Tilak Purohit(International Institute of Information Technology - Bangalore (IIIT-B), Bangalore, India) and Prasanta Ghosh(Assistant Professor, EE, IISc)
We propose a technique to estimate virtual upper lip (VUL) and virtual lower lip (VLL) trajectories during the production of bilabial stop consonants (/p/, /b/) and nasal (/m/). A VUL (VLL)is a hypothetical trajectory below (above) the measured UL (LL)trajectory which could have been achieved by UL (LL) if and LL were not in contact with each other during bilabial stops and nasal. The maximum deviation of UL from VUL and its location as well as the range of VUL are used as features, denoted by VUL_MD, VUL_MDL, and VUL_R, respectively. Similarly, VLL_MD, VLL_MDL, and VLL_R are also computed. Analyses of these six features is carried out for /p/, /b/, and /m/ at slow, normal and fast rates based on electromagnetic articulograph (EMA) recordings of VCV stimuli spoken by ten subjects. While no significant differences were observed among /p/, /b/, and /m/ in every rate, all six features except VLL_MDwere found to drop significantly from slow to fast rates. These six features were also found to perform better in automatic classification of slow vs fast rates compared to five baseline features computed from UL and LL comprising their ranges, velocities, and distance from each other.