The Effects of Maxillofacial Surgery on Speech and Velopharyngeal Function

Acoustic analysis of vowel sounds before and after orthognathic surgery

“…Additionally, studies of the functional changes in pronunciation following orthognathic surgery have focused on changes in consonant pronunciation instead of on vowel sounds (Dalston and Vig, 1984;Lee et al, 2002;O'Gara and Wilson, 2007). The formant method, which is used in the field of phonetics, has the advantage of analysing the structural changes in the vocal tract (Bowers et al, 1985).…”

“…Dalston and colleagues studied the pronunciations recorded by 40 females who had previously undergone orthognathic surgery and asked three linguists and language pathologists to classify each according to hypernasality, hyponasality, and pronunciation proficiency. Thus, this research was very subjective, and it relied on auditory qualification (Dalston and Vig, 1984;Lee et al, 2002;O'Gara and Wilson, 2007). Subsequently, Bowers and colleagues studied the changes before and after orthognathic surgery using cephalometric lateral radiography and formant analysis.…”

Role of Speech in Orthognathic Surgery: A Review

“…However, in patients with Class II malocclusion, the lower lip comes in contact with the upper anterior teeth. There is also distortion of sounds like /s/, /z/, /f /, and /3 /.This is due to the presence of deep bite [2].…”

“…These sounds should be produced with tongue-tip approximating the alveolar ridge. Instead, individuals who have Class III malocclusion often produce this sound with the tip of the tongue contacting the maxillary incisors [2].…”

“…When individuals have difficulty closing the velopharyngeal port, airflow and sound energy are directed into the nasal cavity rather than the oral cavity, resulting in speech that is characterized by audible nasal air emission and hypernasal resonance [2]. There could be errors in the sounds like /p/, /b/, /t/, /d/, /k/, and /g/.…”