Noise –induced hearing loss in school age children: questionnaire , otological and audiometric study

Introduction
Some data indicate that adolescents are put at risk of noise-induced hearing loss (NIHL) from exposure to noise related to their behaviors. This study aimed to assess the prevalence of NIHL considering that even minimal loss may limit ability to work of prospective adult employee.

Methods
The representative sample of 700 pupils of secondary schools, 13-18 years old was subjected to otological and audiometric examination. Hearing thresholds were measured by means of Interacustics AA 222 audiometer in the range of 250-8000 Hz. The questionnaire was given before examination to determine the frequency and duration of visits to discotheques or pop/rock concerts and use of personal audio players (PAPs).

Results
Fifty seven pupils (8.1%) were excluded from further evaluation because of recognized the middle ear pathologies or another confounding agents.The resultant sample consisted of 643 children and the analysis of questionnaires have allowed to separate three groups:131 pupils (20.4 %) not exposed ,169 (26.3 %) with mild exposure ( discos/concerts 1x monthly; PAPs 1-3 hours daily, 1-3 x weekly) and 343 (53.3 %) with large exposure(disos/concerts 1-2 x weekly or more; PAPs 4-7 hours daily or more, 4-7 x weekly). In both exposed groups the notched hearing losses at 4000 or 6000 Hz were detected respectively in 18 pupils (10.7 %) with mild exposure and in 56 (16.3%) with large one. The mean hearing thresholds of the not exposed teenagers vs. those in exposed groups differed significantly ( p < 0.005) .

Discussion
The above findings are similar to results obtained in the US Third National Health Survey (Holmes et al,2004) and also in high school teenagers investigation in Mexico City (Martinez-Wbaldo et al, 2009).
Our study proves that a loud music may create a risk for hearing damage in school age children and promotion/education of healthy listening habits should be urgently introduced.