This is a cross-sectional study.
Acoustic analysis of isolated vowels was performed in 33 individuals with IGHD, age 44.5 (17.6) years (16 women), and 29 controls, age 51.1 (17.6) years (15 women).
Compared with controls, IGHD men showed higher values of F3 [i, e, and ε], P = 0.006, P = 0.022, and P = 0.006, respectively and F4 [i], P = 0.001 and lower values of F2 [u], P = 0.034; IGHD women presented higher values of F1 [i and e] P = 0.029 and P = 0.036; F2 [ɔ] P = 0.006; F4 [ɔ] P = 0.031 and lower values of F2 [i] P = 0.004. IGHD abolished most of the gender differences in formant frequencies present in controls.
Congenital, severe IGHD results in higher values of most formant frequencies, suggesting smaller oral and pharyngeal cavities. In addition, it causes a reduction in the effect of gender on the structure of the formants, maintaining a prepubertal acoustic prediction.