Real-time three-dimensional ultrasound imaging of pre- and post-vocalic liquid consonants in American English

Speech sound articulation is typically characterized in the mid-sagittal plane. However, lateral segments, such as the /l/ category in most varieties of English, are usually identified in introductory phonetics courses as exceptions to this rule. On the other hand, many productions of post-vocalic /l/ in varieties spoken in the lower Mid-west U.S. are noted as being non-lateral, involving only a dorsal articulation very different from the canonical coronal occlusion. Furthermore, a large body of literature indicates multi-constriction articulations, which vary by syllable position, for liquids like American English /l/ and /r/. This research presents results from a study of constriction location and laterality in pre- and post-vocalic /l/ and /r/ using real-time 3D ultrasound images of tongue motion, digitized impressions of the palate, and time-aligned acoustic signals.