Department of ENT, Taleghani Hospital, Shaheed Beheshti University of Medical Sciences and Health Services,TEHRAN-IRAN.
Background: Regarding the noisy environment of schools and teachers’ complaint of hearing loss, the present study was performed for the evaluation of occupational hearing loss in different elementary school teachers. Materials and methods: Between 1995 and 2000, a case- control prospective analytical study was performed in Tehran city on 2000 elementary school teachers (case group) and 2000 individuals that were not teachers (control group).Both groups had similar age and sex. The age range was 25-55 yrs. The case group was selected from 10 educational districts of Tehran (1, 2, 5, 6, 9, 10, 13, 14, 17 and 18). The cases had no history of contact with confirmed hearing loss inducing factors. The control group had the same confounding variables as the case group. Evaluations were carried out in both groups by interview, making questionnaires, physical exam, pure-tone and speech audiometries; the results were recorded. Results: This survey showed that hearing sensitivity of the case group was lower than that of the control group (p <0.001) to different frequencies in both ears in regard to age, occupational history and working in different grades of elementary schools (grades 1 to 5). However, no significant difference was detected regarding hearing loss among the teaching grades and increased occupational history had no influence on this issue. Hearing loss was more significant in high frequencies (4 and 8 kHz) and was more prevalent in the latter (p <0.001). Conclusion: Occupational noise exposure causes high-frequency sensorineural hearing loss. Thus, we recommend to measure intensity of noise in elementary schools and vocational technical schools in particular. In addition, hearing sensitivity level of students and teachers should be measured before the admission and employment, respectively. Annual regular audiometric examinations should also be performed for high-risk individuals and knowledge regarding complications of occupational noise exposure should be increased. As a conclusion, decreasing the number of students in each class, quiet classrooms, decreasing the hours of teaching and using hearing protection devices can prevent noise induced hearing loss. (Tanaffos 2005; 4(14): 61-69)