Noise induced hearing loss (NIHL) affects millions of worldwide. As an almost entirely preventable occupational injury, it deserves attention from employers, employees, the medical community, and occupational safety policy makers. The long term effects of hearing loss can impact the career prospects of a victim, as well as limit their quality of life personally.
There are few actions which can be taken, at present, which can remediate the long term effects of such injuries. Although current research is attempting to find medical agents which might help the ear mechanism to restore itself, this is not currently tested and approved for general use. Therefore, the most effective approach to this injury is an assiduous attention to prevention efforts. An approach using the Haddon diagram can help in visualizing where effort can be applied effectively.
IN the USA alone, some estimates suggest that there are 10-15 million with noise induced hearing loss , while other estimates suggest 1 in 30 may suffer from NIHL .
Accurate assessments are challenging because much hearing loss is age-related (presbycusis), and because the definition of what constitutes hearing loss has varied . Some 30 million Americans are estimated to be exposed to excessive noise in the workplace . The cost of this disability is estimated to be 154–186 billion dollars per year . Hearing deficits make work, education, family relations, and quality of life more challenging.
Hearing can be damaged by intensity, frequency, and duration of sound. Sound frequencies that are capable of damaging hearing range from 3,000 to 6,000 Hertz. Damaging intensity of sound pressure (called loudness), as expressed in decibels, starts at 85 dBs Higher decibel levels create damage in shorter periods of time.
Thus, an acute ‘dose’ of very loud noise, for example from an explosion, delivers the same amount of damage in a few seconds as many hours in much lower noise levels. What makes noise so pernicious is that even ‘tolerable’ noises can cause damage over the long run .1
The mechanism of NIHL, although not fully understood, is cell damage to the tiny cilia of cochlear cells. No effective remedy is yet available although research is underway into substances such as LY-411575 that hold the promise of stimulating the regrowth of these cells . Meanwhile, prevention is the most effective route for employers and workers to emphasize.
To prevent NIHL, a Haddon diagram can help to articulate the points in time and process when intervention is possible .i The Haddon Matrix treats injury like a disease, identifying the host, a vector, and the surrounding environment, at three points in time – before, during, and after the event . For hearing injuries, the best opportunities focus on prevention.
The workplace can reduce the exposure to damaging noise through human behavior changes, design and purchasing choices, and social and physical environmental modification. Training, clear rules regarding use of ear protection, reminders, monitoring for, and enforcement of, infractions, all could affect the human aspect of prevention.
Selecting the quietest available machinery, installing it in sound-dampening work spaces, or using in the open air, where sound reflection is minimized, are ways to affect the equipment aspects of the pre-event time period. Creation of a corporate culture of prevention, installing sound insulation, and providing spaces separate from the noise all could contribute to creating social and physical environments that prevent NIHL.
Hearing loss affects all aspects of an individual’s life, from work to family, to appreciation of the world around them. Because so little can be done to repair the damage after the fact, efforts at reducing the wide impact of NIHL must be concentrated on preventing the actual damage throughout the workplace. The use of a Haddon diagram can assist in visualizing all the proactive and responsive actions that can be taken to prevent NIHL.
Reference List
Alberti, P. W. (1992). Noise induced hearing loss. British Medical Journal, 304(6826), 522. Web.
Barnett, D. J., Balicer, R. D., Blodgett, D., Fews, A., Parker, C. L., & Links, J. M. (2005). The Application of the Haddon Matrix to Public Health Readiness and Response Planning. Environ Health Perspectives, 113(5), 561–566. Web.
Bloudoff-Indelicato, M. ( 2013). Hear-Raising: Compound Regenerates Auditory Hair Cells, Offering a Possible Treatment for Deafness. Scientific American. Web.
Lett, R., Kobusingye, O., & Sethi, D. (2002). A unified framework for injury control: the public health approach and Haddon’s Matrix combined. Injury Control and Safety Promotikon, 9(3), 199-205. Web.
Lynch, E., & Kil, J. (2005). Compounds for the prevention and treatment of hearing loss. Drug Discovery Today, 10(19). Web.
Rabinowitz, P. (2000). Noise-Induced Hearing Loss. American Family Physician, 61(9), 2749-2756. Web.
The American Speech-Language Hearing Association. The Prevalence and Incidence of Hearing Loss in Adults. Retrieved from The American Speech-Language Hearing Association. Web.
Footnotes
1 As an added concern for employers, toxic chemicals can exacerbate the effects of noise .
i Sample Haddon Matrix for Workplace NIHL (Social and Environmental Factors have been consolidated for space considerations)