Hierarchy Of Noise Risk Control: The Definitive Guide

Excessive noise levels can lead to various adverse effects on human health, including hearing loss, tinnitus, and other physical and psychological issues. Therefore, it is crucial to manage noise levels in different environments effectively. To achieve this, organizations and individuals must understand the hierarchy of noise risk control measures and implement them accordingly.

In this article, we present a comprehensive guide to the hierarchy of noise risk control, including the different levels of control measures and their applications. We also discuss the importance of effective noise risk management and noise control techniques. Whether you are a health and safety professional, an employer, or an individual concerned about noise exposure, this guide provides essential information and practical strategies for managing noise risks effectively.

The WHS Regulations require duty holders to work through a hierarchy of control to choose the control measure that most effectively eliminates or minimizes the risk in the circumstances. The hierarchy ranks the ways of controlling the risk of hearing loss from noise from the highest level of protection and reliability to the lowest so that the most effective controls are considered first.

Occupational health is concerned with physical and psychological and chemical and biological hazards. The physical and occupational hazards have been well-known for many years, and recent emphasis has been on developing lower-risk workplace environments. Physical hazards include electricity, display screen equipment (DSE), manual handling covered in earlier chapters, and noise, vibration, and radiation, which are discussed in this chapter.

However, it is only really in the last 20 years that psychological hazards have been included among the occupational health hazards faced by many workers. This is now the most rapidly expanding area of occupational health and includes topics such as mental health and workplace stress. In this blog post, we’ll learn the techniques and the hierarchy of control measures to control noise.

What Is Occupational Noise Exposure?

Noise, or unwanted sound, is one of the most pervasive occupational health problems. It is a by-product of many industrial processes. Sound consists of pressure changes in a medium (usually air) caused by vibration or turbulence. These pressure changes produce waves emanating away from the turbulent or vibrating source. Exposure to high levels of noise causes hearing loss and may also cause other harmful health effects. The extent of damage depends primarily on the noise’s intensity and the exposure duration.

Noise-induced hearing loss can be temporary or permanent. Temporary hearing loss results from short-term noise exposure, with normal hearing returning after rest. Generally, prolonged exposure to high noise levels gradually causes permanent damage over time.

OSHA’s hearing conservation program protects workers with significant occupational noise exposures from hearing impairment, even if they are subject to such noise exposures over their entire working lifetimes. This publication summarizes the required component of OSHA’s hearing conservation program for the general industry. It covers monitoring, audiometric testing, hearing protectors, training, and recordkeeping requirements.

Hierarchy Of Control For Noise Hazard

Importance Of Effective Noise Risk Management

Effective noise risk management is crucial for maintaining a safe and healthy workplace environment. Exposure to high levels of noise can cause hearing loss, tinnitus, and other serious health problems. It can also contribute to stress, fatigue, and decreased productivity.

Organizations can help protect their employees’ health and well-being by implementing effective noise risk management strategies while reducing the risk of noise-related accidents and incidents. Some key benefits of effective noise risk management include the following:

  • Preventing hearing loss: Organizations can help prevent hearing loss in their employees by identifying and mitigating sources of excessive noise.
  • Improving productivity: Excessive noise can be a major distraction, making it difficult for employees to focus on their work. By reducing noise levels, organizations can improve productivity and efficiency.
  • Enhancing safety: Excessive noise can mask important auditory signals, such as warning alarms or verbal communication. Organizations can enhance workplace safety and reduce the risk of accidents and incidents by reducing noise levels.
  • Compliance with regulations: Many countries have regulations governing workplace noise levels. Organizations can ensure compliance with these regulations and avoid fines or penalties by implementing effective noise risk management strategies.

Effective noise risk management is essential for creating a safe, healthy, and productive work environment. By identifying and mitigating sources of excessive noise, organizations can help protect their employees’ health while reducing the risk of accidents and incidents. In addition, they can ensure compliance with relevant regulations and avoid costly fines or other penalties. Therefore, implementing effective noise risk management strategies is important to any organization’s health and safety program.

Noise Control Techniques

In addition to reduced time exposure of employees to the noise source, there is a simple hierarchy of control techniques:

  • Reduction of noise at source;
  • Reduction of noise levels received by the employee (known as attenuation); 
  • Personal protective equipment should only be used when the above two remedies are insufficient.

Reduction Of Noise At The Source

There are several means by which noise could be reduced at the source:

  • Change the process or equipment (e.g., replace solid tires with rubber tires or replace diesel engines with electric motors); 
  • Change the speed of the machine; 
  • Improve the maintenance regime by regularly lubricating bearings and tightening belt drives.

Attenuation Of Noise Levels

Many methods of attenuating or reducing noise levels are covered in detail in the guide to the Regulations.

The more common ones will be summarised here.

  • Orientation or re-location of the equipment – turn the noisy equipment away from the workforce or locate it in separate and isolated areas.
  • Enclosure – surrounding the equipment with good sound-insulating material can reduce sound levels by up to 30 dB(A). Care will need to ensure that the machine does not become overheated.
  • Screens or absorption walls – can be used effectively in areas where the sound is reflected from walls. The noisy equipment rooms are lined with sound-absorbent material, such as foam or mineral wool, or sound-absorbent (acoustic) screens placed around the equipment.
  • Damping – the use of insulating floor mountings to remove or reduce the transmission of noise and vibrations through the structure of the building, such as girders, wall panels, and flooring.
  • Lagging – the insulation of pipes and other fluid containers to reduce sound transmission (and, incidentally, heat loss).
  • Silencers – usually fitted to engines that exhaust gases to the atmosphere. Silencers consist of absorbent material or baffles.
  • Isolation of the workers – providing soundproofed workrooms or enclosures isolated from noisy equipment (a power station control room is an example of worker isolation).
  • Immediate noise reduction benefits are often achieved for noise control equipment (e.g., noise enclosures) in good repair.

Hierarchy Of Noise Risk Control

The Hierarchy of Control is a system used to rank the effectiveness of different safety controls. The hierarchy starts with the most effective control at the top and moves down to the least effective control at the bottom. The most effective control is elimination, followed by substitution, engineering controls, administrative controls, and personal protective equipment. So now, we’ll discuss each step of the noise control measures using a hierarchy of control.

1. Eliminate The Risk

If it’s impossible to eliminate the noise completely, the next best step is to try to control it at the source. This can be done by introducing engineering controls. These are changes to how a task is carried out or the equipment used to reduce the noise hazard. For example, using a quieter machine model or enclosing the noisy machinery in a sound-proofed booth.

2. Minimize The Risk To People

If it’s impossible to control the noise at the source, you’ll need to take steps to minimize the risk to people. This includes using distance, barriers, and sound-absorbing surfaces to isolate the noise source from people. It might also include providing personal protective equipment, such as earplugs or earmuffs, to employees exposed to noise.

Noise Hierarchy Of Control

Monitor The Risk

Even if you’ve taken steps to control the noise, you must monitor the risk to ensure it remains acceptable. This includes measuring the noise levels and conducting regular hearing tests for employees exposed to noise. It’s also important to have a system in place so that employees can report any concerns about noise exposure.

These are some further controls measured to reduce the noise in the workplace.

  • Substitute the hazard with plants or processes that are quieter. For example, instead of using a hammer to break up concrete for demolition, you can use a jackhammer (which produces less noise) or explosives (which produce no noise).
  • Modify plants and processes to reduce noise using engineering controls. For example, if your company manufactures products from metal sheets, you could purchase machines that cut out holes for windows or doors on those sheets before rolling them into coils for shipping, so you don’t have to use loud saws or drills during production.
  • Isolate the noise source from people by using distance, barriers, enclosures, and sound-absorbing surfaces. For example, if you have an employee who spends all day working on a machine that produces a lot of noise (like a drill press), they might want to wear earplugs.

If there is a remaining risk, it must be minimized so far as is reasonably practicable by implementing administrative controls. If risk remains, suitable personal protective equipment must be provided and used. When used independently, these two control measures tend to be the least effective in minimizing risks because they rely on human behavior and supervision.

3. Substituting Plants Or Processes To Reduce Noise

Buy ‘Quiet’

One of the most cost-effective and long-term ways of reducing noise at work is to introduce a purchasing and hiring policy to choose the quietest plant for the job. This can be done by obtaining information on noise emission (for example, data on sound power level or sound pressure level at the operator position) from the plant’s manufacturer, importer, or supplier and comparing it to determine the quietest plant.

Ask the suppliers about the likely noise emission where you will operate the machinery and under standard test conditions. You can compare the information if you ask all suppliers the same question. Sound power level data will only ever be a guide as many factors affect the actual noise levels experienced by your workers, but it will help you buy quieter machines. You should purchase or hire only from suppliers who can demonstrate a low-noise design, with noise control as a standard machine part, not as an optional extra.

Change The Way You Do The Job

It’s not just the volume of the sound that is a problem, but also the duration. Noise can be very disruptive and distracting for those near it. A different way of doing the job may provide the same result with much less noise. For example, bending metal in a vice or a press is quieter than hammering it into shape, welding is generally quieter than riveting, gluing is quieter than hammering in nails, clipping is quieter than stapling, and lowering materials in a controlled manner is quieter than dropping them on hard surfaces.

4. Using Engineering Controls

Engineering controls are devices or systems that provide a physical barrier between the worker and the hazard. Engineering controls can be used for ventilation systems, enclosures, or process changes that isolate workers from hazards. When selecting engineering controls, it is important to consider the control’s feasibility, effectiveness, and durability. Engineering controls are often the most effective way to reduce exposure to hazards in the workplace.

When considering minimizing noise at its source, a good understanding of the plant operation or process is necessary.

Examples of engineering control measures include:

Eliminating impacts between hard objects or surfaces by

  • Minimizing the drop height of objects or the angle at which they fall onto hard surfaces
  • Using absorbent lining on surfaces to cushion the fall or impact of objects
  • Fitting exhaust mufflers on internal combustion engines
  • Fitting silencers to compressed air exhausts and blowing nozzles
  • Isolating a vibrating noise source to separate it from the surface on which it is mounted
  • Using rubber mounts and flexible connections
  • Ensuring gears mesh together better
  • Fixing damping materials (such as rubber) or stiffening panels to reduce vibration
  • Fitting sound-absorbing materials to hard reflective surfaces
  • Turning down volume controls
  • Changing fan speeds or the speeds of particular components
  • Changing the material the equipment or its parts are made of (change metal components to plastic components).

Isolating the source of noise

Examples of isolating the source of noise from workers include:

  • Building enclosures or soundproof covers around noise sources
  • Using barriers or screens to block the direct path of sound
  • Locating noise sources further away from workers
  • Using remote controls to operate noisy plants from a distance.

5. Using Administrative Controls

Administrative controls in noise exposure are used to reduce the amount of noise a person is exposed by reducing the time they are exposed. These controls can reduce noise exposure in both occupational and non-occupational settings. Administrative controls are often the most feasible and effective way to reduce noise exposure.

A variety of administrative controls can be used to reduce noise exposure. Some are as follows:

  • Organizing schedules so that noisy work is done when only a few workers are present
  • Notifying workers and others in advance of noisy work so they can limit their exposure to it
  • Keeping workers out of noisy areas if their work does not require them to be there
  • Sign-posting noisy areas and restricting access
  • Providing quiet areas for rest breaks for workers exposed to noisy work
  • Limiting workers’ time in noisy areas by moving them to quiet work before their daily noise exposure levels exceed the exposure standard.

If you rely on administrative controls, you should conduct regular checks to ensure they are complied with.

Hierarchy Of Noise Control

6. Using Personal Hearing Protectors

Personal hearing protectors, such as ear-muffs or ear-plugs, should be used in the following circumstances:

  • When the risks arising from exposure to noise cannot be eliminated or minimized by other more effective control measures,
  • As an interim measure until other control measures are implemented
  • Extra protection is needed above what has been achieved using other noise control measures.

If the use of personal hearing protectors is necessary, the hearing protectors must be worn throughout the period of noise exposure. Removing personal hearing protectors for short periods significantly reduces the effective attenuation (noise reduction) and might provide inadequate protection. For example, a worker wearing a hearing protector for a full 8-hour day will receive the 30 dB maximum protection level. However, one hour without wearing the hearing protector causes the maximum protection level to fall to 9 dB.

Areas, where people may be exposed to hazardous noise, should be signposted as hearing protector areas, and the boundaries of these areas should be clearly defined. Workers and other persons, including managers and visitors, should not enter these areas without wearing appropriate personal hearing protectors, regardless of how long they stay in the hearing protector area.

Where sign-posting is not practicable, you should make other arrangements to ensure that workers and others know when personal hearing protectors are required. For example:

  • Attach prominent warning notices to tools and equipment indicating that personal hearing protectors should be worn when operating them
  • Provide written and verbal instructions on how to recognize circumstances in which personal hearing protectors are needed
  • Ensure effective supervision of identified hazardous tasks


Noise control is an important component of any workplace safety program. There are a variety of methods available to reduce noise exposure, including engineering controls, administrative controls, and the use of personal hearing protectors. By following these methods and taking the necessary steps to control noise in your workplace, you can ensure that all workers are protected from hazardous noise levels.

Remember: the best way to protect workers from hazardous noise is to eliminate or reduce it at its source. Suppose you cannot eliminate or reduce the noise. In that case, additional measures such as engineering controls, administrative controls, and personal hearing protectors should be used to protect workers from excessive noise exposure. Remembering that the employer must ensure that all workers are adequately protected from hazardous noise levels.

By implementing these noise control measures, you can help protect your workers from hearing damage and other health effects caused by exposure to excessive noise. Moreover, a safe workplace helps create a productive working environment for employers and employees. So don’t wait; take the necessary steps to protect your workforce today!