Listen Up!

Although loss of hearing through aging usually follows a normal pattern, when we are exposed to excessive noise at work, this loss can occur prematurely. Damage to our hearing over time often happens without us even being aware of it. It’s a serious workplace hazard and usually painless, progressive and permanent.

Why It’s Important

Loss or reduction of one’s hearing can create some serious hazards at work and can negatively affect your quality of life. It can affect your ability to communicate effectively, heed warnings on the job site and can impact productivity. Exposure to excessive noise levels have also been associated with a variety of health issues including digestive problems, irritability, loss of concentration and even high blood pressure.

Our ears are designed well, but they do have their limits. The problem comes when excessive noise causes damage to the nerves in the inner ear. Our ears can often recover from a short exposure to loud noise, but being around too much noise over an extended period of time will eventually cause permanent nerve damage and hearing loss. The louder the noise and longer the exposure, the greater chance permanent damage will occur.

The sources of work-related noise are numerous. Manufacturing equipment, motor vehicles, heavy construction equipment, power tools, hand tools, aircraft noise, weapons, and even lawn maintenance equipment are some examples where occupational noise may be encountered.

How Loud Is Too Loud?

Most employers and workers have a general idea that exposure to loud noise will equate to hearing damage of some type over time. It’s not exactly a scientific approach, but common sense seems to lead to the use of earplugs and earmuffs in certain situations.

For those interested in getting a real handle on the issue, the first step is to determine whether or not noise is a potential problem in their workplace through some simple self-analysis. A walk-through survey helps in making this decision. Indicators of potentially hazardous noise levels include:

  • Overall noise being louder than busy city traffic
  • Workers having to raise their voices to talk to someone as close as 3 feet away
  • At the end of a work shift, people having to increase the volume of their radio, TV or cell phones in order to hear consistently
  • After working for a few years at that workplace, employees find it difficult to communicate in a crowd or party situation where there are other sounds or many voices

Noise is measured in units called “decibels”, abbreviated as “dB”. Noise levels vary and can range from 1 dB (near silence) to 60 dB (quiet conversation) to 140 dB (a jet engine), with a whole variety of machinery and tool levels falling somewhere in between. Scientific studies have shown that people exposed to noise levels of 85 decibels and above over 8 hours or longer, will gradually lose their hearing over time.

Measuring Noise Levels

Measuring noise levels and workers' exposure is the most important part of any workplace noise control program. It helps to identify work locations where there are potential problems, employees who may be affected, and where additional noise measurements need to be made.

The properties of noise which are important to measure within the workplace include:

  • Frequency
  • Sound pressure
  • Sound power
  • Time distribution

The sensitivity of the human ear depends on the frequency or pitch of the sound that it’s exposed to. If a person hears two sounds of the same sound pressure, but at different frequencies, one sound may appear louder than the other. This occurs because people hear high frequency noise much better than low frequency noise. For this reason, decibel levels for the purposes of safety ratings are displayed as dB (A).

This A-weighting serves two important purposes:

  • It gives a single number measure of noise level by integrating sound levels at all frequencies
  • It provides a standardized scale for noise level as experienced or perceived by the human ear

There are a variety of Sound Level Meters (SLM) available on the market that can help to quickly assess these overall noise levels. The issues can be more complicated however, as a variety of factors come into play. Measuring continuous noise versus higher level intermittent or impact noise for instance. Ideally, these types of measurements should be performed by a qualified individual such as a Certified Industrial Hygienist, Certified Safety Professional, or other qualified health and safety expert. Allowable workplace sound levels also vary by province, so it’s normally a good practice to determine what these, and other standards are, through local occupational health and safety organizations.

What You Can Do About It

Once you have determined that you have an issue with noise levels, how do you go about managing the problem? Generally, companies are required by law to provide a hearing assessment and control program if noise levels are consistently above 85 dB. Most accepted codes of practice dictate that, wherever feasible, controls be established through engineering and administrative methods before the use of hearing protection devices. Basically, trying to control the problem at the source as the first lines of defense.

Engineering

Engineering controls include using quieter manufacturing methods, properly maintaining equipment, eliminating noise sources completely, reducing vibration, building enclosures, or the use of sound-damping technology. When engineering controls cannot entirely eliminate the noise exposures, the next step is to use administrative controls.

Administrative

Administrative controls may include the automating of certain processes to remove or limit the time an employee must work in a particular area, changing operating schedules (such as using noisy equipment on shifts when there are fewer employees), and rotating employees out of noisy areas on a regular basis. This area of your program may also include the posting of sound-level warning signs, employee training, education programs, periodic employee testing, record keeping and program evaluation.

Hearing Protection

In addition to the methods listed above, physical hearing protection is often still necessary where high noise levels exist. The complexity of work sites, varying exposure scenarios of employees, and many other factors lead to this being necessary. See the Products section below for a run-down of what’s available.

Products & Equipment

As discussed, the surest method of preventing occupational hearing damage is to reduce noise at the source by engineering and/or administrative methods. However, in certain workplace conditions, there is very little you can do to reduce noise at the source. In these cases, it becomes necessary for workers to wear hearing protectors to reduce the amount of noise reaching their ears. Before selecting your ear protection devices, ensure that they meet CSA standards for your type of exposure and that they are rated appropriately (Noise Reduction Rating – NRR) from the manufacturer. They should also be convenient to use and comfortable to wear so that there won’t be any excuses not to use them. Fit is also critical for proper function, in addition to keeping them on for the entire time that you’re exposed to high levels of noise. Even a few minutes per day of exposure can lead to hearing damage.

Ear Plugs

The disposable type is made of formable foam that is inserted into the ear canal, where it expands to fit the shape of the individual’s ear. Reusable plugs are pre-molded and made of foam, rubber or silicone. They are available in a variety of sizes to ensure best fit. They also normally come with a case to keep them clean when not in use. Earplugs can be more comfortable in hot or damp work conditions, but don’t offer the safe protection as earmuffs. Plugs shouldn’t be used where sound levels are over 105 dB(A).

Ear Muffs

Earmuffs suppress unwanted noise by completely covering the outer ear. They normally offer greater hearing protection than earplugs, are easier to fit and are preferred where exposure to high noise levels is intermittent only. The heavier and deeper the hard-shell dome has, the greater protection it will offer the user. Where noise levels are very high, a combination of ear plugs and earmuffs can be used.

Band Type

These come on a flexible plastic band that is worn under the chin while the protectors are in the ears. The band can be left resting around the neck while the protectors are not in use. They are designed for convenience in work areas with varying noise levels.

Active Noise Canceling & Communication Headsets

This type uses an electronic system to cancel unwanted background noise while at the same time enhancing the quality of audio delivered through the headset. They can be outfitted with AM/FM radio receivers and are designed to allow the wearer to communicate clearly with co-workers. Special microphones suppress environmental noise to aid in two-way communications.

Workplace hearing protection shouldn’t be taken lightly, it takes both employers and employees working together to make any plan work properly. Through a comprehensive program of assessment, control and protection, the risks of hearing damage on the job can easily be minimized.

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