Noise levels experienced by a worker in the performance of an occupation is a relevant consideration for persons with hearing impairments. The definition of noise is scientifically capture by measuring the decibel level (unit of measurement of the loudness of sound). Various documents are available to provide examples of noise levels and the consequences of prolonged exposure to high decibel noise.
The 1972 Handbook for Analyzing Jobs (by the US Dept. of Labor) provides a good starting point for initial study. See pages 333-335 of the HAJ. Note that the chart on page 335 was adapted from work by Peterson and Beranek in 1956.
The 1991 Revised Handbook for Analyzing Jobs (by the US Dept of Labor) did not refer to decibel levels, citing illustrative examples of 5 different categories only. See page 12-10 of the RHAJ - Chapter 12.
Noise sources and their Effects is a chart posted at Purdue University, adapted for a project dealing with exposure to noise in the aircraft industry. [Thanks to Christine DiTrinco for this link).
The National Institute for Occupational Safety and Health (NIOSH) issued a report in June 1998 about Occupation Noise Exposure.
In 2007, Galen Carol Audio published a Decibel Comparison Chart showing various levels of exposure to sound.
In the 2015 ORS Collection Manual, only examples of noise experienced in specfic kinds of familiar environments is detailed. The new ORS will not quantify noise in decibels and will capture only 4 categories: Quiet, Moderate, Loud, and Very Loud.