NOISE-INDUCED HEARING LOSS

What is noise-induced hearing loss?1

Every day, we experience sound in our environment, such as the sounds from television and radio, household appliances, and traffic. Normally, these sounds are at safe levels that don’t damage our hearing. But sounds can be harmful when they are too loud, even for a brief time, or when they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL).

Most NIHL is caused by the damage and eventual death of inner ear hair cells. Unlike bird and amphibian hair cells, human hair cells don’t grow back. They are gone for good.

NIHL can be immediate or it can take a long time to be noticeable. It can be temporary or permanent, and it can affect one ear or both ears. Even if you can’t tell that you are damaging your hearing, you could have trouble hearing in the future, such as not being able to understand other people when they talk, especially on the phone or in a noisy room.

Regardless of how it might affect you, one thing is certain: noise-induced hearing loss is something you can prevent.

Who is affected by NIHL?

Exposure to harmful noise can happen at any age. People of all ages, including children, teens, young adults, and older people, can develop NIHL. Based on a 2011-2012 CDC study involving hearing tests and interviews with participants, at least 10 million adults (6 percent) in the U.S. under age 70—and perhaps as many as 40 million adults (24 percent)—have features of their hearing test that suggest hearing loss in one or both ears from exposure to loud noise.

Researchers have also estimated that as many as 17 percent of teens (ages 12 to 19) have features of their hearing test suggestive of NIHL in one or both ears (Pediatrics 2011, link is external), based on data from 2005-2006.

About 18 percent of adults aged 20-69 have speech-frequency hearing loss in both ears from among those who report 5 or more years of exposure to very loud noise at work, as compared to 5.5 percent of adults with speech-frequency hearing loss in both ears who report no occupational noise exposure2.

Noise-Induced Hearing Loss among Adolescents3

Note: Lower numbers are better

This chart shows the prevalence of likely noise-induced hearing loss from 2 time periods in adolescents (12–19 years). Note: I = 95% confidence interval. Data are for adolescents who have an audiometric notch in both ears signifying probable noise-induced hearing loss. Respondents were asked to select only one race prior to 1999. For 1999 and later years, respondents were asked to select one or more races. For all years, the categories black and white include persons who reported only one racial group and exclude persons of Hispanic origin. Persons of Mexican-American origin may be any race.

The 2010 target line represents the goal recommended by the Hearing Health group, which was discussed and approved by the Federal Interagency Working Group for Healthy People 2010.

 

Noise Induced Hearing Loss Among Adults4

Note: Lower numbers are better

This chart depicts the prevalence of likely noise-induced hearing loss from 2 time periods in adults (20–69 years) by race/ethnicity and sex (gender). Updated data will become available when the new NHANES 2011–2012 audiometric survey for adults is completed. Note: I = 95% confidence interval. Data are for adults who have an audiometric notch in both ears signifying probable noise-induced hearing loss. Data are age-adjusted to the 2000 standard population. Respondents were asked to select only one race prior to 1999. For 1999 and later years, respondents were asked to select one or more races. For all years, the categories black and white include persons who reported only one racial group and exclude persons of Hispanic origin. Persons of Mexican-American origin may be any race.

The 2010 target line represents the goal recommended by the Hearing Health group, which was discussed and approved by the Federal Interagency Working Group for Healthy People 2010.

What causes NIHL5?

NIHL can be caused by a one-time exposure to an intense “impulse” sound, such as an explosion, or by continuous exposure to loud sounds over an extended period of time, such as noise generated in a woodworking shop.

Recreational activities that can put you at risk for NIHL include target shooting and hunting, snowmobile riding, listening to MP3 players at high volume through earbuds or headphones, playing in a band, and attending loud concerts. Harmful noises at home may come from sources including lawnmowers, leaf blowers, and woodworking tools.

Sound is measured in units called decibels. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen.

Here are the average decibel ratings of some familiar sounds:

  • The humming of a refrigerator- 45 decibels

  • Normal conversation- 60 decibels

  • Noise from heavy city traffic- 85 decibels

  • Motorcycles- 95 decibels

  • An MP3 player at maximum volume- 105 decibels

  • Sirens- 120 decibels

  • Firecrackers and firearms- 150 decibels

Your distance from the source of the sound and the length of time you are exposed to the sound are also important factors in protecting your hearing. A good rule of thumb is to avoid noises that are too loud, too close, or last too long.

What are the effects and signs of NIHL?

When you are exposed to loud noise over a long period of time, you may slowly start to lose your hearing. Because the damage from noise exposure is usually gradual, you might not notice it, or you might ignore the signs of hearing loss until they become more pronounced. Over time, sounds may become distorted or muffled, and you might find it difficult to understand other people when they talk or have to turn up the volume on the television. The damage from NIHL, combined with aging, can lead to hearing loss severe enough that you need hearing aids to magnify the sounds around you to help you hear, communicate, and participate more fully in daily activities.

NIHL can also be caused by extremely loud bursts of sound, such as gunshots or explosions, which can rupture the eardrum or damage the bones in the middle ear. This kind of NIHL can be immediate and permanent.

Tinnitus6

Loud noise exposure can also cause tinnitus—a ringing, buzzing, or roaring in the ears or head. Tinnitus may subside over time, but can sometimes continue constantly or occasionally throughout a person’s life. Hearing loss and tinnitus can occur in one or both ears.

Sometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16 to 48 hours later. Recent research suggests, however, that although the loss of hearing seems to disappear, there may be residual long-term damage to your hearing.

Prevalence of Chronic Tinnitus: Chart

This figure shows age and sex-specific trends in chronic tinnitus, i.e., ringing, roaring, or buzzing in the ears or head that has lasted for 3 months or longer in the past year. This information was collected in household interviews conducted as part of the 1994–1995 Disability Supplement to the U.S. National Health Interview Survey; the data are self-reported and exclude proxy responses.

The overall trend with age shows a marked increase for both sexes, beginning about age 40, peaking between 65 to 79 years, and then declining after 80 years of age. Males show significantly higher rates of tinnitus (p<0.0001) compared to females. The male prevalence is consistently higher from age 40 through 79 years, with the largest differences between males and females occurring from 50 through 69 years of age. One explanation for these differences is that males are more likely to be exposed to loud environmental noise, whether through work or leisure activities. Strong associations between occupational noise exposure and tinnitus are well documented in the literature (Hoffman and Reed, 2004).

REFERENCES
1.  National Institute on Deafness and Other Communication Disorders (NIDCD) Website- Accessed June 2017. https://www.nidcd.nih.gov/health/noise-induced-hearing-loss
2.  IBID- https://www.nidcd.nih.gov/health/statistics/quick-statistics-hearing
3.  National Health and Nutrition Examination Survey, NCHS, CDC. Chart created by the Health Promotion Statistics Branch, NCHS, CDC and the Epidemiology and Statistics Program, NIDCD, NIH. Posted in November 2012, Last Updated Date: October 17, 2012. https://www.nidcd.nih.gov/health/statistics/noise-induced-hearing-loss-among-adolescents
4.  IBID- https://www.nidcd.nih.gov/health/statistics/noise-induced-hearing-loss-among-adults
5. National Institute on Deafness and Other Communication Disorders (NIDCD) Website- Accessed June 2017. https://www.nidcd.nih.gov/health/noise-induced-hearing-loss
6.  1994–1995 National Health Interview Study Disability Supplement, Chart created by the NIDCD Epidemiology and Statistics Program, November 2012.  Hoffman HJ, Reed GW. Epidemiology of tinnitus, Snow JB Jr, ed: Tinnitus: Theory and Management. Hamilton, Ontario: B.C. Decker, Inc. 2004; 16–41. Last Updated June 7, 2010. https://www.nidcd.nih.gov/health/statistics/prevalence-chronic-tinnitus-chart