ABSTRACT
This chapter provides a description of noise and vibration physics, their sources, health effects and methods to measure and classify them. It describes the components of a hearing conservation program together with practical methods to control noise at the source, its path or at the ear. The chapter discusses methods to control the risk associated with exposure to vibration. It focuses on the nature and characteristics of soundwaves, including their amplitude, frequency, period and wavelength. Sound can be generated in several ways. Emission refers to the radiation of sound from a source. Immission describes the influx of sound at a point. A permanent threshold shift occurs where the cochlear hairs are damaged by prolonged exposure to noise. The hairs may shear from the cochlear membrane. Sound pressure levels describe the amplitude of soundwaves at certain frequencies. The ultimate aim of determining noise immission is to ascertain whether workers' noise exposure exceeds the daily noise dose.
