Acoustic Vowel Reduction in Creek: Effects of Distinctive Length and Position in the Word

Eight speakers (4 male and 4 female) of the Muskogee dialect of Creek pronounced a set of words illustrating the vowels and diphthongs of Creek. These recordings were analyzed acoustically and data on vowel duration and vowel formant frequencies are presented in this paper. The ratio of the durations of dictinctively long and short vowels was 1.8. This ratio showed a sex difference, being larger for female speakers than it was for male speakers. Final lengthening was also observed: both distinctively long and short vowels were longer in word-final position than in word-initial position. The vowel formant data showed two additive, orthogonal phonetic vowel reduction processes: short vowel centralization and positional reduction. Short vowel centralization has been found in many languages. Distinctively long vowels in Creek tended to be more peripheral in the acoustic vowel space than were the distinctively short vowels. Positional reduction is also evident in these data: vowels in word-final position were reduced relative to vowels in word-initial position. Short vowel centralization was preserved in both positions in the word. Positional reduction has been documented in several languages, and these results from Creek lend support to the hypothesis that it is a general property of speech production. The results of this acoustic-phonetic study, the first such study of Creek, are discussed in light of cross-linguistic phonetic trends.