ABSTRACT
Despite the progress in noise control engineering, there are many noisy environments where noise reduction measures are neither technically nor environmentally feasible. In these environments, personal hearing protection is often the only measure available to significantly reduce daily noise exposure. This chapter discusses the various types of hearing protection devices or defenders (HPD), the acoustical performance, methods of estimating resultant levels, and selection guidelines. Earplugs can be broken down into reusable types and disposable types. The acoustical performance of hearing protection devices is determined by measurements in accordance with industry standards. In summary, estimating the actual attenuation of hearing protection devices from laboratory test data has inherent risks. Variables associated with fit, vibration, bone conduction, actual spectral noise levels, and so forth, limit the estimate accuracy to, at best, the first order. Therefore, a margin of safety should always be included in any selection.
