Control noise sources before using hearing protection

A noisy workplace may conjure images of hearing protection, but OSHA requires employers to consider engineering and work practice controls before using personal protective equipment. Reducing or eliminating noise can decrease the number of workers in a hearing conservation program. This not only protects workers’ hearing, but can save the company money.

To get started, conduct a noise assessment. Focus on areas where communication is difficult in a normal voice. Identify all noise sources and determine how the sound is transmitted to the room (it’s often amplified by vibration). Noise sources include motors, gears, belts, points of operation, and any other moving parts. Resonant transmitters include the frames, footings, and housings of equipment. First, consider engineering controls to reduce noise levels.

Source and path controls

Source controls reduce the amount of noise generated. Examples include:

• Maintaining motors and all moving parts in top operating condition.
• Reducing operating speeds to the lowest level consistent with production goals.
• Ensuring that equipment is not in contact with other equipment or with walls.
• Isolating noisy equipment using springs or rubber footings.
• Applying vibration-reducing materials and constructing sound-absorbent hoods around points of operation.

Path controls involve isolating, blocking, diverting, absorbing, or otherwise reducing noise intensity before it reaches employees’ ears. Examples include:

• Moving noisy equipment away from employees (noise intensity decreases with distance).
• Using sound-absorbing acoustical tiles and blankets on floors, walls, and ceilings.
• Enclosing equipment within barriers designed to absorb noise or deflect it in harmless directions, such as toward ceilings covered with sound absorbent material.

Even if hearing protection is still necessary, source and path controls that reduce total noise will also reduce the risk of hearing loss.

Work practice controls

If engineering controls still don’t reduce noise to acceptable levels, consider work practice controls. These are changes in schedules or production such as operating noisy machinery on a second or third shift when fewer people are exposed, or rotating employees through quieter jobs to reduce noise exposure time.

Work practice controls are limited because changing jobs or production schedules is often not possible. In addition, rotating employees between jobs may increase the risk of small hearing loss in many workers.