Motion of apical and laminal /s/ in normal and post-glossectomy speakers

There are two ways to produce an /s/ in English: Apical and laminal. They are almost identical perceptually and the reason for choosing one type is not well understood. This study questions whether one type is preferred in certain conditions, such as high vs low palate height or in post-surgical tongue adaptation. This study examines palate height, and motion of critical and non-critical tongue regions in 8 normal speakers and 8 post-glossectomy patients who have had surgical resection of squamous cell carcinomas of the tongue. Speech was recorded with tagged-MRI and processed to track displacement and velocity of 2-D midsagittal tongue tissue points in the tongue tip and body during the utterance of the word "a souk". Results indicate that subject category had a greater effect on /s/ motion than palate height. Both critical and non-critical articulators in subjects with apical /s/ used higher velocity and displacement on average than subjects with laminal /s/. Compared to patients with larger resections, patients with smaller resections had larger velocities and displacements in both tongue areas suggesting less debility. The single patient with flap reconstruction showed the highest velocity and greatest displacement, suggesting a different type of articulatory compensation.