Mark Stephenson, (2005) defines hazardous noise as sound that exceeds the time weighted average of 85 dBA, meaning the average noise exposure measured over a typical eight-hour work day. Other measures and definitions are used for other purposes. For example, “sound exposure level” accounts for variations in sound from moment to moment, while “equivalent sound level” determines the value of a steady sound with the same dBA sound energy as that contained in a time varying sound. [Ron Chepesiuk, 2005].