A quarter tone (play (help·info)) is a pitch halfway between the usual notes of a chromatic scale or an interval about half as wide (aurally, or logarithmically) as a semitone, which itself is half a whole tone.

Trumpet with 3 normal valves and a quartering on the extension valve (right)

Quarter tones, or the quarter-tone scale (24 equal temperament), was proposed by 19th-century music theorists Heinrich Richter in 1823^[1] and Mikha'il Mishaqah about 1840.^[2]Composers who have written music using this scale include: Pierre Boulez, Julián Carrillo, Mildred Couper, George Enescu, Alberto Ginastera, Gérard Grisey, Alois Hába, Ljubica Marić, Charles Ives, Tristan Murail, Krzysztof Penderecki, Giacinto Scelsi, Ammar El Sherei, Karlheinz Stockhausen, Tui St. George Tucker, Ivan Alexandrovich Wyschnegradsky, and Iannis Xenakis. (See List of quarter tone pieces.)

Types of quarter tones[edit]

Composer Charles Ives chose the four-note chord above (C–D–G–A) as good possibility for a "fundamental" chord in the quarter-tone scale, akin not to the tonic but to the major chord of traditional tonality.^[3]Play chord (help·info) or Play scale (help·info)

The term quarter tone can refer to a number of different intervals, all very close in size. For example, some 17th- and 18th-century theorists used the term to describe the distance between a sharp and enharmonically distinct flat in mean-tone temperaments (e.g., D♯–E♭).^[1] In the quarter-tone scale, also called 24 tone equal temperament (24-TET), the quarter tone is 50 cents, or a frequency ratio of ²⁴√2 or approximately 1.0293, and divides the octave into 24 equal steps (equal temperament). In this scale the quarter tone is the smallest step. A semitone is thus made of two steps, and three steps make a three-quarter tone play (help·info) or neutral second, half of a minor third. The 8-TET scale is composed of three-quarter tones (Play (help·info)).

In just intonation the quarter tone can be represented by the septimal quarter tone, 36:35 (48.77 cents), or by the undecimal quarter tone, 33:32 (53.27 cents), approximately half the semitone of 16:15 or 25:24. The ratio of 36:35 is only 1.23 cents narrower than a 24-TET quarter tone. This just ratio is also the difference between a minor third (6:5) and septimal minor third (7:6).

Quarter tones and intervals close to them also occur in a number of other equally tempered tuning systems. 22-TET contains an interval of 54.55 cents, slightly wider than a quarter-tone, whereas 53-TET has an interval of 45.28 cents, slightly smaller. 72-TET also has equally tempered quarter-tones, and indeed contains three quarter-tone scales, since 72 is divisible by 24. The smallest interval in 31 equal temperament (the "diesis" of 38.71 cents) is half a chromatic semitone, one-third of a diatonic semitone and one-fifth of a whole tone, so it may function as a quarter tone, a fifth-tone or a sixth-tone.

Composer Ben Johnston, to accommodate the just septimal quarter tone, uses a small "7" () as an accidental to indicate a note is lowered 49 cents, or an upside down "7" () to indicate a note is raised 49 cents,^[4] or a ratio of 36:35.^[5] Johnston uses an upward and downward arrow to indicate a note is raised or lowered by a ratio of 33:32, or 53 cents.^[5]

Playing quarter tones on musical instruments[edit]

Quarter tone clarinet by Fritz Schüller

Any tunable musical instrument can be used to perform quarter tones, if two players and two identical instruments, with one tuned a quarter tone higher, are used. As this requires neither a special instrument nor special techniques, much quarter toned music is written for pairs of pianos, violins, harps, etc. The retuning of the instrument, and then returning it to its former pitch, is easy for violins, harder for harps, and slow and relatively expensive for pianos.

The following deals with the ability of single instruments to produce quarter tones. In Western instruments, this means "in addition to the usual 12-tone system".

Because many musical instruments manufactured today (2018) are designed for the 12-tone scale, not all are usable for playing quarter tones. Sometimes special playing techniques must be used.

Conventional musical instruments that cannot play quarter tones (except by using special techniques—see below) include:

• Most standard or unmodified non-electronic keyboard instruments, such as pianos, organs, and accordions
  


• 
  Fretted string instruments such as guitars, bass guitars, and ukuleles (though on these it is possible to play quarter tones by pitch-bending, with special tunings, or with customized necks)


• 
  Pitched percussion instruments, if standard techniques are used, and if the instruments are not tunable


• Western wind instruments that use keys or valves
  
  • 
    Woodwind instruments, such as clarinets, saxophones, flutes, and oboes (though with many of these, it is still possible using non-standard techniques such as special fingerings or by the player manipulating their embouchure, to play at least some quarter tones, if not a whole scale)
  
  
  • Valved brass instruments (trumpet, tuba) (though, as with woodwinds, embouchure manipulation, as well as harmonic tones that fall closer to quarter-tones than half-tones, make quarter-tone scales possible; the horn technique of adjusting pitch with the right hand in the bell makes this instrument an exception)
  
  

Conventional musical instruments that can play quarter tones include

• Electronic instruments:
  
  • 
    Synthesizers, using either special keyboard controllers or continuous-pitch controllers such as fingerboard controllers, or when controlled by a sequencer capable of outputting quarter-tone control signals.
  
  
  • 
    Theremins and other continuously pitched instruments
    
  
  


• Fretless string instruments, such as the violin family, fretless guitars, fretless electric basses, ouds, and members of the huqin family of instruments.


• String instruments with movable frets (such as the sitar)


• Specially fretted string instruments (such as the Turkish bağlama).


• Fretted string instruments specially tuned to quarter tones


• Pedal steel guitar


• Wind instruments whose main means of tone-control is a slide, such as trombones, the tromboon invented by P. D. Q. Bach, the slide trumpet and the slide whistle
  


• Specially keyed woodwind instruments. A quarter tone clarinet was built by Fritz Schüller (1883–1977) of Markneukirchen, and a quarter tone mechanism for flutes by Eva Kingma.


• Valved brass instruments with extra, quarter-tone valves, and natural brass instruments that play through the 11th and 13th partials of the harmonic series
  


• Kazoo


• 
  Pitched percussion instruments, when tuning permits (e.g., timpani), or using special techniques

Other instruments can be used to play quarter tones when using audio signal processing effects such as pitch shifting.

Quarter-tone pianos have been built, which consist essentially of two pianos with two keyboards stacked one above the other in a single case, one tuned a quarter tone higher than the other.^{[citation needed]}

Music of the Middle East[edit]

Many Persian dastgah and Arabic maqamat contain intervals of three-quarter tone size; a short list of these follows.^[6]

1. 
   Bayati (بیاتی): D E F G A B♭ C D
   

   
   

   
   



2. 
   Rast (راست):
   

   C D E F G A B C (ascending)

   
   

   C B♭ A G F E D C (descending)

   
   

   
   

   
   

   
   



3. 
   Saba (صبا): D E F G♭ A B♭ C D
   

   
   

   
   



4. 
   Sigah (سه گاه): E F G A B C D E
   

   
   

   
   



5. 
   ‘Ajam (عجم)


6. Hoseyni

The Islamic philosopher and scientist Al-Farabi described a number of intervals in his work in music, including a number of quarter tones.

Assyrian/Syriac Church Music Scale:^[7]

1. Qadmoyo (Bayati)


2. Trayono (Hussayni)


3. Tlithoyo (Segah)


4. Rbiʿoyo (Rast)


5. Hmishoyo


6. Shtithoyo (ʿAjam)


7. Shbiʿoyo


8. Tminoyo

Quarter tone scale[edit]

Known as gadwal in Arabic,^[8] the quarter tone scale was developed in the Middle East in the eighteenth century and many of the first detailed writings in the nineteenth century Syria describe the scale as being of 24 equal tones.^[9] The invention of the scale is attributed to Mikhail Mishaqa whose work Essay on the Art of Music for the Emir Shihāb (al-Risāla al-shihābiyya fi 'l-ṣināʿa al-mūsīqiyya) is devoted to the topic but also makes clear his teacher Sheikh Muhammad al-Attar (1764–1828) was one of many already familiar with the concept.^[10]

c1 cih cis cisih d dih dis disih e eih f fih fis fisih g gih gis gisih a aih ais aisih b bih bar "
"/>

The quarter tone scale may be primarily a theoretical construct in Arabic music. The quarter tone gives musicians a "conceptual map" they can use to discuss and compare intervals by number of quarter tones, and this may be one of the reasons it accompanies a renewed interest in theory, with instruction in music theory a mainstream requirement since that period.^[9]

Previously, pitches of a mode were chosen from a scale consisting of seventeen tones, developed by Safi al-Din al-Urmawi in the thirteenth century.^[10]

Composer Charles Ives chose the chord C–D–F–G–B♭ as good possibility for a "secondary" chord in the quarter-tone scale, akin to the minor chord of traditional tonality. He considered that it may be built upon any degree of the quarter tone scale^[3] Here is the secondary "minor" and its "first inversion":

In popular music[edit]

The Japanese multi-instrumentalist and experimental musical instrument builder Yuichi Onoue developed a 24-TET quarter tone tuning on his guitar.^[11] Several quarter-tone albums have been recorded by Jute Gyte, a one-man avantgarde black metal band from Missouri, USA^[12][13]. Another quartertone metal album was issued by the Swedish band Massive Audio Nerve^[14]. Australian psychedelic rock band King Gizzard & the Lizard Wizard's album Flying Microtonal Banana heavily emphasize quarter-tones.

Ancient Greek tetrachords[edit]

Greek Dorian enharmonic genus: two disjunct tetrachords each of a quarter tone, quarter tone, and major third. Play (help·info)

The enharmonic genus of the Greek tetrachord consisted of a ditone or an approximate major third, and a semitone, which was divided into two microtones. Aristoxenos, Didymos and others presented the semitone as being divided into two approximate quarter tone intervals of about the same size, while other ancient Greek theorists described the microtones resulting from dividing the semitone of the enharmonic genus as unequal in size (i.e., one smaller than a quarter tone and one larger).^[15][16]

Interval size in equal temperament[edit]

Here are the sizes of some common intervals in a 24-note equally tempered scale, with the interval names proposed by Alois Hába (neutral third, etc.) and Ivan Wyschnegradsky (major fourth, etc.):

interval name	size (steps)	size (cents)	midi	just ratio	just (cents)	midi	error (cents)
octave	24	1200	play (help·info)	2:1	1200.00	play (help·info)	+00.00
semidiminished octave	23	1150	play (help·info)	35:18	1151.23	play (help·info)	−01.23
supermajor seventh	23	1150	play (help·info)	27:14	1137.04	play (help·info)	+12.96
major seventh	22	1100	play (help·info)	15:80	1088.27	play (help·info)	+11.73
neutral seventh, major tone	21	1050	play (help·info)	11:60	1049.36	play (help·info)	+00.64
neutral seventh, minor tone	21	1050	play (help·info)	20:11	1035.00	play (help·info)	+15.00
large just minor seventh	20	1000	play (help·info)	9:5	1017.60	play (help·info)	−17.60
small just minor seventh	20	1000	play (help·info)	16:90	0996.09	play (help·info)	+03.91
supermajor sixth/subminor seventh	19	0950	play (help·info)	7:4	0968.83	play (help·info)	−18.83
major sixth	18	0900	play (help·info)	5:3	0884.36	play (help·info)	+15.64
neutral sixth	17	0850	play (help·info)	18:11	0852.59	play (help·info)	−02.59
minor sixth	16	0800	play (help·info)	8:5	0813.69	play (help·info)	−13.69
subminor sixth	15	0750	play (help·info)	14:90	0764.92	play (help·info)	−14.92
perfect fifth	14	0700	play (help·info)	3:2	0701.96	play (help·info)	−01.96
minor fifth	13	0650	play (help·info)	16:11	0648.68	play (help·info)	+01.32
lesser septimal tritone	12	0600	play (help·info)	7:5	0582.51	play (help·info)	+17.49
major fourth	11	0550	play (help·info)	11:80	0551.32	play (help·info)	−01.32
perfect fourth	10	0500	play (help·info)	4:3	0498.04	play (help·info)	+01.96
tridecimal major third	09	0450	play (help·info)	13:10	0454.21	play (help·info)	−04.21
septimal major third	09	0450	play (help·info)	9:7	0435.08	play (help·info)	+14.92
major third	08	0400	play (help·info)	5:4	0386.31	play (help·info)	+13.69
undecimal neutral third	07	0350	play (help·info)	11:90	0347.41	play (help·info)	+02.59
minor third	06	0300	play (help·info)	6:5	0315.64	play (help·info)	−15.64
septimal minor third	05	0250	play (help·info)	7:6	0266.87	play (help·info)	−16.87
tridecimal five-quarter tone	05	0250	play (help·info)	15:13	0247.74	play (help·info)	+02.26
septimal whole tone	05	0250	play (help·info)	8:7	0231.17	play (help·info)	+18.83
major second, major tone	04	0200	play (help·info)	9:8	0203.91	play (help·info)	−03.91
major second, minor tone	04	0200	play (help·info)	10:90	0182.40	play (help·info)	+17.60
neutral second, greater undecimal	03	0150	play (help·info)	11:10	0165.00	play (help·info)	−15.00
neutral second, lesser undecimal	03	0150	play (help·info)	12:11	0150.64	play (help·info)	−00.64
15:14 semitone	02	0100	play (help·info)	15:14	0119.44	play (help·info)	−19.44
diatonic semitone, just	02	0100	play (help·info)	16:15	0111.73	play (help·info)	−11.73
21:20 semitone	02	0100	play (help·info)	21:20	0084.47	play (help·info)	+15.53
28:27 semitone	01	0050	play (help·info)	28:27	0062.96	play (help·info)	−12.96
33:32 semitone	01	0050	play (help·info)	33:32	0053.27	play (help·info)	−3.27
unison	00	0000	play (help·info)	1:1	0000.00	play (help·info)	+00.00

Moving from 12-TET to 24-TET allows the better approximation of a number of intervals. Intervals matched particularly closely include the neutral second, neutral third, and (11:8) ratio, or the 11th harmonic. The septimal minor third and septimal major third are approximated rather poorly; the (13:10) and (15:13) ratios, involving the 13th harmonic, are matched very closely. Overall, 24-TET can be viewed as matching the 11th and 13th harmonics more closely than the 7th.

See also[edit]

• Musical temperament


• List of quarter tone pieces


• List of meantone intervals

References[edit]

Further reading[edit]

• Bartolozzi, Bruno (1967). New Sounds for Woodwind. London, New York: Oxford University Press.


• Bousted, Donald (2002). "Microtonality, the Recorder and the Quarter-Tone Recorder Manual". The Recorder Magazine 22, no. 3 (Fall): 99–102.


• Bousted, Donald (2005). "Next Step Quarter-Tone Resources: Melody". The Recorder Magazine 25, no. 3 (Fall): 88–91.


• Caravan, Ronald R. (1979). Preliminary Exercises and Etudes in Contemporary Techniques for Clarinet: Introductory Material for the Study of Multiphonics, Quarter Tones, and Timbre Variation. [Oswego, N.Y.]: Ethos Publications.


• Ellis, Don (1975). Quarter Tones: A Text with Musical Examples, Exercises and Etudes. Plainview, N.Y.: Harold Branch Pub. Co.


• MacDonald, John (1822). A Treatise on the Harmonic System Arising from the Vibrations of the Aliquot Divisions of Strings According to the Gradual Progress of the Notes from the Middle, to the Remote Extremes: Explaining Simply, by Curved Delineations, the Manner in Which the Harmonic Tones, Half and Quarter Notes, Are Generated and Produced on Every Corresponding Part of the String; and under a Copious Explanatory Description Illustrated by Musical and Appropriate Plates, Giving an Easy and Familiar Adaptation of the Whole to the Purposes of Composition and Instrumental Music, and More Particularly, to the Practice of the Violin, Tenor, Violoncello and Double Bass, on All the Strings, and in Every Compass of These Instruments, by Every Practical Mode of Execution; with Some Musical Animadversions Introductory of the General Subject, Briefly Alluding to the Rise and Progress of Music, and to the Corrections of Temperament: and Stating Various Improvements of Instruments, Experimentally Ascertained: Concluding with an Application or Two of the Principle of Musical Notes, to Purposes of Utility, and a Reference to Terms Less Generally Noticed. London: Printed for the Author, and Sold by T. Preston.


• Möllendorff, Willi, and Joe Monzo (2001). Music with Quarter-Tones: Experiences at the Bichromatic Harmonium. [United States]: J. Monzo.


• Rees, Carla (2007). "Eva Kingma and the Quarter-Tone Flute". Pan: The Flute Magazine 26, no. 4:23–29.


• Rewoldt, Todd (2000). "Altissimo Quarter-Tones for the Alto Saxophone". Saxophone Symposium 25:56–69.

External links[edit]

• "quarter-tone / 24-edo", TonalSoft.com.