Noise is one of the most common occupational hazards in the U.S. workplace. The National Institute for Occupational Safety and Health (NIOSH) estimates that about 30 million U.S. workers are exposed to hazardous noise. Prolonged exposure to high noise levels may cause hearing loss, create physical and psychological stress, reduce productivity, interfere with communication, and contribute to accidents and injuries by making it difficult to hear warning signals.
Occupational noise can be any sound in any work environment. From a scientific standpoint, sound is a wave of positive and negative pressure disturbances that create a wave. Sound can travel through most mediums – wood, water, metal and air.
When air molecules vibrate in the form of a soundwave, the ear perceives the variations in pressure as sound. The inner ear converts the vibrations into mechanical energy, moving microscopic hairs in the inner ear, which convert the sound waves into nerve impulses. If vibrations are too intense, over time the microscopic hairs can be damaged, causing hearing loss.
Noise is measured in units of sound called decibels. The threshold of hearing is measured at zero decibels. A typical conversation from three feet away is 60 decibels. A freight train from 100 feet away – 80 decibels; a typical construction site – 100 decibels; operating heavy equipment – 120 decibels; a jet taking off from 200 feet away – 130 decibels; and the threshold of pain produced from noise – 140 decibels.
Workplace noise can affect the human body by gradually causing hearing loss over long periods of time. Hearing loss can also contribute to progressive loss of communications, socialization and responsiveness to the surrounding environment. In early stages, it affects the ability to understand bits of speech. Eventually, it affects the ability to hears sounds in general.
When workers have extended shifts (longer than eight hours) in a noisy environment, the effects of excessive noise exposure impacts recovery time for the ears. As a result, the “bruising” of the ear’s microscopic hairs during a work shift can, without daily recovery, result in permanent damage.
Tinnitus, or ringing in the ears, can occur after long-term exposure to high sound levels, or sometimes from short-term exposure to very high sound levels, such as gunshots, producing a disturbance in the inner ear. Individuals with tinnitus describe it as a hum, buzz, roar, ring or whistle, which can be short-term or permanent.
For example, a Center for Disease Control study shows that a 25-year-old carpenter that has several years of exposure to typical construction job site noise (hammering, saw cutting and background noise), has the hearing of a 50-year-old who has not been exposed to the same noise. By the time that 25-year-old turns age 55, he will need to have noises amplified six times above normal levels to hear it.
Data collected by OSHA between 1979 and 2006 of noise measurement levels in more than 224,000 workplaces indicate that everyplace where data was collected had noise levels that exceeded safe levels. Manufacturing, mining, agriculture and construction had noise levels 62 percent to 78 percent of the time that exceeded safe levels.
What can be done to prevent hearing loss?
OSHA requires employers to use feasible controls when workers are exposed to noise at or above permissible noise exposures which range from 90 decibels per hour during an eight-hour work day to 115 decibels during a 15-minute interval. 29 CFR 1926.101 requires employers to provide hearing protectors that have been individually fitted (or determined to fit) by a competent person if it is not feasible to reduce noise exposure below permissible levels using engineering or workplace controls.
Equipment manufacturers have made tremendous strides in designing systems that isolate and dampen vibration and noise when equipment is operating by adding sound absorption materials, improving cab suspension, relocating exhaust systems and through engine design modifications.
Hearing protection devices (HPD) also help control noise exposures. OSHA requires that workers exposed to 85 decibels during an eight-hour shift must have hearing protection available for use.
Earplugs can be worn to protect against certain types of noise, and may not effectively block all noise. Earplugs are better suited for warm and/or humid climates, such as outside construction during the summer. Earmuffs are another type of hearing protector and come in a variety of sizes, shapes and materials, usually in a one-size-fits-all design. Earmuffs should be chosen based on the noise frequency that needs to be reduced. Refer to the EPA label on the manufacturer's product.
Hearing bands are a third type of HPD and are similar to earplugs, but with a stiff band that connects the portions that insert into a worker’s ears. Hearing bands may not provide the same noise dampening as properly fitting earplugs, as the portions that fit into the ears are stationary and cannot be twisted into place like earplugs.
Earplugs, earmuffs, or hearing bands alone might not provide sufficient protection from significantly high noise levels. In this case, workers should wear double hearing protection—earmuffs with earplugs.
Neff Rental employees are required to wear hearing protection devices when they are working in and near areas that subject them to unsafe noise levels. For more information about Neff Rental, visit www.NeffRental.com, or call 888-709-NEFF.