BMC Public Health 2008, 8:151 http://www.biomedcentral.com/1471-2458/8/151 Other study limitations might include residual confound- ing due to differences in socioeconomic status between the two study groups. This could partly explain the pres- ence of much higher hearing loss levels among the sound technicians. There is no effective treatment for permanent hearing loss resulting from excessive exposure to noise levels. How- ever, this condition may generally be prevented through combined measures in programs against hearing loss (also called hearing conservation programs). Even though the efficacy of these measures (individual hearing protec- tors) for noise protection is determined by tests per- formed in laboratories, their effectiveness in preventing hearing loss due to exposure to cumulative noise depends mainly upon how regularly the workers use this protec- tion. Studies have been demonstrating that if workers do not use hearing protectors for 100% of their working hours, the effectiveness of such devices will diminish rap- idly. For example, using hearing protectors for only 90% of the time will diminish their effectiveness to less than one third of their efficacy [35]. 85.4% of the participants in the sound technician group reported not using hearing protectors during their long working hours (Table 2). This seems to be a common phe- nomenon, because the majority of workers in manufac- turing facilities, percussionists and musicians interviewed in other studies also reported not making use of hearing protectors. They were thus exposed to the risk of high fre- quency hearing loss consistent with noise exposure [16,36-39]. A systematic review has compared the effectiveness of intervention programs versus no intervention regarding the use of hearing protectors among workers exposed to noise levels above 85 dB(A). It was concluded that there was very little evidence regarding the efficacy of long-term school programs for increasing the use of hearing protec- tors among school students. Furthermore, the available evidence did not show that provision of customized/ standardized information to motivate the workers to use hearing protectors was more effective than general infor- mation [40,41]. Programs for preventing hearing loss in industrial organi- zations have been widely defended. Occupational safety and health legislation obliges employees to have preven- tive measures in most countries [42]. In Europe and the USA, verification of noise exposure is mandatory, with periodic examinations on workers exposed to certain noise levels. Studies in the USA have indicated that the use of hearing protectors is increasing, but there is still much to be improved in this respect [43]. Many factors have been reported as influencing the use of hearing protectors, such as the perception of risk likelihood and comfort when using the hearing protectors [35,44-46]. Implementation of hearing conservation programs within this population is of fundamental importance not only for the well being of these individuals, but also for the enrichment of Brazilian popular music, given that it is one of the best products of our country. The perception of hearing is related to the hearing threshold and mainte- nance of good perception through hearing protection measures will have the consequence of developing better professionals who can work to provide even greater value for Brazilian musicians. For this to be definitively recognized and introduced within Brazilian culture and internationally, it will con- tinue to be highly important, as a public health measure, to develop new strategies towards increasing the use of hearing protectors. Conclusion (1) Sound technicians presented a higher prevalence of high frequency hearing loss consistent with noise expo- sure than did the general population, although the possi- bility of residual confounding by unmeasured factors such as socioeconomic status cannot be ruled out. (2) There is some urgency with regard to carrying out stud- ies aiming towards implementing a hearing conservation program through reducing sound levels and making sound technicians aware of the importance of using hear- ing protectors and adopting preventive actions. Competing interests The authors declare that they have no competing interests. Authors' contributions Conception and design: RED. Coordination of the study: VMT and EKS. Data acquisition: RED. Data analysis and interpretation: RED and JFM. Drafting the manuscript: RED. Critical revision for important intellectual content: RED. Data interpretation: RED and JFM. Acknowledgements We would like to thank all the sound technicians who were willing to par- ticipate in this study and the Research Support Foundation of the State of São Paulo (FAPESP) for funding the equipment purchased for this study. We also would like to thank Jessie Ann Le Good, Peter Rabinowitz, Esko Matti Toppila and Liz Sidorkewicz for their support during the revision of the manuscript, and Vanessa Pedrosa for her support during the data collec- tion. References 1. Perda auditiva induzida por ruído/perda auditiva neurossen- sorial por exposição continuada a níveis elevados de pressão Page 7 of 8 (page number not for citation purposes)