The Persian vowel formants in normal, moderate and severe hearing impaired students age 7-9 years in Isfahan

Nowadays, auditory perception is not a complete method to assess vowels quality and we need to use more objective instruments. In this study we want to determine and compare the persian vowels formants in normal and hearing Impaired students in 7ـ9 year old children of Isfahan. This cross sectional study was performed on 64 normal and hearing impaired students. Background information was by interview and then, vowel production test was performed. First three formants of each vowel were obtained and recorded by speech studio soft ware and Dr. Speech device Data were compared between groups. Mean F1 and F2, and F2/F1 and F3/F1 ratio of Persian vowels between these three studied groups were different significantly. Mean F3 of /o/, /e/ and /a/ in all groups was different significantly. Although we could not find such a significant differences for /u/, /i/ and /æ/ between these groups (p<0. 05). The most important difference between normal and hearing impaired children is their vowel Space, and we found that, the more sever the hearing impairment is, the closer vowel space will be seen. The hearing impaired children rely mostly on their proprioceptive sense because of their hearing deficiency and it causes less movement of the tongue, so they usually substitute vowels which have similar F1 and F2.