There were significant changes in health and lifestyle throughout the 20th century which may have changed temporal patterns of hearing impairment in adults. In this study, the authors aimed to assess the effect of birth cohort on the prevalence of hearing impairment in an adult population aged 45-94 years, using data collected between 1993 and 2008 from 3 cycles of the Epidemiology of Hearing Loss Study (n = 3,753; ages 48-92 years at baseline) and a sample of participants from the Beaver Dam Offspring Study (n = 2,173; ages > or =45 years). Hearing impairment was defined as a pure-tone average of thresholds at 0.5, 1, 2, and 4 kHz greater than 25-dB HL [hearing level]. Descriptive analysis, generalized additive models, and alternating logistic regression models were used to examine the birth cohort effect. Controlling for age, with every 5-year increase in birth year, the odds of having hearing impairment were 13% lower in men (odds ratio = 0.87, 95% confidence interval: 0.83, 0.92) and 6% lower in women (odds ratio = 0.94, 95% confidence interval: 0.89, 0.98). These results suggest that 1) older adults may be retaining good hearing longer than previous generations and 2) modifiable factors contribute to hearing impairment in adults.

Associations between long-term serum C-reactive protein levels and incident hearing impairment were observed in the cohort as a whole, but differed significantly by age group, with statistically significant associations observed in adults less than 60 years, participants moving through the peak risk period for hearing impairment over the course of the study.

Objective To identify factors contributing to the declining prevalence of hearing impairment in more recent generations. Methods We used data on hearing thresholds and potential risk factors of hearing impairment collected from studies in Beaver Dam, Wisconsin, the Epidemiology of Hearing Loss Study (1993-1995, n = 3,753; 1998-2000, n = 2,800 and 2003-2005, n = 2,395), the concurrent Beaver Dam Eye Study on the same cohort, and a subgroup (n = 2,173) of the Beaver Dam Offspring Study (2005-2008). Results Educational attainment significantly reduced the odds ratio (OR) of the birth cohort effect on hearing impairment from 0.90 to 0.93, while a history of ear infection had a reverse effect on the decreasing trend (significantly changing the OR from 0.93 to 0.94). Occupational noise exposure, smoking, and a history of cardiovascular disease, while associated with hearing impairment, did not attenuate the cohort effect. The cohort effect remained significant after known risk factors were adjusted (OR = 0.93; 95% confidence interval, 0.89-0.97). Conclusion These data provide strong evidence that environmental, lifestyle, or other modifiable factors contribute to the etiology of hearing impairment and add support to the idea that hearing impairment in adults may be prevented or delayed.

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Objectives Recent research suggests that hearing impairment is declining among older adults compared to earlier generations of the same age. Tinnitus is often associated with hearing impairment, so one might hypothesize that the prevalence of tinnitus is declining in a similar manner. The purpose of this study was to utilize multi-generational data with repeated measures to determine if the prevalence of tinnitus is declining among more recent generations. Design Using data from the Epidemiology of Hearing Loss Study (1993-95, 1998-00, 2003-05, 2009-10) and the Beaver Dam Offspring Study (2005-08), we examined birth cohort patterns in the report of tinnitus for adults aged 45 years and older (n=12,689 observations from 5,764 participants). Participants were classified as having tinnitus if they reported tinnitus in the past year of at least moderate severity or that caused difficulty falling asleep. A low-frequency (500, 1000, and 2000 Hz) and high-frequency (3000, 4000, 6000, 8000 Hz) pure tone average from the worse ear were used to summarize hearing status. Other potential risk factors for tinnitus were also explored to determine if changes in the prevalence of these factors over time could explain any observed birth cohort differences in the prevalence of tinnitus. These included: education, history of head injury, history of doctor-diagnosed ear infections, history of cardiovascular disease (myocardial infarction, stroke or angina), current noisy job, longest-held job, target shooting in the past year, number of concerts ever attended, alcohol use in the past year, doctor-diagnosis of arthritis, current aspirin use, regular exercise, and consulting with a physician in the past year about any hearing/ear problem. Birth cohort effects were modeled with alternating logistic regression (ALR) models which use generalized estimating equations to adjust for correlation among repeated measurements over time that are nested within families. Results The report of tinnitus tended to increase with more recent birth cohorts compared to earlier birth cohorts. For example, at ages 55-59 years, 7.6% of participants born in 1935-39 reported tinnitus, compared to 11.0% of those born in 1940-44, 13.6% of those born in 1945-49, and 17.5% of those born in 1950-54. Similarly, at ages 65-69 years, 7.9% of participants born in 1925-29 reported tinnitus, compared to 10.0% of those born in 1930-34, 11.9% of those born in 1935-39, and 13.7% of those born in 1940-44. Final ALR model results indicated that, on average, after adjusting for age and other factors, participants in a given generation were significantly more likely to report tinnitus than participants from a 20-year earlier generation (Odds Ratio = 1.78, 95%CI = 1.44, 2.21). Conclusions Increased reports of tinnitus may reflect increased prevalence of symptoms, increased awareness of symptoms, or higher health expectations among more recent generations of adults. Regardless of the reasons, the increasing prevalence of tinnitus suggests that health care providers may s...