Control

When hazardous noise is present in the workplace, consider whether noise controls can be used to decrease employee exposures.

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Can we control the noise?

The concept of a Hierarchy of Controls is well established in occupational health and safety. Simply put, it is more effective to eliminate or decrease the severity of the hazard than to change the way people work or require workers to wear protective equipment.

For example, an employer can adopt a Buy Quiet approach, specifying less noisy equipment and processes during the design phase. However, when eliminating the noise is not feasible, there are approaches to lowering the risk of noise-induced hearing loss, either through engineering a solution or applying an administrative policy to limit noise exposure.

Engineering controls involve modifying the equipment, process, or environment in some way so that less sound energy is created or is transmitted to the workers. Often, the most effective approach is to identify and treat the source of the noise based on the results of a noise control survey.

Administrative controls are policies designed to lower the noise exposure by limiting the time workers spend in high noise areas. These policies are often necessary when engineering controls are not feasible or cost effective.

Key Takeaways

Controlling noise:
- Is considered the most effective method to reduce the noise hazard.
- Can be done by specifying quiet equipment during process design, using engineering controls or implementing administrative controls.
- May allow a company to reduce the number of employees in a hearing conservation program.

Benefits of Controlling Noise

Employers who control noise through various methods may benefit in numerous ways:
1. Reducing the risk of noise-induced hearing loss (NIHL) and associated health effects among employees
2. Eliminating or reducing the cost and time spent on implementing a Hearing Conservation Program (HCP) when employee noise exposure is reduced below the Action Level (AL) of 85 dBA as a result of noise control efforts.
3. Decreasing overall reliance on hearing protection devices (HPDs)
4. Enabling more options for suitable hearing protection devices.
5. Helping improve face-to-face and radio communication because there is less background noise to interfere with speech.
6. Easier to comply with state and federal regulations on occupational noise exposure
7. Showing commitment to employees that the employer is serious about reducing noise hazards

Getting Started With Noise Control

Although you may choose to consult with a noise control engineer to assess your situation and design solutions, it is extremely beneficial to involve the employees who work in noisy areas as part of a team working to find ways to lower the noise. A consultant can bring tremendous technical knowledge but the people who spend each day immersed in the noise can provide some of the most practical and straightforward solutions because they know the processes and equipment so well.

Step 1. Measure workplace noise.

It might seem obvious, but the process of controlling hazardous noise in the workplace cannot really begin until the employer has completed a noise hazard assessment and analyzed the results. By monitoring noise in different areas of the facility and by conducting noise surveys on different processes, tasks and tools, the employer will collect the data necessary to identify groups of workers and areas where noise controls are most needed and prioritize where and how to spend noise control dollars to get the greatest benefit. Then, a more detailed noise control survey can be done to identify the noise sources and select the most appropriate noise control solution.

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Step 2. Buy Quiet

Making equipment and processes less noisy during design and fabrication is more effective and economically efficient than implementing noise controls afterward. Buy Quiet is a type of Prevention through Design approach which places a priority on eliminating or controlling the hazard by specifying machinery or tools that create less noise. This is accomplished when a new production processes is being designed or when older equipment or processes are replaced.

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Step 3. Decide which noise sources pose the greatest hazard

Prioritizing the potential noise control projects is an important step toward achieving the most economic outcome. While it may seem logical to focus attention on the highest noise source in your facility, it is possible that you can achieve a more significant decrease in employee noise exposures by first controlling noise in the areas closest to where a large percentage of your employees are working. Some noise controls are fairly inexpensive and, when successful, can gain tremendous support from employees and management.

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Step 4. Consider noise control options
It is often necessary to implement a multi-pronged approach involving both engineering and administrative controls
- Engineering controls may include modifications to the noise source as well as the sound path. A noise control engineer can help you evaluate the effectiveness of different controls for your unique noise situation, including: isolators, enclosures, dampers, absorbers, and barriers.;
- Administrative controls may be less complicated from a technical point of view but can be disruptive if extensive changes to work schedules and work flow are involved. It is not necessarily difficult to establish time limits for employees working in certain areas or doing specific tasks but enforcement of such limits may create additional complexity in your HCP.
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Step 5. Evaluate feasibility
Employers are required to control noise when “feasible” according to AS/NZS standards, but there has been much debate about what that word “feasible” really means. Demonstrating that a particular noise control solution is technically feasible may be fairly straight forward but documenting the economic feasibility can be a challenge.

Some of the questions to consider are:
- Is the decrease in the sound level that can be achieved with a certain noise control significant enough to justify the cost relative to the cost of a hearing conservation program?
- What are the up-front costs of installation and the long term costs of maintaining the control(s)?
- What effect will the controls have on the processes in our facility and the work flow? How will that impact efficiency?
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Step 6. Evaluate effectiveness of controls

Perform noise measurements once controls are in place and periodically afterward to verify and document the results. Establish a schedule to monitor the effectiveness of noise control materials and mechanisms as they age and, potentially, deteriorate over time due to wear and tear. Whenever changes are made to processes and production, review what the effects may be in terms of existing noise controls.

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Requirements

What is Required?

National regulations have established a permissible Noise Exposure limit of 85 dBA over an 8-hour working shift. Employers must limit the 8-hour TWA noise exposure of employees to 85 dBA or below using noise controls and also have the option to use HPD's when other control are impractical or excessively costly. There is also a maximum or peak exposure limit of 140 dB(C).
Using Hearing Protection in Place of Controls

If noise controls fail to reduce sound levels to the required level or below, employers must provide hearing protection devices (HPDs) and ensure they are used. 3M strongly recommends fit testing of hearing protectors as an indicator of the noise reduction obtained by individual employees.

Basics of Noise Control

In the most basic sense, limiting the noise exposure of employees can be accomplished by applying controls to the noise Source, the noise Path or the Receiver.

Source
The noise source is a vibrating object—a machine or tool creating vibration during operation that radiates into the work area as noise.

Path
Noise travels through the air, of course, but also through solid materials such as floors, walls and windows.

Receiver
In hearing conservation, the receiver is the worker.

Examples of Administrative Noise Controls
Administrative controls are policies designed to lower the noise exposure by limiting the time workers spend in high noise areas. These policies are often necessary when engineering controls are not feasible or cost effective.

For example, an employer can adopt a Buy Quiet approach, specifying less noisy equipment and processes during the design phase. However, when eliminating the noise is not feasible, there are approaches to lowering the risk of noise-induced hearing loss, either through engineering a solution or applying an administrative policy to limit noise exposure.

Source

Operate noisy equipment and processes when fewer employees are present—for example at night

Turn off noise sources in between tasks or when employees are present

Path

Restrict access to noisy areas

Receiver

Rotate employees in and out of noise during the day

Set time limits for certain tasks or use of noisy tools
Examples of Engineering Noise Controls

Engineering controls involve modifying the equipment, process, or environment in some way so that less sound energy is created or is transmitted to the workers. Often, the most effective approach is to identify and treat the source of the noise based on the results of a noise control survey.
Source

- Maintain tools and equipment routinely (such as lubricating gears, replacing gaskets, etc)
- Reduce vibration where possible
- Modify the process or method of production such as changing:
- Speed
- Pressure
- Mechanical controls
- Direction of air flow

Path

- Isolate the noise source using springs or pads to prevent noise from traveling through floors or walls
- Enclose the noise source
- Place a barrier between the noise source and the employee
- Isolate the employee from the source in a room or booth
- Install sound absorbing materials to minimize direct sound transmission or reflection

Receiver

- Use video monitors or remote controls to allow employees to operate equipment at a location farther from noise sources
- Retrain employees to use tools or complete tasks in ways that create less noise
- Require employees to wear hearing protection

Types of Engineering Controls

Noise control images used courtesy Associates in Acoustics, Inc.

Isolation
Springs, foam or other damping materials are used to reduce the transmission of sound from noise sources to floors, walls or connected equipment.

For example, springs on each support of a floor-mounted motor to lessen the sound energy that is passed into the floor and the rest of the building.
Damping
Placing materials such as foam, resin or tape on an object or modifying it so that it vibrates less.

For example, coating the outside of a metal bin with resin to reduce the vibration made when parts are dropped into the bin
Reflection
Barriers or partitions are placed in the sound path to deflect sound away from employees

For example, placing a wall or enclosure around a compressor so employees can work nearby with less direct noise exposure
Substitution
Replacing or modifying components of a noisy system to make less noise

For example, switching to a quieter air nozzle or replacing steel wheels on a cart with low-noise rubber wheels
Modification
Changing a process to make it less noisy

For example, decreasing the distance that parts much drop into a bin so less noise is created
Absorption
Sound-absorbing materials placed in an area to reduce the reflection and buildup of sound

For example, acoustical tiles place on a hard surface to lower sound reflection in a room

Beyond the Basics

The benefits of effective noise control (described above) can be expanded by implementing a Buy Quiet policy.

Why Buy Quiet?
Noise-induced hearing loss can be prevented if the TWA exposure of employees is reduced to the allowable TWA exposure level of 85 dBA or below. Buy Quiet can help employers stay below this. Specifying less noisy tools and processes during the design phase may help employers avoid costly noise controls once long-term purchases and commitments have been made.

Benefits of Buy Quiet
- Reducing the risk of hearing loss
- Reducing the long-term costs of audiometric testing, personal protective equipment, and workers compensation. This savings is applicable across a wide variety of machinery and equipment.
- Helping companies comply with AS/NZS 1269 standards and other noise regulation requirements.
- Reducing the impact of noise on the community.

Have You Considered?

- Having a “noise control contest” by engaging your maintenance workers to come up with solutions to noise problems identified by your workforce?
- Controlling the leaks in systems that use compressed air to save on energy costs as well as reducing the noise exposure?
- How much does your hearing conservation program cost annually per worker? How much can you save by reducing the noise exposure below the action level?
- Starting a “buy quiet” policy so that no additional noise sources are introduced into your production areas?
- Setting a goal to do one or more noise control projects per year?
- Measuring the noise after a noise control is implemented to track the success of the project?
- Creating a log of all the noise control projects?
- Updating employee noise exposure records to reflect the new results and when they took effect?
- Making a strategic plan to lower noise exposures over time, tackling the highest priorities first?

Resources to Learn About Noise Control

Worksafe NZ link

Refer to documents:

Control Guide: Management of Noise at Work
ACOP: Management of Noise in the Workplace. Section

CONTINUE YOUR HEARING CONSERVATION JOURNEY: PROTECT

IMPORTANT NOTE: This information is based on selected current national requirements. Other State or local requirements may be different. Always consult User Instructions and follow local laws and regulations. This website contains an overview of general information and should not be relied upon to make specific decisions. Reading this information does not certify proficiency in safety and health. Information is current as of the date of publication, and requirements can change in the future. This information should not be relied upon in isolation, as the content is often accompanied by additional and/or clarifying information. All applicable laws and regulations must be followed.