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, lowering the
larynx, and otherwise expanding the walls of the pharynx during the pronunciation of a vowel. This may result in +ATR vowels being longer than −ATR vowels. The lowering of the larynx sometimes adds a
breathy quality to the vowel.
Voiced stops such as 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 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 [−ATR]. Combined with the above tendency for voiced stops to be [+ATR], 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 (RTR) 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" (narrow
formants) compared to RTR vowels. Nonetheless, phoneticians do not refer to ATR vowels as
tense vowels since the word
tense already has several meanings in European phonetics. ==Retracted tongue root==