ObjectiveA stable, reliable, and easily implementable clinical diagnostic method for marginal velopharyngeal insufficiency (MVPI) was established on the basis of the subjective hearing judgement of hypernasality and objective examination of velopharyngeal closure to address the lack of unified diagnostic criteria for MVPI.MethodsNasopharyngeal fiberscopy and speech assessment results were collected from postoperative patients with cleft palate. These results were used to analyze the differences in the distribution of nasal resonance in patients with different velopharyngeal closure ratios and the correlation between velopharyngeal closure ratios and nasal resonance status. Mild-to-moderate hypernasality with its corresponding elopharyngeal closure ratio was employed to establish the diagnostic criteria of MVPI. The reproducibility of the criteria and whether the patients with MVPI diagnosed by using the criteria exhibited significantly different speech characteristics compared with other patients were verified.ResultsA strong correlation was found between velopharyngeal closure ratios and nasal resonance (P<0 .001). mild-to-moderate hypernasality mainly corresponded to velopharyngeal closure ratios ranging from 90% to 99%, and the combination of the two characteristics as the diagnostic criteria for mvpi demonstrated good consistency (kappa value="0.789,P<0 .001). moreover, under the diagnostic criteria, significant differences in nasal resonance (P<0 .001), nasal emission (P=0.007), and misarticulation (P<0 .001) were found between patients with velopharyngeal insufficiency and those with mvpi.ConclusionCombining the subjective hearing judgement of mild-to-moderate hypernasality with velopharyngeal closure ratios over 90% under nasopharyngeal fiberscopy provides a reliable and effective clinical method for diagnosing MVPI.