Allophonic variations in visual speech synthesis for corrective feedback in CAPT

This paper presents a visual speech synthesizer providing midsagittal and front views of the vocal tract to help language learners to correct their mispronunciations. We adopt a set of allophonic rules to determine the visualization of allophonic variations. We also implement coarticulation by decomposing a viseme (visualization of all articulators) into viseme components (visualization of tongue, lips, jaw, and velum separately). Viseme components are morphed independently while the temporally adjacent articulations are considered Subjective evaluation involving 6 subjects with linguistic background shows that 54% of their responses prefer having allophonic variations incorporated.