Hearing loss is a gradual and irreversible process; without regular testing, few workers will realize that they are losing their hearing until it is too late. Therefore, prevention measures must be taken by employers and workers to ensure the protection of workers' hearing.

How do we hear?

Hearing is a series of events in which the ear converts sound waves into electrical signals that are sent to the brain and interpreted as sound. The ear has three main parts: the outer, middle, and inner ear. Sound waves enter through the outer ear and reach the middle ear where they cause the eardrum to vibrate.

The vibrations are transmitted through three tiny bones in the middle ear, called the ossicles. These three bones are named the malleus, incus, and stapes (and are also known as the hammer, anvil, and stirrup). The eardrum and ossicles amplify the vibrations and carry them to the inner ear. The stirrup transmits the amplified vibrations through the oval window and into the fluid that fills the inner ear. The vibrations move through fluid in the snail-shaped hearing part of the inner ear (cochlea) that contains the hair cells. The fluid in the cochlea moves the top portion of the hair cells, called the hair bundle, which initiates the changes that lead to the production of nerve impulses. These nerve impulses are carried to the brain, where they are interpreted as sound. Different sounds move the hair bundles in different ways, thus allowing the brain to distinguish one sound from another, such as vowels from consonants. Continuous exposure to loud noise can damage the structure of the hair cells, resulting in hearing loss and tinnitus (ringing in the ears).

NIHL can be caused by a one-time exposure to loud sound as well as by repeated exposure to sounds at various loudness levels over an extended period of time. The loudness of sound is measured in units called decibels. For example, normal conversation is approximately 60 decibels, the humming of a refrigerator is 40 decibels, and heavy city traffic noise can be 85 decibels. Examples of sources of loud noises that cause NIHL are motorcycles, firecrackers, and firearms, which emit sounds above 120 decibels. Sounds of less than 80 decibels, even after long exposure, are unlikely to cause hearing loss.

People with hearing loss often become socially isolated because they cannot communicate easily with others. They also may not be able to hear warning signals, and so may have an injury.

For more information, please see:

Noise and Hearing Loss in Construction

Noise and Hearing Damage in Construction Apprentices

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Who gets hearing loss from noise?

We cannot assess the risk for noise induced hearing loss from one single task, but it is clear that masons and bricklayers are all at high risk of hearing loss from noise.

From 1999-2004 the University of Washington Department of Environmental and Occupational Health Sciences measured noise exposure among nine trades. Construction workers overall were exposed over 85 dBA in about 70% of work shifts using a NIOSH exposure standard.(The NIOSH standard is more sensitive to intermittent and variable noise, and because of that is a better representation of the actual risk of hearing loss in construction.If we were to use the OSHA method, the percentage of work shifts over 85 dBA falls to 29.5%)

Among masons, the average exposure was 88.5 dBA with the NIOSH method, and 26% of the shifts averaged above 85 dBA as a time weighted average. As shown in the tables below, many tools generate peak noise levels over 110 dBA.

According to NIOSH, approximately 30 million workers are exposed to hazardous noise on the job. While any worker can be at risk for noise-induced hearing loss in the workplace, construction workers often have high exposures to dangerous levels of noise. Most construction workers have significant hearing loss from noise by the time they are 50 years old. Examination programs for construction workers have found that hearing loss (defined as material impairment using the NIOSH formula) was found in:

• 46% of laborers tested in West Virginia and as high as 60% of the retirees
• 50% of 6500 construction workers who had been employed at DOE facilities

Most people's hearing gets worse as they get older.  But for the average person, aging does not cause impaired hearing before the age of 60.  People who are not exposed to noise and are otherwise healthy keep their hearing for many years.  People who are exposed to noise and do not protect their hearing begin to lose their hearing at an early age.  By age 25, for example, the average carpenter has the same hearing as someone who is 50 years old and has worked in a quiet job.

How can you tell if you are exposed to high levels of noise?  If you work in a noisy area and have to raise your voice to talk to someone who is an arm's length away, then the noise is likely to be hazardous.  If your ears are ringing or sounds seem dull or flat after leaving a noisy place, then you probably were exposed to hazardous noise.

Researchers at the University of Washington have measured noise levels in many construction tasks. They found that the average level was 81.4 DBA for all workers in all trades. The tables below give more detail on noise levels and hazards for Masonry tasks and tools: 

Noise exposure in construction
 

Trade TWAs	Mean dBA	% shifts >85 dBA
Iron Worker	91.1	75.6%
Laborer	89.1	61.3%
Carpenter	88.7	59.1%
Masonry Trades	88.5	26.1%
Operating Engineer	88.4	88.7%
Cement Mason	87.7	71.4
Electrician	86.7	65.8%
Sheet Metal Worker	85.7	82.0%
Insulation Worker	81.8	53.5
All Workers Combined	87.8	64.7%

Masonry Tasks, in order of increasing average noise level
 

Tasks	Average Noise Level (dBA)	Maximum Noise Level (dBA)
Break, Rest, Lunch, Cleanup	84.8	103.0
Operating Forklift	88.5	110.9
Manual Material Handling	89.4	105.3
Bricking, Blocking, Tiling	91.6	114.0
Grouting and Mortaring	92.9	113.7
Pointing, Cleaning, Caulking	95.3	115.2
"Other" Tasks	96.4	114.7
Operating Work Vehicle	98.0	116.7

Masonry Tools, in order of increasing average noise level
 

Tools	Average Noise Level (dBA)	Maximum Noise Level (dBA)
Powder Actuated Tool	82.6	111.0
Welding & Cutting Equipment	87.1	108.5
No Tool	89.7	108.5
Hammer, Mallet, Sledge	90.4	115.4
Screw Gun, Drill Motor	91.7	115.8
"Other" Tools	92.8	111.4
Other Hand Power Tools	95.4	118.3
Rotohammer	96.3	120.0
Hand Power Saw	97.2	114.0
Stationary Power Tool	101.8	119.8

The OSHA standards for controlling noise in the construction industry are not as stringent as those in general industry. Although the construction standard says the noise level should not exceed 90 dB, it does not require regular hearing tests for construction workers.

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