Teens at Risk: “We’re on the Edge of an Epidemic” Research on Hearing Loss Has Long-term Implications for Audiologists Features
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Features  |   September 01, 2010
Teens at Risk: “We’re on the Edge of an Epidemic”
Author Notes
  • Marat Moore, is the managing editor of The ASHA Leader, can be reached at mmoore@asha.org.
    Marat Moore, is the managing editor of The ASHA Leader, can be reached at mmoore@asha.org.×
Article Information
Hearing Disorders / Features
Features   |   September 01, 2010
Teens at Risk: “We’re on the Edge of an Epidemic”
The ASHA Leader, September 2010, Vol. 15, 1-38. doi:10.1044/leader.FTR4.15112010.1
The ASHA Leader, September 2010, Vol. 15, 1-38. doi:10.1044/leader.FTR4.15112010.1
Research on teen hearing loss published in the Aug. 18 issue of the Journal of the American Medical Association (JAMA) has implications for audiologists in the short term and in the decades to come.
In “Change in Prevalence of Hearing Loss in U.S. Adolescents” (JAMA, Aug. 18, 2010), researchers showed that teen hearing loss overall jumped 31% from 1988–1994 to 2005–2006, and for mild and worse cases, spiked 77% over the same period (see p. 4 sidebar for definitions of these categories and a research summary).
The study showed one in five U.S. adolescents 12 to 19 years old—approximately 6.5 million teens—had hearing loss in 2005–2006.
In this multipart series, upcoming articles will feature the views of audiologists on the implications of this research, strategies to prevent further erosion of hearing health, and resources to help combat the problem.
“We’re on the edge of an epidemic, and we want to do everything we can to stop it,” said Roland D. Eavey, one of the four authors and director of the Bill Wilkerson Center and chair of the Department of Otolaryngology at the Vanderbilt University School of Medicine in Nashville.
Eavey said he was startled that hearing loss in this population rose so steeply in such a short time. “Prevalence went way up. In mild and worse cases, it’s nearly doubled in less than a generation,” he said.
Audiologists predicted this trend, said Tena McNamara, president-elect of the Educational Audiology Association (EAA), whose members are in the schools but in numbers too small to address the issue fully.
“We knew this was coming—and now we have the evidence. We need to find a way to collaborate to help prevent further hearing losses,” she said, adding that all audiologists, with the help of school-based speech-language pathologists, should become involved in a broad education campaign on the issue.
The release of the research ignited a media storm on the risk of listening to high-volume music delivered directly into the ear canal through iPods and MP3 players, although the study does not determine causality.
When the story broke, ASHA was ready—not just to respond to the barrage of media requests and to help line up interviews for audiologists, but to point to its longstanding “Listen to Your Buds” public awareness campaign and the list of ASHA journal articles published on the use of MP3 players.
NBC and ABC interviewed ASHA President Tommie L. Robinson, Jr., and the coverage was aired by dozens of affiliates nationwide. Audiology researchers and clinicians were interviewed widely as well, and researcher Brian Fligor—who has published in ASHA’s Journal of Speech, Language, and Hearing Research and elsewhere on the hearing health impact of MP3 players—appeared on CBS Evening News.
A Kaiser Family Foundation report [PDF] released in January showed that the time youths spend using personal entertainment technology has increased dramatically in the last five years—to an average of more than 7.5 hours per day for individuals age 8 to 18. That average increases to 10 hours and 45 minutes when media multi-tasking is taken into account.
Eavey said the research team welcomed the publicity. “Whether future research shows that MP3 players are a cause or instead are part of a complex pattern, this is something we can work on,” he said.
“Unlike genetic hearing loss, MP3 players are a modifiable risk factor,” he said. “The next step is researching in large populations what might be causing this hearing loss.”
“Change in Prevalence of Hearing Loss in U.S. Adolescents”: A Summary of the Research

The study examined two comparable databases from two time periods within the last 20 years to determine whether the current prevalence of teen hearing loss in the United States had changed over time, and to assess characteristics of hearing impairment in the 12- to 19-year-olds.

The two data sources were the Third National Health and Nutrition Examination Survey (NHANES III), which examined 2,928 participants aged 6 to 19 years between 1988 and 1994; and NHANES 2005–2006, which examined 1,771 participants aged 12 to 19 years. The NHANES studies include physical examinations and interviews.

The results are based on audiometric assessment and comparison of high- and low-frequency pure-tone averages. Researchers looked at the prevalence of hearing loss (any, low-frequency, high-frequency, unilateral, and bilateral hearing loss of slight or mild-or-greater intensity). The study controlled for race/ethnicity and socioeconomic status, and examiners were trained by a certified audiologist at the National Institute of Occupational Safety and Health.

Audiometric Measures

Audiometric measures, definitions of hearing loss, and methods of participant selection were consistent in both NHANES survey cycles. The low-frequency pure tone average (LPTA) was obtained by the average of air conduction pure-tone thresholds at 0.5, 1, and 2 kHz and the high-frequency PTA (HPTA) was obtained by the average of air conduction pure-tone thresholds at 3, 4, 6, and 8 kHz. Low-frequency and high-frequency hearing loss were characterized as either unilateral or bilateral.

Measures of hearing loss were categorized more finely according to the hearing sensitivity in the worse ear and defined as:

  • Any hearing loss (LPTA or HPTA >15 dB)

  • Slight hearing loss (LPTA or HPTA between 15 dB and 25 dB)

  • Mild or worse hearing loss (LPTA or HPTA of 25 dB or greater)

A noise-induced threshold shift (NITS) was defined as an audiogram pattern that showed a 15 dB or greater notch in the high frequencies.

Major Points

Among the major points outlined in the JAMA article:

  • The prevalence of any hearing loss in participants increased 31%, from 14.9% in 1988–1994 to 19.5% in 2005–2006.

  • The majority of the hearing loss in 2005–2006 was slight, but the prevalence of mild or worse hearing loss increased 77% from 3.5% in 1988–1994 to 5.3% in 2005–2006.

  • The prevalence of high-frequency hearing loss was significantly higher in 2005–2006 than in the earlier study, but the prevalence of low-frequency hearing loss was not.

  • The prevalence of unilateral hearing loss was 11.1% in 1988–1994 and 14% in 2005–2006; in both time periods, it was more common than bilateral hearing loss, but “the reasons are unknown,” according to the study.

  • High-frequency hearing loss was more common than low-frequency hearing loss in both time periods.

  • The prevalence of hearing loss did not significantly differ by age or race/ethnicity in either time period.

  • The study found no difference in estimated noise exposure between the two survey cycles. There also was no significant association between self-reported noise exposure and hearing loss in 2005–2006. However, the authors noted that “adolescents and young adults typically underestimate symptoms of loud sound, tinnitus, and temporary hearing impairment during music exposure and underreport these conditions.”

  • Participants reporting an income below the national poverty level had significantly increased risk of hearing loss in 2005–2006 but not in the earlier survey. The authors noted that the association with income is consistent with past literature, but the mechanisms are “unclear” and are not linked to untreated middle-ear disease, as the data were adjusted for that factor.

  • Females were significantly less likely to demonstrate any hearing loss than males and less likely to demonstrate high-frequency hearing loss.

  • The prevalence of noise-induced threshold shifts (NITS) was similar in both survey cycles. Authors noted that NITS as defined in these studies may not be as reliable as a higher PTA in the high-frequency range, which may be a more reliable marker of noise-induced hearing loss.

The researchers noted that definitions of hearing loss have not been standardized among investigators, and that previous studies have employed maximal threshold levels ranging from 15 dB to 25 dB to define normal hearing. Definitions of low- and high-frequency hearing loss also have varied, “with some controversy as to the placement of the 2 kHz frequency.” In this study, the 2 kHz frequency has been included in the low-frequency category and the 15 dB threshold has been used as the maximal threshold for normal hearing, as this measurement has been used more consistently to define hearing loss in studies of children and young adults.

The authors cautioned that the prevalence and extent of hearing loss may be underestimated because of an under-sampling of children with known hearing loss, who could not always be tested. Due to the study’s cross-sectional methodology, causality related to risk factors could not be determined. They cited the need for further research to determine the reasons for this dramatic increase in hearing loss and to identify potential “modifiable risk factors” to stem this epidemic.

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September 2010
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