Production and perception of vietnamese short vowels

It is well known that vowels can be produced in isolation, acoustically stable in such a way that they are represented as points in the F1‐F2‐F3 space. Vietnamese language presents 13 vowels, however, Vietnamese can only pronounce 9 vowels [i, u, e, o, ω, a, σ, e, γ] in isolated mode. A previous study showed that the 4 remaining vowels [α, δ , ν , e ] have the same acoustic characteristics (F1, F2, F3) as, respectively, the vowels [a, e, σ, γ], but their dynamic characteristics (the rate of CV transitions) are clearly distinct. Measurements show us that vowels durations of [α, ν] are always shorter than the one of corresponding classical vowels [a, γ] and are not acoustically stable. For test perceptions (with 10 Vietnamese people), synthesized syllables [a‐t] and [γ‐t] with changing vowel duration are recognized as [α‐t, ν‐t] when then duration of initial vowel [a, γ] are 60% ‐ 70% shorter. It means that the vowel duration is an important parameter that allows Vietnamese distinguishing the long vowels an...