Analysis, modelling and synthesis of formants of British, American and Australian accents

The formant space of three major English accents namely British, American and Australian are modelled and used for accent conversion. Accent synthesis, through modification of the acoustic parameters of speech, provides a means for assessing the perceptual contribution of each parameter on conveying an accent. An improved method based on a linear prediction (LP) model feature analysis and a 2-D hidden Markov model (HMM) is employed for estimation of formant trajectories of vowels and diphthongs. Comparative analysis of the formant space of the three accents indicates that these accents are partly conveyed by the fronting and backing of vowels. It is found that the first formants of the vowels of British and American English accents are higher than those in Australian accent while Australians have higher second formants in vowels compared to Americans and British. The estimates of the distributions of formants for each accent are used in a speech synthesis system for accent conversion. Perceptual evaluations of accent conversion results illustrate that formants, in particular the second formant, play an important role in conveying accents.