Vowel category perception affected by microdurational variations

Vowel quality perception in quantity languages is considered to be unrelated to vowel duration since duration is used to realize quantity oppositions. To test the role of microdurational variations in vowel category perception in Estonian listening experiments with synthetic stimuli were carried out, involving five vowel pairs along the close-open axis. The results show that in the case of high-mid vowel pairs vowel openness correlates positively with stimulus duration; in mid-low vowel pairs no such correlation was found. The discrepancy in the results is explained by the hypothesis that in case of shorter perceptual distances (high-mid area of vowel space) intrinsic duration plays the role of a secondary feature to enhance perceptual contrast between vowels, whereas in case of mid-low oppositions perceptual distance is large enough to guarantee the necessary perceptual contrast by spectral features alone and vowel intrinsic duration as an additional cue is not needed.