The noise protection in the agro-forestry field: a study to analyse the PPE earmuff decay in the time

According to the European Directive 2003/10/CE the PPE (Personal Protective Equipments) noise reduction systems become very important to let the operators' work during the day. This is particularly important in situations like agro-forestry yards, where workers are exposed for long period of times to the noise produced by different types of machineries. With a correct hearing protector position over the ear it is possible to work without reaching the lower noise exposure action values. The actual problem is: how long the manufacturer insertion loss values of earmuffs are correct? How to evaluate the decay of these devices, especially after their use in the agro-forest yard for many seasons? Only analysing a certain number of news, used and at the end of the carrier ear protectors is possible to understand how long they can be used without being dangerous for the worker's health (in fact, if the earmuffs are damaged they can amplify rather than reduce the noise). To obtain more precise information about their characteristics, new ear protectors as well as others after different period of use have been analysed. In this way it has been possible to understand if and how the reduction of the noise damage is maintained during the life time of ear protectors. The acoustic characterisation of earmuffs has been carried out in a specialised laboratory. The comparison among the different insertion loss curves allowed the evaluation of the ageing effect on the acoustic performance of the earmuffs. In such way, a better assessment of the hearing risks for the agro-forestry workers is possible.