Improvement in vowel articulation of deaf children

Three deaf adolescents who had poorly developed skills in oral communication were given specialized instruction designed to improve their ability to articulate vowels. This instruction was given for 1 hour weekly over a 5-month period, and it led to an improvement in vowel articulation that was substantial enough to be measured acoustically. The instruction emphasized articulatory relations between vowel sounds that are particularly difficult for the deaf to perceive visually or vibrotactually. The formant frequencies of five vowels were measured spectrographically before and after training. The measurements showed that all three children improved in their ability to articulate vowels as indicated by an increased frequency range of the second formant, a reduced amount of overlap in the frequency plots of adjacent vowels, and in more appropriate formant frequency values for individual vowels.