Velopharyngeal Gap Size During Sustained Vowel Production Correlates With Perceptual Ratings of Hypernasality in Connected Speech

Purpose: The purpose of this study was to investigate the relationship between perceptual ratings of hypernasality made during connected speech and velopharyngeal (VP) gap size measured in millimeters in the sagittal plane during sustained vowel production using magnetic resonance imaging (MRI). Method: A retrospective cross-sectional analysis was completed. A subgroup of 110 participants from another study with an M_age of 10.1 years presenting for management of VP insufficiency was included. Perceptual ratings of hypernasality during connected speech and measurement of gap size during sustained /i/ production on MRI were performed by raters blinded to the participants’ medical and surgical history. Results: There was a moderate-to-strong, positive correlation (r = .61; p < .001) between hypernasality ratings and VP gap size measured on MRI using sustained /i/. The odds of a higher hypernasality rating increased as the gap size increased (odds ratio = 1.34; 95% CI [1.20, 1.49]; p < .001). The predicted probability for hypernasality ratings of none/minimal/mild steadily decreased as the gap size increased indicating that lower ratings of hypernasality were associated with smaller gap sizes. For the rating of “moderate” hypernasality, the predicted probability of the rating steadily increased up to 8 mm and then decreased as the gap size continued to increase. The predicted probability for a hypernasality rating of “severe” consistently increased as the gap size increased. Conclusions: Hypernasality ratings made at the connected speech level were significantly associated with VP gap size as measured during sustained vowel production. These findings suggest sustained vowel production elicited on MRI may adequately characterize VP gap size in the evaluation of VP insufficiency.