Abstract
Introduction The acoustic analysis of speech (measurements of the fundamental frequency and formant
frequencies) of different vowels produced by speakers with the Angle class II, division
1, malocclusion can provide information about the relationship between articulatory
and phonatory mechanisms in this type of maxillomandibular disproportion.
Objectives To investigate acoustic measurements related to the fundamental frequency (F0) and
formant frequencies (F1 and F2) of the oral vowels of Brazilian Portuguese (BP) produced
by male speakers with Angle class II, division 1, malocclusion (study group) and compare
with men with Angle class I malocclusion (control group).
Methods In total, 60 men (20 with class II, 40 with class I) aged between 18 and 40 years
were included in the study. Measurements of F0, F1 and F2 of the seven oral vowels
of BP were estimated from the audio samples containing repetitions of carrier sentences.
The statistical analysis was performed using the Student t-test and the effect size was calculated.
Results Significant differences (p-values) were detected for F0 values in five vowels ([e], [i], [ᴐ], [o] and [u]),
and for F1 in vowels [a] and [ᴐ], with high levels for class II, division 1.
Conclusion Statistical differences were found in the F0 measurements with higher values in five
of the seven vowels analysed in subjects with Angle class II, division 1. The formant
frequencies showed differences only in F1 in two vowels with higher values in the
study group. The data suggest that data on voice and speech production must be included
in the protocol's assessment of patients with malocclusion.
Keywords
speech - voice - speech acoustics - malocclusion
