Analysis of vowel production in Mandarin/Hindi/American- accented English for accent recognition systems

Abstract

With globalization and emerging voice-activated systems, accent recognition systems have gained more importance. Foreign-accented English shows different acoustical characteristics from native English pronunciation. It varies based on native language of speakers. This work investigated the similarities and differences between spectral and time-domain characteristics of vowel production for English /hvd/ words spoken by native Mandarin, Hindi, and American English speakers. Fundamental frequency, the first four formants, mel-cepstral coefficients, linear predictive coefficients, harmonicity, spectral centroid, spectral spread, tonality, spectral flatness, pitch range coefficients, and zero crossings rate were examined for male and female speakers of English. One-way ANOVA was performed to find the significant correlations. Lindblom’s perceptual distance of the corner vowels was calculated for further analysis. Our preliminary findings indicated that the vowel spaces of the male L2 speakers were smaller than the male L1 speakers’ vowel space. The F1-F2 space of the corner vowel /ɑ/ presented the most variance among L1 and L2 speakers. The vowel space of the female Hindi-accented English was found to be nearly triangular shaped. For the vowels /i/ and /ɪ/, Mandarin- and Hindi-accented English showed similar characteristics. Short-time energy had significant means between L1 and L2 speakers (p < 0.001) for the vowels /i/ as in ‘heed’ and /ɪ/ as in ‘hid’. Higher F1 frequencies were calculated for the vowels /ӕ/ as in ‘had’, /ε/ as in ‘head’ and /ʌ/ as in ‘hud’ spoken by Mandarin-accented speakers. Time-domain based features provided noteworthy differences between the female L1 and L2 speakers of English. The baseline classification system showed that spectral features had higher impacts on recognizing Mandarin- and Hindi-accented English.