Vowel identification and vowel space characteristics

Acoustic characteristics of ten vowels produced by 45 men and 48 women from the Hillenbrand et al. (1995) study were correlated with identification accuracy. Global (mean f0, F1 and F2, duration, and amount of formant movement) and distinctive measures (vowel space area, mean distance among vowels, f0, F1 and F2 ranges, duration ratio between long and short vowels, and dynamic ratio between dynamic and static vowels) were used to predict identification scores. Global and distinctive measures accounted for less than one-fourth of variance in identification scores: vowel space area alone accounted for 9% to 12% of variance. Differences in vowel identification across talkers were largely due to poor identification of two spectrally similar vowel pairs /ae/-/eh/ and /uh/-/ah/. Results of acoustic analysis and goodness ratings for well-identified and poorly identified versions of these vowels will be presented. Preliminary analysis revealed that well-identified vowels differed from poorly identified tokens not only in static formant frequencies but also in duration and amount of formant movement over time. A talker’s ability to create distinctions among neighboring vowels is more important in determining vowel intelligibility than overall measures such as vowel space area.