Acoustic-articulatory evaluation of the upper vowel-formant region and its presumed speaker-specific potency

Abstract

We present some evidence indicating that phonetic distinctiveness and speaker individuality, are indeed manifested in vowels’ vocal-tract shapes estimated from the lower and the upper formant-frequencies, respec-tively. The methodology developed to demonstrate this dichotomy, (cid:12)rst implicates Schroeder’s [8] acous-tic-articulatory model which can be coerced to yield, on a per-vowel and a per-speaker basis, area-function approximations to vocal-tract shapes of di(cid:11)ering formant components. Using ten steady-state vowels recorded in /hVd/-context, (cid:12)ve times at random, by four adult-male speakers of Australian English, the variability of result-ing shapes aligned at mid-length was then measured on an intra- and an inter-speaker basis. Gross shapes estimated from the lower formants, were indeed found to cause the largest spread amongst the vowels of individual speakers. By contrast, the more detailed shapes obtained by recruiting certain higher formants of the front and the back vowels, accounted for the largest spread amongst the speakers. Collectively, these results contribute a quasi-articulatory substantiation of a long-standing view on the speaker-speci(cid:12)c potency of the upper formant region of spoken vowels, together with some useful implications for automatic speech and speaker recognition.