Overview:

This article provides a general overview of the structure of the ear and the definition of noise and discusses the importance of protecting the ears from damaging noise. Hearing conservation issues are discussed with regard to employer responsibilities, including training, providing personal protective equipment and conducting hazard assessments. A noise hazard analysis checklist is provided to assist the agency with locating high noise equipment and processes. Links for resources are included for safety officers to communicate to employees.

What Is Noise And How Does It Affect The Worker?

While the interpretation of noise may lie in the “ears of the beholder” when it comes to music, talking and other audible sounds, the definition is quite clear. Noise is any sound that is excessively loud, unpleasant, unexpected or undesired. It has been described as the most pervasive pollutant in America. Because we use mechanical or industrial processes everywhere, noise is often created in the process. Exposure to high noise levels (85 decibels or greater), while unprotected and for extended periods can result in gradual but permanent hearing loss. Other effects include: decreased job performance, increased fatigue and irritability. According to the National Institute on Deafness and Other Communication Disorders, more than 30 million Americans are exposed to hazardous sound levels on a regular basis.

How Does The Ear Work?

The ear is composed of three sections: the outer ear, the middle ear and the inner ear. Hearing loss occurs when the chamber in the inner ear, the cochlea, is damaged. The cochlea is filled with tiny, fluid-filled hair cells. As the hairs are damaged by harsh, loud noises, they weaken in their ability to “bounce back” or recover. Once damaged, the hairs do not regenerate and adversely affect the ability to hear. For this reason, hearing protection is of the utmost importance.

How Can You Tell If Noise Being Created Is Hazardous?

The amount of noise and the length of time exposed to the noise determine potential hearing damage. Noise is measured in decibels (dB). The chart below provides examples of the types of noise and decibel levels we are exposed to daily in the workplace. This list can be used as a checklist to locate potentially hazardous noise areas and activities within the workplace.

· 40dB quiet office, library
· 50 dB large office
· 65 – 95 dB power lawn mower
· 80 dB manual machine, tools
· 85 dB handsaw
· 90 dB tractor
· 90 – 115 dB subway
· 95 dB electric drill
· 100 dB factory machinery
· 100 dB woodworking class
· 105 dB snow blower
· 110 dB power saw
· 110 dB leaf blower
· 120 dB chain saw, hammer on nail
· 120 dB pneumatic drills, heavy machine
· 120 dB jet plane (at ramp)
· 120 dB ambulance siren
· 125 dB chain saw
· 130 dB jackhammer, power drill
· 130 dB air raid
· 130 dB percussion section at symphony
· 140 dB airplane taking off
· 150 dB jet engine taking off
· 150 dB artillery fire at 500 feet
· 180 dB rocket launching from pad

Warning Signs of Hazardous Noise Exposure

Some warning signs that indicate that you may have been exposed to hazardous noise levels are:

• You have to speak louder than normal while in the area and after leaving the area
  
• You cannot hear when someone is standing close to you (two feet or closer)
  
• After leaving a noisy area, speech sounds muffled
  
• After leaving a noisy area, your ears hurt or you experience ringing.
  

The best way to protect hearing is by preventing exposure to high noise levels. If it is not possible to prevent the exposure to a hazardous area, there are some alternate methods of protection available.

• Use proper hearing protection
  
  
  
  • Earplugs- devices placed directly in the ear canal causing a block in the canal. By using earplugs, the noise can be reduced by 15-30 dB.
    
  • Ear muffs- devices placed completely over the ears blocking sound from the entire ear. By using ear muffs, the noise can be reduced by 15-30 dB.
    
  • Plain cotton- is not an acceptable hearing protection device. Cotton only reduces noise by approximately 5-7 dB.
    

• Limit periods of exposure to noise
  
  
  
  • When an employee’s exposure to noise reaches 85 dB or greater in an 8-hour period, a hearing conservation program must be developed according to OSHA 29 CFR 1910.95. Limiting the number of hours an employee is exposed to noises 85 dB or greater and allowing employees to rotate in and out of the area to rest their ears may prevent long-term damage to employee hearing. This should be done in conjunction with providing adequate hearing protection.
    
  
  
• Education
  
  
  
  • Educate employees about the dangers of working in high noise areas without proper protection. Also point out the areas of concern and utilize safety signs so that all employees are aware of the potential hazards. Lead by example by following all precautions while in high noise areas.
    
  
  
• Have regular hearing tests
  
  
  
  • If employees regularly work in high noise areas, have annual hearing tests done by a certified audiologist, otolaryngologist or other physician or by a technician certified by the Council of Accreditation in Occupational Hearing Conservation.
    

What Is the Employer’s Responsibility?

The employer is responsible for protecting employees from disabling hearing loss by providing:

• Training annually on
  
  
  
  • The effects of noise on hearing;
    
  • The purpose of hearing protectors, advantages, disadvantages, instructions on selection, fitting, use and care;
    
  • The purpose of audiometric testing and an explanation of the process.
    
  
  
• Audiometric Testing
  
  
  
  • Annually, at no cost to the employee.
    
  
  
• Personal Protective Equipment
  
  
  
  • Ear plugs;
    
  • Ear muffs.
    
  
  
• Noise Monitoring
  
  
  
  • When there is an indication that the employee will be exposed to 85 dB or more in an 8-hour period;
    
  • When a change in production, process, equipment or controls increases noise exposures;
    
  • When the selected hearing protection becomes inadequate.
    

Links:
Noise Hazard Assessment Worksheet
http://www.covwc.com/docs/Noise_Hazard_Assessment.pdf

League for the Hard of Hearing
http://www.lhh.org/noise/decibel.htm

OSHA 29 CFR 1910.95 Occupational Noise Exposure
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9735

NIOSH Hearing Conservation Program Evaluation Checklist http://www.cdc.gov/niosh/hpprgmch.html

OSHA Hearing Conservation Informational Booklet
http://www.osha.gov/Publications/osha3074.pdf