Objectives Millions of workers worldwide are exposed to noise levels that increase their risk of hearing impairment. Little is known about the effectiveness of hearing loss prevention interventions. Therefore we assessed the effectiveness of non-pharmaceutical interventions for preventing occupational noise exposure or occupational hearing loss compared to no intervention or alternative interventions.

Methods We followed the methods prescribed by the Cochrane Collaboration. We searched 8 different electronic databases to 25 January 2012. We included randomised controlled trials, controlled before-after studies and interrupted time-series of non-clinical hearing loss prevention interventions among workers. Two authors independently assessed study eligibility and risk of bias and extracted data. We combined similar studies in a meta-analysis using RevMan5 and assessed statistical heterogeneity with the I² statistic.

Results We included 25 studies. We found no controlled studies on engineering controls for noise exposure but one interrupted time-series on legislation to reduce noise exposure. Eight studies evaluated effects of personal hearing protection devices. Sixteen studies evaluated hearing loss prevention programs (HLPPs). The implementation of stricter legislation was shown to reduce noise levels in workplaces. Case studies showed that substantial reductions in noise levels can be achieved, but there are no controlled studies of the effectiveness of such measures. Better use of hearing protection devices as part of HLPPs reduces the risk of hearing loss, whereas for other program components of HLPPs we did not find such an effect. The overall quality of studies was low to very low.

Conclusions There is still a considerable risk of hearing loss in workers that are considered to be protected by hearing loss prevention programs. The effectiveness of hearing protection devices depends on training and their proper use. Better implementation and reinforcement of hearing loss prevention programs is needed. Better evaluations of technical interventions and long-term effects are needed.