Advanced tongue root, abbreviated ATR or +ATR, also called expanded, involves the expansion of the pharyngeal cavity by moving the base of the tongue forward and often lowering the larynx during the pronunciation of avowel. The lowering of the larynx sometimes adds a breathy quality to the vowel. Voicedstops such as can often involve non-contrastive tongue root advancement whose results can be seen occasionally in sound changes relating stop voicing and vowel frontness such as voicing stop consonants before front vowels in the Oghuz Turkic languages or in Adjarian's law: the fronting of vowels after voiced stops in certain dialects of Armenian. True uvular consonants appear to be incompatible with advanced tongue root, i.e. they are inherently . Combined with the above tendency for voiced stops to be , that motivates the extreme rarity of the voiced uvular stop compared to its voiceless counterpart. The International 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 vowels in a system of vowel harmony, which occurs commonly in large parts of West Africa. ATR vowels involve a certain tension in the tongue, often in the lips and jaw as well; the ear can often perceive this tension as a "brightness" compared to RTR vowels. Nonetheless, phoneticians do not refer to ATR vowels as tense vowels since the wordtense already has several meanings in European phonetics.
Retracted tongue root
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 as pharyngealized. 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. The diacritic for RTR in the International Phonetic Alphabet is the right tack,.
As mentioned above, many African languages, such as Maasai, have systems of vowel harmony based on tongue root position. That is illustrated here with the Fante dialect of Akan, which has fifteen vowels: five +ATR vowels, five −ATR vowels, and five nasal vowels. There are two harmonization rules that govern the vowels that may co-occur in a word:
All −ATR vowels become +ATR when followed by a peripheral +ATR vowel. That is, orthographic e ɛ a ɔ o become i e a o u before i u and sometimes before a.
As long as it does not conflict with the previous rule, the +ATR mid vowels become −ATR high vowels when preceded by a −ATR non-high vowel.
In the Twi language, the ±ATR distinction has merged in the low vowel and so is harmonically neutral, occurring with either set of vowels. In addition, the two vowels written e and o are often not distinguished and are approximately equivalent to European and, as reflected in the orthography; for such people, the second harmonization rule does not apply.
With advances in fiber-opticlaryngoscopy at the end of the twentieth century, new types of phonation were discovered that involve more of the larynx than just the glottis. One of the few languages studied thus far, the Togolese languageKabiyé, has a vocalic distinction that had been assumed to be one of tongue root. However, it turned out to be a phonation distinction of faucalized voice versus harsh voice. It is not yet clear whether that is characteristic of ±ATR distinctions in general.
