Exploring velar function in speech: An integrated approach using nasometry and high-speed nasopharyngoscopy

Abstract

It is well established that coupling between the oral and nasal cavities is controlled by velopharyngeal opening and closing movements and that coarticulatory patterns in these movements can affect both the intelligibility and the naturalness of speech. In addition, poor control can cause individuals to develop undesirable compensatory patterns. Most studies of these patterns have relied on indirect methods to assess both extent and timing of movement due to the difficulty of direct observation of the velopharyngeal port. This study focused on the correlation between indirect and direct methods of assessing both timing and magnitude of velopharyngeal opening for coarticulation using complementary data from nasometry and a novel technique – high-speed nasopharyngoscopy. Nasometry measures the ratio of distinct nasal and oral cavity outflow to determine the degree of nasality in speech. High-speed nasopharyngoscopy captures images of the nasopharyngeal region and can resolve velar motion during speech. By aligning these data, we can infer the functional changes of the velopharyngeal port and show the correlation between its status and resulting acoustic effects. Preliminary findings replicate previous work on coarticulatory patterns associated with prosodic structure and low versus high vowels. This work will illuminate how variability in velar function affects phonetic outputs.