Measurements of F1 and F2 were made for the four corner vowels produced by typically-developing adolescents and adolescents with Fragile X and Down syndromes. The two high vowels were produced with lower F2 frequencies by the Fragile X and Down syndrome groups than the group of typically developing persons. This is consistent with a hypothesized backing of the tongue.
Index Terms. F1, F2, corner vowels, Fragile X, Down syndrome