Vowels: a revisit

Acoustic analysis of five vowels [I, ε, æ, a, ∧] of the Lexical Access database, developped in the Speech Group of the Massachusetts Institute of Technology, was carried out. Vowels were represented throughout their duration by the first three formant frequencies, their amplitudes, the amplitude of the vowel itself, and the fundamental frequency, sampled every 10 msecs, from the onset to the offset of the vowel. Results indicated that an F2 boundary set at about 1500 Hz is capable of separating front and back vowels for both female and male speakers. The use of ‘auditory’ dimensions did not appear to achieve better separation. In the height dimension, the use of F1 produced a large overlap between adjacent vowels due to both inter-speaker and intra- speaker variations. Using auditory parameters such as F1-F0 did not lead to better high/non-high and low/non-low distinction, nor did it produce a male/female normalization effect. Analysis of the relations between formants and amplitudes revealed the presence of a spectral tilt in vowels with high amplitude.