Estimating Palatal and Pharyngeal Muscle Contraction in Hindi Syllable Pronunciation using Computational Modeling.

Speech, one of the main functions affected by cleft palate, involves a complex orchestra of sound deformation by various organs including the larynx, pharynx, epiglottis, palate, tongue, lip, and other structures complementing them. Although the effects of palatoplasty are traditionally evaluated subjectively, objective parameters have seldom been described to compare the pre- and postrepair functions. The study tries to extract the palatal and pharyngeal muscles while uttering various Hindi syllables and tries to find the percentage contraction of these structures as an objective assessment.  Digital Imaging and Communications in Medicine (DICOM) images while uttering each syllable of the Hindi syllable are obtained by subjecting a healthy volunteer to a dynamic magnetic resonance imaging (MRI). Using freeform geomagic software, 3D models of the structure of the pharynx and palate were created, which were then used to create a finite element model. Different anatomical constraints were applied to the muscles obtained. The finite element model was tested for convergence and a suitably fine mesh was used to obtain the results. The percentage of contraction of the palate and pharynx for uttering different syllables was thus evaluated.  The palate and the posterior pharyngeal walls yielded different contractions for different syllables independent of each other. The highest contraction for the palate and posterior pharyngeal wall was for the syllable /k/ and the lowest regarding the palate was for /h/ and /eː/ for the pharyngeal wall.  Using computational modeling, quantification of speech in terms of percentage contraction of the palate and pharynx has been attempted for the Hindi language. Once validated with a larger population, the database may be used to quantify speech deformities due to structural pathologies in terms of palatal and pharyngeal contractions and help us assess the effectiveness of corrective surgeries for them.