Most hearing conservation programs rely on hearing protection devices (HPDs) to reduce workers’ exposure to hazardous noise and other loud sounds and to prevent noise-induced hearing loss (NIHL). Other methods of reducing noise exposure, such as engineering and administrative controls, are used less often due to enforcement policies that allow hearing protectors to be used as a substitute for noise controls and because of concerns about the effectiveness and feasibility of noise controls in the workplace.
Many individuals who understand the importance of hearing protection are still misinformed about both the factors that influence how well HPDs work and the behaviors and beliefs that can result in less protection. For this reason, I’d like to draw your attention to five of the most common hearing protection myths and review the evidence that disproves them.
1 Myth: All foam earplugs are about the same.
TRUTH: Despite the fact that most foam earplugs are designed to be rolled into a small cylinder and inserted into the ear canal where they expand to form a noise-blocking barrier, foam earplugs vary widely in terms of size, shape, recovery time, softness when touched, easeof- insertion, pressure and the degree to which they are affected by moisture and humidity. These properties influence how easy it is to properly fit an earplug and how comfortable the earplug is to wear.
If an earplug expands too quickly (short recovery time) or is difficult to push into the ear canal (not rigid enough) the wearer might not insert the earplug far enough to work correctly. Likewise, earplugs that are too big or those that exert excessive pressure in the ears may feel uncomfortable, causing the user to wear them incorrectly or to wear them less often than necessary. The end result is a dramatic reduction in effective protection as shown in Figure 1.
2 Myth: Custom earplugs provide more noise reduction than other earplugs.
TRUTH: The protection provided by custom HPDs may vary over time due to subtle changes in the ear canal shape and the condition of the earplugs. While non-custom earplugs rely on expanding foam or flexible flanges to form a noise-blocking seal in the ear canal, custom earplugs must fit tightly and fill the ear canal space very precisely to create the necessary acoustic seal. Small changes in the shape or fit of a custom-molded earplug or movement of the device in the ear canal may result in an acoustic leak that allows more noise to bypass the earplug.
3 Myth: I don’t need to wear hearing protection. I’ve been working around noise for years with no problem.
TRUTH: People who tolerate loud sounds without discomfort are just as likely to develop NIHL as those who are uncomfortable in noisy situations. In other words, the risk of damaging your hearing after exposure to loud sounds is unrelated to your physical or mental “toughness.” Despite the fact that some people appear to be more susceptible to NIHL than others, the only sure way to lower the risks associated with excessive noise exposure is to limit the level of noise to which you are exposed and the length of time of exposure. Ultimately, behavior has a much bigger impact on hearing protection than stamina, strength or other similar physical characteristics.
4 Myth: The most important predictor of protection provided by a hearing protector is the Noise Reduction Rating (NRR.)
TRUTH: First of all, for nearly all noise exposures, the comfort of the hearing protector is a far more important factor than the NRR in predicting how much protection a device will provide simply because comfort has a greater influence on how long the device is worn and whether it is worn properly.1 Ultimately, those two factors, wear time and proper fit, play a much greater role in determining the amount of protection provided.2
Secondly, OSHA has estimated that approximately 90 percent of workers in the United States have average daily noise exposures of 95 dBA or less.3 This suggests that 9 out of 10 workers need only10 dB of protection to bring their TWA noise exposures down to or below 85 dBA, the noise exposure limit recommended by NIOSH, ACGIH and numerous other occupational health and safety organizations.
When worn properly, most well-designed hearing protectors are capable of providing 10 dB or more of protection, regardless of the NRR. Employers would do well to provide a variety of devices from which employees may choose and to encourage employees to carefully select the device that both fits well and is comfortable to wear.
5 Myth: Hearing loss is no big deal; I’ll just get hearing aids so I can hear like I always did.
TRUTH: Although eyeglasses can, in most cases, correct vision to nearly normal, hearing aids cannot do likewise for noise-induced hearing loss. Correctable vision problems generally result from ocular distortions rather than from damage to the sensory cells in the eye. NIHL, on the other hand, is due to destruction of the sensory cells in the inner ear, known as “hair cells,” that are essential to normal hearing. While hearing aids can improve detection and discrimination of sounds, they cannot restore “normal hearing” because the sensory cells required to process the amplified sound are not functional.
And it’s hard to imagine that persons who object to wearing hearing protectors eight hours a day will be willing to wear hearing aids (which feed sound into the ears through earplug-like devices) every day for the rest of their lives.4
The good news is that when fitted and worn correctly, hearing protectors are effective at reducing noise exposure. Despite the prevalence of hearing protection myths, there is a wealth of accurate information available from many different sources online and in print.
1. Arezes, P. M. and Miguel, A. S. (2002). Hearing Protectors; Acceptability in Noisy Environments. Ann. Occup. Hyg. 46(6), 531-536.
2. Berger, E. H. (2000). Hearing Protection Devices. In E.H. Berger, L.H. Royster, J.D. Royster, D.P. Driscoll, and M. Layne (Eds.), The Noise Manual, 5th Edition. Am. Ind. Hyg. Assoc., Fairfax, VA, 379-454.
3. “Occupational Noise Exposure; Hearing Conservation Amendment,” Occ. Safety and Health Admin., Federal Register., Vol. 46, No. 11, p. 4109, January 16, 1981.
4. Berger, E.H. EARLog #9 - Responses to Questions and Complaints Regarding Hearing and Hearing Protection(Part II). Retrieved from http://www.E-A-R.com/hearingconservation