Formants Frequency and Dispersion in Relation to the Length and Projection of the Upper and Lower Jaws

SummaryObjectiveInvestigate the association between formants frequencies and length and sagittal projection of the maxilla and mandible.Study DesignCross-sectional study.MethodA total of 47 consecutive patients were recruited. Craniofacial measures included; maxillary length (ANS-PNS), mandibular length (Co-Gn), relationship between maxilla and mandible in the sagittal plane (ANB), the sagittal projection of the maxilla (SNA), and mandible (SNB). Subjects were asked to phonate vowels /a/, /i/, /o/, and /u/. Measurements were made in real-time and formant frequencies across F1, F2, F3, and F4 were determined.ResultsThere was a significant negative association between the length of the maxilla and F4 for all the vowels, and a significant negative association between the length of the mandible and F4 for vowels /o/ and /u/. The length of maxilla and mandible also negatively associated with F3 for vowels /a/, /i/, /o/, and vowels /i/, /o/, and /u/ respectively. For the first two formants, the negative association was less pronounced.ConclusionThere was a significant negative association between the formant frequencies F3, F4, and the length of the mandible and maxilla for vowels /a/, /i/, /o/, and /u/.