Inphonetics,advanced tongue root (ATR or+ATR), orexpanded pharynx, andretracted tongue root (RTR or−ATR) are contrasting states of thepharynx during thepronunciation ofvowels in some languages, especially inWest andEast Africa, but also inKazakh andMongolian. ATR vs RTR was once suggested to be the basis for the distinction betweentense and lax vowels inEuropean languages such asGerman, but Ladefoged and Maddieson have found that the tongue root position in Germanic languages is not an independent gesture.^[1]

Advanced tongue root, abbreviated ATR or +ATR, also calledexpanded,^[2] involves the expansion of thepharyngeal cavity by moving the base of the tongue forward, lowering thelarynx, and otherwise expanding the walls of the pharynx during the pronunciation of a vowel.^[3] This may result in +ATR vowels being longer than −ATR vowels. The lowering of the larynx sometimes adds abreathy quality to the vowel.

Voicedstops such as[b],[d],[ɡ] can often involve non-contrastive tongue root advancement. Results can be seen occasionally in sound changes relating stop voicing and vowel frontness, such as voicing stop consonants beforefront vowels in theOghuz Turkic languages; or inAdjarian's law (the fronting of vowels after voiced stops in certain dialects ofArmenian).^[4]

Trueuvular consonants appear to be incompatible with advanced tongue root, i.e. they are inherently [−ATR]. Combined with the above tendency for voiced stops to be [+ATR], that motivates the extreme rarity of thevoiced uvular stop[ɢ] compared to its voiceless counterpart[q].^[4]

TheInternational Phonetic Alphabet represents ATR with a "left tack"diacritic,[◌̘].

In languages in which they occur, advanced-tongue-root vowels very often contrast with retracted tongue root (RTR) vowels in a system ofvowel harmony, which occurs commonly in large parts of West Africa.^[5]

ATR vowels involve a certain tension in the tongue, often in thelips and jaw as well; the ear can often perceive this tension as a "brightness" (narrowformants) compared to RTR vowels^{[citation needed]}. Nonetheless, phoneticians do not refer to ATR vowels astense vowels since the wordtense already has several meanings in European phonetics.

Retracted tongue root, abbreviated RTR, is the retraction of the base of the tongue in the pharynx during the pronunciation of a vowel, the opposite articulation of advanced tongue root. This type of vowel has also been referred to aspharyngealized.^[6]

The neutral position of the tongue during the pronunciation of a vowel, contrasting with advanced tongue root and thus marked -ATR, is also sometimes referred to as retracted tongue root.^{[citation needed]}

The diacritic for RTR in theInternational Phonetic Alphabet is the right tack,[◌̙].

As mentioned above, many African languages, such asMaasai, have systems ofvowel harmony based on tongue root position. That is illustrated here with theFante dialect ofAkan, which has fifteen vowels: five +ATR vowels, five −ATR vowels, and fivenasal vowels.

Fante ±ATR vowels

Ortho- graphy	+ATR value	−ATR value	Approx. European equivalents
i	/i̘/		[i]
e	/e̘/	/i/	[e],[ɪ]
ɛ		/e/	[ɛ]
a	/a̘/	/a/	[æ],[ɑ]
ɔ		/o/	[ɔ]
o	/o̘/	/u/	[o],[ʊ]
u	/u̘/		[u]

There are two harmonization rules that govern the vowels that may co-occur in a word:

1. All −ATR vowels become +ATR when followed by a peripheral +ATR vowel (/i̘a̘u̘/). That is, orthographice ɛ a ɔ o becomei e a o u beforei u and sometimes beforea.
2. As long as it does not conflict with the previous rule, the +ATR mid vowels (/e̘o̘/) become −ATR high vowels (/iu/) when preceded by a −ATR non-high vowel (/eao/). (It is not reflected in the orthography; underlying and surface vowels are both spellede o.)

In theAsante dialect, the ±ATR distinction has merged in thelow vowel and so/a/ is harmonically neutral, occurring with either set of vowels. In addition, the two vowels writtene (/e̘/ and/i/) ando (/o̘/ and/u/) are often not distinguished and are approximately equivalent to European[e] and[o], as reflected in the orthography; for such people, the second harmonization rule does not apply.^[7]

With advances infiber-opticlaryngoscopy at the end of the twentieth century, new types ofphonation were discovered that involve more of thelarynx than just theglottis. One of the few languages studied thus far, theTogolese languageKabiyé, has a vocalic distinction that had been assumed to be one of tongue root. However, it turned out to be a phonation distinction offaucalized voice versusharsh voice.^[8]

It is not yet clear whether that is characteristic of ±ATR distinctions in general.

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• The back-vowel constraint, an effect of tongue-root retraction in some click consonants.

• Ladefoged, Peter; Maddieson, Ian (1996).The Sounds of the World's Languages. Oxford: Blackwell.

• Maasai Vowels, with audio examples of [+ATR] and [-ATR]

• Vowels

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