Any type of hearing loss can create imperfect development of
   educational skills in primary school children.

          In this descriptive study different types of hearing loss in 22152 six years
   old preschool children of Hamadan province were screened by means of
   history taking from their parents, otoscopic examination and audiometric
   test batteries (including P.T.A., S.D.S, S.R.T, and I.A).

          Overall, 307 children(1.38%) with hearing loss were found that 196 cases
   (63.8%) of them had conductive hearing loss (C.H.L.) , 108 cases (35.2%)
   had sensorineural hearing loss (S.N.H.L.) and 3 cases (0.97%) had mixed
   hearing loss. The causes of C.H.L. in decreasing order of frequency were
   otitis media with effusion, tympanic membrane perforation ± otorrhea ,
   widespread tympanosclerosis and ossicular chain fixation and  congenital
   aural atresia. The causes of S.N.H.L. in decreasing order of frequency were
   unknown ethiology, ototoxic drug consumption, and involvement with
   infectious diseases by children or their mothers during pregnancy, head
   injury and neonatal hyperbillirubinemia.

          The results indicated that officials should pay more attention to
   diagnosis , fallow up and treatment of inflammatory middle ear diseases,
   because they are the most frequent cause of hearing loss in preschool
   children.