Objectives: This study conducts a comparative analysis of the temporal facets of velopharyngeal coarticulation in Persian-speaking adults, differentiating between subjects with and without cleft palate, across three distinct vowel contexts.
Methods: The study included 14 adults who had undergone cleft palate repair, with or without cleft lip and presented moderate to severe hypernasality. Another 14 adults without cleft palate were included in the study. The age range of participants was 18 to 50 years. By utilizing the Praat software, version 6.1.50, the study obtained data for the four temporal parameters by analyzing acoustic waveforms and spectrograms within three distinct vowel contexts. The analysis included the calculation of ratios of nasalization duration to neutralize the influence of speech rate variations between the cleft palate and control groups.
Results: The results revealed that adults with cleft palate exhibited significantly extended durations for the four temporal parameters compared to the control group (P<0.001).
Discussion: The findings underscore that adults with cleft palate demonstrate prolonged nasalization durations in their speech, signifying potential temporal disparities in velopharyngeal coarticulation. This divergence is most evident in the context of the /i/ vowel. The temporal aspects of nasalization, denoting the temporal dimensions of the acoustic impedance related to the oral and nasal cavities, can potentially impact the hypernasality perception in adults with cleft palate. This study proposed that an acoustic examination of speech’s temporal aspects can effectively quantify the degree of nasalization in cleft palate individuals and a control group. Furthermore, the results indicate that the development of motor speech control significantly contributes to the mechanisms underpinning anticipatory and carryover velopharyngeal coarticulation.