Workplace Noise

A hearing conservation program begins with determining a worker's noise exposure. It is the first step in identifying those employees who must be included in the total hearing conservation program. Several criteria suggest the need for noise assessment:

• If any area has a past record of excessive noise

• If employees complain of discomfort or temporary hearing loss

• If employees are unable to converse easily, without shouting, at a distance of 2 feet.

A dosimeter is the most important instrument in noise assessment. It determines the noise level to which employees are exposed by measuring sound over time and analyzing the information to produce a noise dose, expressed in a percentage. A noise dose, D, is defined as:

where D is the noise dose; C, actual duration of exposure in hours; T, noise exposure limit in hours. The allowable exposure time (Table G-16 of the OSHA regulations) is listed in Table 6.5.1. The employee exposure exceeds the OSHA limits if the noise dose, D, exceeds unity, or 100%.

Where the daily exposure is due to more than one noise level, the ratios for each level are added to compute the total noise dose as follows:

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