Uncovering the acoustic vowel space of a previously undescribed language: The vowels of Nambo.

This study presents the first acoustic description of the vowel space of a Papuan language-Nambo, spoken in southern Papua New Guinea-based on duration and first and second formant measurements from 19 adult male and female speakers across three age groups (young, middle-aged, senior). Phonemically, Nambo has six full vowels /i, e, æ, ɑ, o, u/ and a reduced vowel tentatively labeled /ə/. Unlike the full vowels, the quality of /ə/ showed great variation: seniors' and young females' realizations tended to be more open and retracted than those by young males, while middle-aged speakers' productions fell between these two variants.