studying persian vowel formants in esfahani cleft-lip-and-palate students aging 7-9 years

introduction: on the importance of the formant frequency, it is enough to say that the first three formants of a vowel and their internal relationships are the major components in detection of vowel type by listener. moreover, the quality of a vowel depends on its factorial frequencies. the main application of measuring factorial frequency is for description of vowel errors because recognizing abnormal vowels, based on the listener's perception, is not as exact and accurate as measuring their frequency by instrumental assessments. this study aimed at investigating first three formants of vowels in farsi language among 7-to-9-year-old children with cleft lip and palate in isfahan   methods: it was a descriptive cross-sectional study. participants were twenty-three children with cleft lip and palate with an age ranging from 7 to 9 years. the raw data was gathered directly by the interviewer, and then the subjects underwent the persian vowel test. first formant (f 1 ), second formant (f 2 ), and third formant (f 3 ) of all six vowels of farsi language was obtained via real analysis and dr. speech software and the apparatus speech studio. the scores relevant to each sample was recorded in separate data sheet designed for this study. statistical analysis was performed on all data of interest.   results: the highest average amounts for of f 1 , f 2 , and f 3 were respectively in / æ/ (685 hz), /i/ (1542 hz), and /i/ (3264 hz). the lowest average amount of these formants was for /i/ (422 hz), /u/ (953 hz), and / æ/ (2565 hz), respectively.   discussion and conclusion: the results of present study showed that f 1 increased in vowels /i/ and /e/ implicating decreased height of tongue. it is also observed that f 2 decreased in vowels /i/ and /e/ showing a backward movement of tongue during production of these vowels. key word : farsi language vowels, vowel space, cleft lip and palate, formant structure, dr. speech instrument