Noise in the Workplace and Hearing Loss

Exposure to excessive noise over and extended period of time will result in hearing loss. There are also situations where hearing loss may occur very rapidly.

Protecting the hearing of employees is extremely important. Although loss of hearing through aging usually follows a normal pattern, when we are exposed to excessive noise, hearing loss can occur prematurely from excessive exposure to noise in the workplace. Hearing loss is a serious hazard that is often painless, progressive, and permanent.

Loss of one’s hearing reduces the quality of life, and being unable to hear warnings and other auditory signals at work can create serious hazards.Additionally, excessive noise levels have also been associated with digestive problems, irritability, loss of concentration, and even high blood pressure. All of these effects can create their own adverse health effects and hazards, both at and away from the workplace.

Noise sources are numerous.Manufacturing equipment, motor vehicles, heavy construction equipment, power tools, hand tools, aircraft noise, weapons, and even lawn maintenance equipment, to name a few, are some examples where occupational noise may be encountered. It is quite common for people to be exposed to unsafe noise levels that can result in hearing loss, and exposure to excessive noise over an extended period of time will result in hearing loss. There are also some situations where hearing loss may occur very rapidly.

What Can Employers Do to Prevent Hearing Loss?
This is a three-step process to prevent hearing loss in the workplace: recognizing that a noise problem may exist, evaluating the extent of the potential problem, and controlling it.

Recognizing the problem may be as simple as spotting the fact that a worker is unable to properly communicate with another worker a few feet away. But the complexity of the work site, varying exposure scenarios of the employees, and many other situations usually make identification of a noise problem more difficult. Either way, the employer must be able to determine how much noise is in the workplace in a quantifiable manner. Measurements can be done using various soundmeasuring devices, including sound level meters, dosimeters, and octave band analyzers. A sound level meter can be used to get an overview of the noise created by each activity an employee performs or give an overall noise level in a particular area. A noise dosimeter continuously measures the sound levels to which an employee is exposed throughout the day, using a microphone that is positioned near the ear. It provides an 8-hour time weighted average (TWA). An octave band analyzer, which is a more sophisticated device, may be used when there are very predominant frequencies of noise, but often it is not necessary to use such a device unless an acoustics professional is trying to develop a strategy to engineer the noise out.

Any of these measurements should be performed by a qualified professional such as a Certified Industrial Hygienist, Certified Safety Professional, or other qualified health and safety professional.

The Occupational Health and Safety Administration and code of accepted practice dictate that, wherever feasible, controls be accomplished through engineering methods and administrative controls before the use of hearing protection devices. Examples of this are engineering controls that include using quieter manufacturing methods, properly maintaining equipment, eliminating a noise source completely, building enclosures, or the use of sound-damping technology. When engineering controls cannot entirely mitigate the noise exposures, the next step is to use administrative controls.

Administrative controls may include automating the process to remove or limit the time the 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.

The last line of defense is the use of hearing protection devices. When noise exposures are greater than 90dBA as an 8-hour TWA and engineering and administrative controls have not reduced the overall exposure adequately, then hearing protective devices are required. Additionally, when exposures exceed 85dBA as an 8-hour TWA, the employer must implement a Comprehensive Hearing Conservation Program in accordance with 29 CFR 1910.95. This includes defining when the program is to be implemented and for which employees, periodic noise monitoring, employee notifications, allowing employees to observe the noise monitoring, audiometric testing, training, and recordkeeping.

Advantages and Disadvantages of Exposure Controls
There are advantages and disadvantages associated with each line of defense. Engineering controls can be expensive over the short term, yet they may be the most economical method of choice over the long term because, once the problem is engineered out, further investments will be minimal.

Administrative controls require very formal procedures, must be comprehensive, and require that management and employees comply with the procedures implemented. For instance, administrative controls can be easily nullified if a production schedule changes and must be run on other shifts or an employee who normally rotates into an area is not available to relieve the other employee in the noisy area. Finally, a Comprehensive Hearing Conservation Program requires continuous investment and time, which over a long term can amount to considerable and recurring expense. All costs associated with the hearing conservation program are to be provided at no cost to the employee, which requires the employer to bear all the costs of this program.

Assuming that not all the noise sources can be engineered out or exposures reduced through administrative controls, hearing protection devices must be considered. The types of equipment to offer the employee must be determined by the employer; OSHA requires that, when a Comprehensive Hearing Conservation Program is implemented, “Employees shall be given the opportunity to select their hearing protectors from a variety of suitable hearing protectors provided by the employer.”

Choosing Hearing Protectors
Hearing protectors are an accepted method of protecting employees’ hearing. Hearing protection devices include ear plugs, ear muffs, semi-aural bands, and electronic devices that electronically block out noise.

Hearing protectors used in the workplace must have a Noise Reduction Rating (NRR) in accordance with testing set forth by the Environmental Protection Agency.The NRR is a rating assigned to each device that indicates how much noise attenuation the person might be expected to achieve under optimal conditions. It is important to stress that use of hearing protection devices is considered a last resort.

Choosing the right hearing protector requires careful consideration of several elements. At sites where low-frequency noise predominates, ear muffs can be very helpful. Semi-aural bands or ear muffs are also useful in situations where someone periodically goes in and out of noisy environments and needs to remove and put on the device many times throughout the day.

Sites can be very dirty, and therefore employees may want a product that is easy to maintain or requires little or no maintenance. Ear plugs are very useful in these types of situations, although wearers must be careful that their dirty hands do not contaminate the devices.

Another very important factor is how the hearing protector interacts with other personal protective equipment, such as hard hats, eye protection, and welding hoods. For instance, eye protection may interfere with the use of ear muffs.

Finally,one of the most important things for a hearing conservation program to be successful is to get employees to buy into the program. This can be done with appropriate training.When the employees understand what the consequences of losing their hearing can be, it is more likely they will comply with the hearing conservation requirements. There are excellent training tools available, including videos that demonstrate how one’s hearing works and the devastating effect of loss of hearing. Not being able to hear your friends and family, the television, the radio, and the sounds of nature are losses that no one should have to experience as a result of not being protected from excessive noise in their work environment.

This article originally appeared in the September 2008 issue of Occupational Health & Safety.

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