• Engineering controls are the best way to control noise, when such controls are effective, practical and affordable.

Workplace safety and health specialists agree that engineering controls are the best way to control noise. That’s true if the engineering control is effective, practical, and affordable. Replacing a noisy machine with a quiet one, modifying it to make it quieter, or changing the sound path so that the noise never reaches the listener are all examples of engineering controls.

• Replacement. An old, noisy electric hand drill can be easily replaced with a newer, quieter one. But replacing a large, noisy chipper/shredder may not be practical. Instead, the employer might enclose the shredder to isolate the noise.
• Enclose the offending equipment. Creative solutions may also be effective ones. Construction workers were using a concrete mixer to de-grease metal parts by tumbling them in sawdust — effective, but noisy. To reduce the noise level to below 85 decibels, the employer built an enclosure around the mixer with two-by-fours and acoustic sound board, sealing the access door with polyurethane foam. The cost was minimal and the design was effective; it lowered noise levels to 78 decibels.
• Increase the distance. Doubling the distance between the worker and the sound source can decrease the sound pressure level by six decibels. For example, a hazardous 96-decibel noise source at five feet is a safe 84 decibels at 20 feet.
• Reduce the impact. Reducing the height that materials collected in bins and boxes will drop can quiet a noisy process. Employers might consider lining containers with damping materials such as plastic or rubber to keep them quiet.

Applying practical engineering controls to a noise problem can be challenging because there may not be ready-to-order solutions. To find a solution, it is important to:

• Understand what’s causing the noise.
• Determine how the noise is reaching the worker.
• Identify the most appropriate point or points at which to control the noise, either at the source, along the sound path, or at the worker.