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Hearing Safety: What’s Making the Most Noise in the Workplace?

Hearing Safety: What’s Making the Most Noise in the Workplace?

With Independence Day (and Canada Day for our neighbors to the north) behind us, the burgers have been grilled, the beverages drank, and the fireworks ignited. But watching (and hearing the fireworks) got us thinking. A firework, exposed to an individual three feet away can reach 140-150 decibels (dB), well above the 85 dB that can cause permanent hearing loss. However, how does that compare to a piece of machinery? A jackhammer? A concrete saw?

We would like to introduce you to some of the common noises in the workplace, the necessary hearing protections, and the steps you can take to protect your workers.

A Brief Introduction to Hearing and Hearing Loss

When sound waves enter the outer ear, the vibrations impact the ear drum and are transmitted to the middle and inner ear. In the middle ear three small bones called the malleus (or hammer), the incus (or anvil), and the stapes (or stirrup) amplify and transmit the vibrations generated by the sound to the inner ear.

The inner ear contains a snail-like structure called the cochlea, which is filled with fluid and lined with cells with very fine hairs. These microscopic hairs (stereocilia) move with the vibrations and convert the sound waves into nerve impulses–the result is the sound we hear. If these hairs are damaged, this is how hearing loss occurs.

Measurement of Sound

Noise is measured in units of pressure, called decibels, named after Alexander Graham Bell, using A-weighted sound levels (dBA), which match the perception of loudness by the human ear.

How is this measured? The physics behind decibel measurement is 10 log (P2/P1) dB where the log is to base 10. To put this into context, consider this:

On the decibel scale, the smallest audible sound (near total silence) is 0 dB.

  • A sound 10 times more powerful is 10 dB.
  • A sound 100 times more powerful than near total silence is 20 dB.
  • A sound 1,000 times more powerful than near total silence is 30 dB.

Here are some common sounds and their decibel ratings:

  • Near total silence – 0 dB
  • A whisper – 15 dB
  • Normal conversation – 60 dB
  • A lawnmower – 90 dB
  • A car horn – 110 dB
  • A rock concert or a jet engine – 120 dB
  • A gunshot or firecracker – 140 dB

Considering the limits of the human body, 85-90 dB will result in hearing loss, 140 dB will cause immediate damage, and according to a study by Jurgen Altmann, 200 dB would cause your lungs to rupture.

For detailed information on this,please look at Optimum Safety Management Hearing Protection page.

NIOSH and OSHA Permissible Exposure Limits (PELs)

Now that you know how hearing works, and what it would take to kill a worker, what do you need to know about your own workplace? The National Institute for Occupational Safety and Health recommends that all worker exposures to noise should be controlled below a level equivalent to 85 dBA for eight hours to minimize occupational noise induced hearing loss.

Adopted by OSHA, permissible sound exposure levels are as follows (29 CFR 1910.95(b)(2)):

TABLE G-16 – PERMISSIBLE NOISE EXPOSURES (1)
Duration per day, hours Sound level dBA slow response
8 90
6 92
4 95
3 97
2 100
1.5 102
1 105
0.5 110
<0.25 115

 

The Average Sounds on the Job

What’s that sound? It could be OSHA knocking, if you aren’t protecting your workers from hazardous noise.

Here are some of the common sounds you or your workers may hear on the job. Compare them to the above table to see if you are adequately protecting your employees.

Carpentry Tools

Mitre Saw 102 dBA
Hand Drill 98 dBA
Chop Saw 106 dBA
Hammer Drill 114 dBA
Metal Shear 96 dBA
Hain Saw 109 dBA
Impact Wrench 102 dBA
Skill Saw 100 dBA
Belt Sander 93 dBA
Tile Saw 101 dBA
Circular Sander 90 dBA
Router 95 dBA
Planer 93 dBA
Table Saw 92 dBA
Mortissing 90 dBA

For information on the dB levels emitted by common power tools, check out the NIOSH PowerTools Database

 

Average Heavy Equipment Noise Levels

Heavy-duty bulldozer 97-107
Vibrating road roller 91-104
Light-duty bulldozer 93-101
Asphalt road roller 85-103
Laborers 78-107
Crawler crane < 35 ton (non-insulated cab) 93-101
Crawler crane >35 ton (non-insulated cab)
Crawler crane >35 ton (insulated cab)
90-98
80-89
Rubber-tired crane >35 ton (non-insulated cab)
Rubber-tired crane >35 ton (insulated cab)
78-90
59-87
Tower Crane 70-76

Source: ELCOSH

Average Construction Noise Levels

Pneumatic chip hammer 103-113
Jackhammer 102-111
Concrete joint cutter 99-102
Skilsaw 88-102
Stud welder 101
Bulldozer 93-96
Crane 90-96
Earth Tamper 90-96
Hammer 87-95
Gradeall 87-94
Front-end loader 86-94
Backhoe 84-93

Source: CPWR – Center for Construction Research and Training

Sources: Decibel Chart from Haas Eaton, OSHAX, Purdue University,

Sound Levels by Industry

Industrial Branch LAeq dB(A) LCpeak dB(C)
Foundry 93 127
Plastic packing 83 112
Metal packing 92 119
Printing press 93 119
Shipyard 92 134
Brewery 96 117
Porcelain fabric 88 128
Glass factory 95 113
Glass fibers factory 97 101
Confectionery factory 86 106
Weaving factory 95 119
Stretch factory 88 114
Paper mill 92 130
Saw mill 94 123
Copper tube factory 96 126

 

Source: World Health Organization Noise Report

Look out for part 2, featuring hearing protection advice and insights, coming soon.