Noise Monitoring

Noise is simply described as unwanted sound and it is one of the most common exposures found in the work environment. Most noise issues in the workplace involve repeated exposure to noise that over time produce a gradual reduction in our ability to hear selected sounds. Occasionally, acute trauma can occur from an unexpected high level sound such as an explosion, which produces temporary or permanent hearing loss in exposed individuals. The key to controlling exposures to Noise is identifying the level of exposure (or sound level) and implementing controls to minimize exposure. 

The Occupational Safety and Health Administration (OSHA) established a regulation to control exposures to Noise in General Industry (29CFR 1910.95). The Permissible Exposure Limit (PEL) is based upon the sound level and duration of exposure and for most work environments with a standard 8-hour work shift, the PEL is 90 decibels-A scale (dBA). An Action Level has also been established at 85 dBA for 8-hour exposures, or an equivalent 50% Dose for work shifts that are not 8-hours. Employees exposed above the Action Level should be included in a Hearing Conservation Program that includes baseline and annual audiometric testing along with training on the effects of noise and types of personal protective devices available. Hearing protection should be available for all workers exposed above the Action Level. The use of hearing protection should be mandatory for all employees exposed to Noise above the PEL or for those who have experienced a Threshold Shift during annual audiometric testing.

Measurement of noise can be quite complex; however, for the purpose of the OSHA Noise standard, employee sound exposure measurements can be conducted in one of two ways that determine if employees are exposed above the Action Level or PEL. Many workplaces can be evaluated using a sound level meter that measures the sound in a work area. This may be acceptable if the sound level is fairly stable and if workers remain in a fixed area. If workers are mobile or if there is a wide fluctuation in the sound level, measurements should probably be made with an integrating sound level meter (noise dosimeter) that collects measurements over time and automatically calculates the sound level during the period sampled.

After determining exposure levels for selected areas, departments or employee exposure groups, efforts should be made to implement controls to protect those employees from noise induced hearing loss. As a minimum, controls should be implemented to comply with OSHA. Engineering noise controls may be needed to reduce risks for hearing loss even lower.