Phonetic analysis during treatment with rapid maxillary expander. (February 2017) - Biondi, E.
Structured Abstract: Objectives: To investigate possible changes and/or device‐related impairments in phonetic habits produced by rapid maxillary expansion (RME). Materials and Methods: Thirty‐five patients scheduled for RME were divided into two groups: Group A (banded two‐arm Hyrax) and Group B (banded four‐arm Hyrax). Speech samples were collected at six time points, before, during and after RME removal. Acoustical analysis was performed using PRAAT and BioVoice analysis tools. Ten volunteers completed a questionnaire on the acceptability of patient's speech. Maxillary dimensions and palatal volume were measured on dental casts before and after expansion using a digital gauge. Results: Voice analysis showed an increase in the peak frequency of fricative consonants (/s/, /ʃ/) after expansion, whereas there was no change of formant frequencies of palatal consonants (/ɲ/, /ʎ/). Vowel /i/ displayed a lowering of the first formant frequency, and an increase in the second and third formant frequencies. After bonding, Group B showed both a greater reduction in the peak frequency of fricatives and a greater increase in the formant frequencies of palatal consonants than Group A. Conclusion: Rapid maxillary expansion causes a slight phonetic change in the acoustical parameters of both consonants and vowels. The two‐arm Hyrax caused less speech impairment than the four‐arm Hyrax during the treatment.