comparing the formant frequencies of three persian long vowels produced by cochlear-implanted and normal-hearing children

introduction: the feedback provided by auditory apparatus equips normal hearing people with an important controlling mechanism over the speech production processes. the speech of hearing-impaired children is both perceptually and acoustically abnormal. this study tried to compare the formant frequencies of three long vowels in persian-speaking children who used cochlear implant and those who were of normal-hearing ability. materials and methods: 20 cochlear-implanted (ci) children and 20 normal-hearing children with the age ranged from 5 to 10 years participated in this study. all participants were native speakers of persian who were asked to produce prolonged vowels /i/, /u/ and /ɒ/. the averaged f1 and f2 were calculated for each examinee using praat software (version 5.3.13). independent t test was conducted to examine the possible differences thatf1 and f2 values and f2 to f1 ratios may have in the two groups. results: study results revealed a relative increase in the f1 mean values of all the three vowels produced by ci children. this difference was, however, significant only in the first formant of vowel /i/ (p = 0.011).the mean values of f2/f1 ratio for vowel /i/ showed a statistically significant difference between the two groups (p = 0.01). conclusion: f1 formants are increased in cochlear-implant children. this condition might be due to a process in which the lack of auditory feedback is compensated by the proprioceptive feedback that is provided through the exaggerated articulation. the changes in f1 and f2 imply a reduced vowel space, in other words, vowel space is slightly centralized in ci children.