of Ben Johnston’s String Quartet No. 10 follows a textbook sonata structure—exposition, development, recapitulation—with two themes: the first in microtonally extended G minor, the second in B-flat major, both returning in the tonic during recapitulation. Despite its classical form, the music features polyrhythms: violin 1 and cello imply 3-beat patterns out of phase with inner voices in syncopated 4. Harmony is tonal but extended microtonally, with notes “between the cracks” suggesting spectral independence. The slow movement is a fugue in 13-limit harmony centered on extended D minor. The scherzo and trio employ a complex rhythmic structure where each instrument divides the measure into 4, 5, 6, and 7 beats respectively, aligning only on downbeats, creating a Nancarrow-esque rhythmic tension. The finale functions as a “music history essay,” beginning with a Renaissance-style dance in 6/8, featuring viola col legno battuto, evoking Cowell and Harrison. A 4/4 middle section shifts harmonic language while preserving 5-limit just tuning with occasional 7-limit intervals. The movement then unexpectedly introduces “Danny Boy,” harmonized with extended 7th, 11th, and 13th partials, evoking jazz through a walking bass line. The entire finale is revealed as a set of variations on “Danny Boy,” with the opening theme being its strict inversion. The piece concludes with players sustaining open strings (D, G, C, C) while performing a glissando of harmonics, reducing music to pure tone and revealing its spectral structure—symbolizing the end of musical history and the emergence of acoustic essence.

Harry Partch's 'Castor & Pollux' (1952) demonstrates his unique approach to microtonal composition by using three separate instrumental groups (each with identical measure patterns but different rhythms) that combine simultaneously in the final 'Delivery' section, creating a single unified composition from multiple independent parts—a technique he called 'triple exposure' where three different compositions become one through simultaneous performance.

Modern digital audio software typically uses the 12-tone equal temperament scale by default. To accurately reproduce the sounds of microtonal instruments like the chipi, software must support custom tuning systems. This requires implementing microtuning features that allow users to load scale files (such as those in Scala format) and apply them to sampled instruments. Once implemented, users can drag scale files onto the sampler window to make notes play according to the specified microtonal system rather than the standard chromatic scale.

Scale Workshop enables users to implement custom microtonal tunings across major digital audio workstations and synthesizers. The application supports exporting to multiple formats including Anna Mark Tune files for Omnisphere, Native Instruments, and Serum; Scala files for Arturia synths and GPO 4; Carla files for open-source synths like ZynAddSubFX and Absynth; Max/MSP text files for Max/MSP and Pure Data environments; and Kontakt scripts for Native Instruments Kontakt instruments. This comprehensive compatibility allows musicians to experiment with microtonal tunings across their entire software synthesizer collection.

The Destiny X synthesizer's SD multisample mode supports microtonal tunings using Scala files, which are placed on the microSD card in designated folders (SEL for scales, KVM for keyboard maps). Users can select from default scales like equal temperament or the R & Johnson 710 seven-tone scale, and must match the keyboard map to the scale to avoid mismatch warnings. Custom Scala files can be generated online and exported to enable microtonal tuning on the sample player.

The video provides a tutorial on microtuning various digital audio software used by music producers and composers. It begins with an introduction to Scaleworkshop, a web-based tool available at plainsound.org, likely used for creating or exploring microtonal scales. The video then guides viewers through applying microtuning in specific plugins: Pigments, Serum, Omnisphere, Kontakt, Pianoteq, LoungeLizard, and Harmor. Each section is timestamped, indicating step-by-step demonstrations for each software. The video explicitly references tuning files, suggesting users load custom tuning data (e.g., .tun or .scf files) into these plugins to alter pitch relationships beyond standard 12-TET tuning. The tutorial covers practical implementation rather than theoretical foundations, focusing on workflow within popular synthesizers and samplers. The video concludes with general tips for microtuning, likely addressing common pitfalls or best practices. The content is structured for users seeking to implement microtonal music in their productions using industry-standard tools. No theoretical background on microtonality or scale theory is provided. The focus remains strictly on software-specific procedures.