Vowel characteristics associated with alaryngeal speech of Cantonese : a study of vowel formant characteristics

Abstract

The present study examined the differences in vowel articulation between alaryngeal and laryngeal speech of Cantonese. First (F1) and second (F2) formant frequencies associated with seven Cantonese vowels /i, y, ɛ, a, ɔ, oe, u/ produced by forty alaryngeal (twelve esophageal (SE), ten tracheoesophageal (TE), ten electrolaryngeal (EL), eight with pneumatic artificial larynx (PA)) and ten laryngeal (NL) speakers were obtained. Six derived formant metrics, including the First and Second Formant Range Ratios (F1RR & F2RR), Triangular and Pentagonal Vowel Space Areas (tVSA & pVSA), Formant Centralization Ratio (FCR) and Average Vowel Spacing (AVS), were subsequently calculated to investigate the articulatory differences between alaryngeal and laryngeal speech. Results showed a general reduction in articulatory range and tendency of centralization in Cantonese alaryngeal speech, with significant difference in PA and EL but not SE and TE speech when compared with NL speech. The discrepant results between alaryngeal speakers using an external and internal sound source indicated fundamental differences in their respective resonance and articulatory patterns. Sensitivity and correlation analyses concluded that a matrix of metrics provided a more comprehensive profile of the articulatory pattern in alaryngeal population.