Phonetic correlates of tongue root vowel contrasts in Maa

Maa, a Nilo-Saharan language, exhibits a cross-height vowel harmony system known as 'tongue root harmony'.The high and mid vowels participate in this system, but the low vowel does not. The Maa harmony system is briefly described, followed by an investigation into the phonetic properties of the vowels. Five Maa speakers were recorded producing 100 example words three times each. The [+ATR] vowels were found to have consistently lower first formant values and relatively less energy in the higher frequency regions than their [-ATR] counterparts. An investigation of the differences between the auditorily quite similar [-ATR] high and [+ATR] mid vowels revealed durational differences for the back vowels and much inter-speaker variation for the front vowels. Electroglot tographic data obtained from one speaker indicated a slightly less constricted glottis for [+ATR] than [-ATR] vowels. This phonation difference is not readily detectable auditorily in the current data, but has been reported previously for Maa. The results contribute to typological knowledge about the phonetics of tongue root vowel contrasts, as very little data is currently available for Nilo-Saharan languages. A possible origin of stronger voice quality distinctions common to other tongue root harmony languages is offered from the theory of Auditory Enhancement.