the role of age implantation on formants frequency changing in early and late cochlear implanted children: a study based on perceptual and acoustical assessments

background and aim: age implantation is one of the effective factors on speech production outcomes in cochlear implanted (ci) children. the purpose of this study is to determine the role of age implantation on formant frequencies and production of three persian vowels including /a/, /u/, /i/ in ci children. methods: sixty nine congenitally deaf children who received ci were divided into three groups based on their age implantation. the first and second formant frequencies of vowels, as dependent variables, were measured by sfs software 1.2. the role of children’s age imp­lantation and their gender, as effective factors, were analyzed using a 3 (implantation groups)×2 (gender) two-way anova with a post hoc bonferroni honest significant difference test in spss 16.0. results: the mean values of f 1 /a/, f 2 /a/, f 2 /u/, f 1 /i/, f 2 /i/ were significantly different among different groups (p<0.05). 100% of children who received ci before the age of 2 produced vowels correctly. types of vowel production disorders were mostly nasalization and backing in children who received ci between the ages of 3 to 4 and after age 5. analysis showed that the effect of age implantation on formant frequ­encies of vowels was significant (p<0.05). conclusion: early age implantation (before 2) can cause an improvement of vowel production due to enhancement of f 1 and f 2 placement which is related to height and back-to-front movements of the tongue. also, age impl­antation predicts the quality of vowel pro­duction.