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Effective sound control in the workplace does NOT start with hearing protection  

By Rachel Krubsack

Monitoring may be required
    Today, you must consider if monitoring is needed. When information indicates that any worker's exposure may equal or exceed an 8-hour time-weighted average of 85 decibels (dB), you need to develop and implement a monitoring program. As a general indicator, noise levels could be over 85 dB if workers need to shout to speak to someone three feet away!
    If monitoring is required, an exposure measurement must:
    • Include all continuous, intermittent, and impulsive noise;
    • Be taken during a typical work situation; and
    • Be repeated whenever changes in processes, production, or controls increase noise exposure.
    To begin a noise evaluation, consider the:
    • Noise level in each work area;
    • Equipment and processes that are generating noise (e.g., motors, gears, and belts);
    • Which workers/job functions are exposed to noise; and
    • Length of noise exposure.
    Once you’ve identified the sources and conducted monitoring, see if your sound levels exceed those listed in Table G-16 of 1910.95. If so, your next step — an important one — is to consider ways to reduce the noise or redirect it away from workers.

Engineering controls provide long-term solutions
    “Engineering controls” involve physically changing your work environment to prevent or eliminate worker exposure to a hazard. In the case of noise levels, this may mean modifying or replacing loud machines or equipment. Making physical changes at the noise source or along the sound path is another method. Examples include installation techniques like:
    • Placing a muffler on a machine;
    • Surrounding equipment with an acoustical enclosure;    
    • Erecting barriers/shields close to noisy equipment;
    • Ensuring equipment doors and openings close tightly to contain noise;
    • Installing sound-absorbing material such as foam, vinyl, or fiberglass on walls, floors, or ceilings;
    • Using vibration dampers and isolators to reduce noise on machinery;
    • Using insulators where vibrating machinery is connected to walls and ceilings;
    • Installing speed-breaking plates to decrease the falling distance of falling objects; and
    • Buying quieter machines/tools to replace louder ones.
    Another engineering approach may be to simply move or remove something:
    • Moving or suspending machinery away from as many hard surfaces as possible like walls, floors, and ceilings;
    • Moving equipment so the distance is increased between the worker and the sound source;
    • Separating noisy machines from each other;
    • Relocating workers to a quieter area;
    • Using a remote-control panel to operate a machine from a quieter area;
    • Moving instrument and control panels off vibrating machinery; and
    • Eliminating obstructions such as flanges/valves in ducts and pipes if possible.
    Interestingly, the OSHA Technical Manual says that doubling the distance between the worker and the sound source can decrease the sound pressure level by six decibels!
    Applying practical engineering controls to a noise problem can be challenging. There may not be ready-made solutions. To find the answer, you may wish to take it in steps:
    1. Understand what’s causing the noise,
    2. Determine how the noise is reaching the worker, and
    3. Identify the most appropriate point(s) at which to control the noise, either at the source, along the sound path, or at the worker.

Administrative controls as another option
    If engineering controls aren’t feasible or don’t eliminate or reduce noise to an acceptable level, you may turn to “administrative controls.” Such controls involve managing workers’ activities and safe practices to reduce their noise exposure. Consider:
    • Using job rotation from louder areas to quieter ones throughout the shift;
    • Operating a noisy machine only during a shift when fewer workers are exposed;
    • Scheduling multiple noisy tasks at different times from each other;
    • Reducing the number of workers needed for a noisy task;
    • Removing workers not involved in a noisy task;
    • Encouraging workers to increase their distances from noisy processes;
    • Providing quiet areas, such as a break room, where workers can get relief from workplace noise;
    • Not propping open doors to noisy work areas unless required;
    • Operating moving parts such as fan blades at lower speeds; and
    • Ensuring that workers properly and regularly lubricate and maintain the moving parts on machinery.
    Certain administrative controls may have limited use because shifting from one job to another is not always possible due to worker skill levels or worker contracts. Additionally, rotating workers between quiet and noisy jobs may backfire. That’s because it may reduce the risk of substantial hearing loss in a few workers but increase the risk of mild hearing loss in many workers.

Hearing conservation program
    When it’s not possible to reduce the noise to levels in Table G-16, you must provide hearing protection for affected workers and implement an effective hearing conservation program as outlined in 1910.95. This program covers monitoring, noise exposure computation, audiometric testing, hearing protection, training, worker access to information, and recordkeeping.

Key to remember
    Engineering and administrative controls (not hearing protection) are the first line of defense for eliminating or reducing hazardous noise levels in the general industry workplace.