Effect of dynamic information of formants on discrimination of English vowels in consonantal contexts by Japanese listeners

This study examined how differently native speakers of Japanese discriminated between the American English vowels /e/ and /ae/ in /CVp/ syllables with 20 different initial consonants, and how the differing discrimination was related to the formant changes throughout the vowels in comparison with the Japanese vowels /e/ and /a/. A perceptual test and formant analyses of the English and Japanese vowels were conducted. The results showed that there were significant differences in discrimination across the consonantal contexts: the discrimination of /e/ was significantly poorer when the initial consonant was /dg/, /g/, /ch/, /m/ or /th/ (voiceless), and that of /ae/, when it was /sh/, /h/ or /t/. It was found that the poorer discrimination was more related to the smaller formant ratios (F2/F1) and the higher F1 frequency in the latter part of /e/, and to the larger formant ratios and the lower F1 frequency in the latter part of /ae/. The changing of formant patterns throughout the two English vowels could be attributed to the poorer discrimination in the particular consonantal contexts.