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.
Controlling noise:
Employers who control noise through various methods may benefit in numerous ways:
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 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.
It might seem obvious, but the process of controlling hazardous noise in the workplace cannot begin until the employer has completed a noise hazard assessment and analysed 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 prioritise where and how to spend noise control dollars to get the greatest benefit. Lastly, a more detailed noise control survey can be done to identify the noise sources and select the most appropriate noise control solution.
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.
Prioritising the potential noise control projects is an important step towards 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.
It is often necessary to implement a multi-pronged approach involving both engineering and administrative controls.
Employers are required to control noise when “feasible” according to OSHA, MSHA and other regulatory bodies, 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 straightforward, but documenting the economic feasibility can be a challenge.
Some of the questions to consider are:
Perform noise measurements once controls are in place and periodically afterwards 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.
ln the US, OSHA has established a Permissible Exposure limit (PEL) of 90 dBA. Employers must limit the 8-hour TWA noise exposure of employees to 90 dBA or below using "feasible administrative or engineering controls." However, since 1983, OSHA enforcement policy has allowed employers to use HPDs as a substitute for implementing noise controls for TWA noise exposures below 100 dBA. To learn more, refer to the OSHA Field Operations Manual Chapter 4 pages 27-28 (PDF, 2.60 MB).
Unlike OSHA, the Mine Safety & Health Administration (MHSA) requires mine operators to implement feasible noise controls without consideration of the noise reduction provided by hearing protectors. This has resulted in much greater emphasis on noise control in mines with less reliance on hearing protection. To learn more, visit MSHA.
If noise controls fail to reduce sound levels to the OSHA PEL or below, employers must provide hearing protection devices (HPDs) and ensure they are used. However, when HPDs are used as a substitute for noise controls, OSHA requires that employer adjust the Noise Reduction Rating (NRR) of the HPOs for compliance purposes*.
For more detail read our Protect page.
*OSHA, NIOSH and the National Hearing Conservation Association (NHCA) have endorsed hearing protector fit testing as a best practice. 3M strongly recommends fit testing of hearing protectors as an indicator of the noise reduction obtained by individual employees.
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
A 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.
Administrative controls are policies designed to lower 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
Path
Receiver
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
Path
Receiver
Noise control images used courtesy of Associates in Acoustics, Inc.
The benefits of effective noise control (described above) can be expanded by implementing a Buy Quiet policy.
Why Buy Quiet? from NIOSH*
Noise-induced hearing loss can be prevented if the TWA exposure of employees is reduced to the NIOSH recommended exposure level (REL) of 85 dBA or below. Buy Quiet can help employers stay below the REL. 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
* https://www.cdc.gov/niosh/topics/buyquiet/
Estimating the cost savings
Look for tools you can use to evaluate the cost effectiveness of a Buy Quiet approach.
Examples of Successful Control Strategies
The Safe-In-Sound awards program recognises employers and other organisations who have achieved success implementing hearing loss prevention programs and applied innovative approaches to controlling employee noise exposure. Learn more online at www.safeinsound.us.
IMPORTANT NOTE: This information is based on selected current national requirements. Other country 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.