IMPORTANCE As the US population ages, effective health care planning requires understanding the changes in prevalence of hearing loss. OBJECTIVE To determine if age-and sex-specific prevalence of adult hearing loss has changed during the past decade. DESIGN, SETTING, AND PARTICIPANTS We analyzed audiometric data from adults aged 20 to 69 years from the 2011-2012 cycle of the US National Health and Nutrition Examination Survey, a cross-sectional, nationally representative interview and examination survey of the civilian, noninstitutionalized population, and compared them with data from the 1999-2004 cycles. Logistic regression was used to examine unadjusted, age-and sex-adjusted, and multivariable-adjusted associations with demographic, noise exposure, and cardiovascular risk factors. Data analysis was performed from April 28 to June 3, 2016. INTERVENTIONS Audiometry and questionnaires. MAIN OUTCOMES AND MEASURES Speech-frequency hearing impairment (HI) defined by pure-tone average of thresholds at 4 frequencies (0.5, 1, 2, and 4 kHz) greater than 25 decibels hearing level (HL), and high-frequency HI defined by pure-tone average of thresholds at 3 frequencies (3, 4, and 6 kHz) greater than 25 decibels HL. RESULTS Based on 3831 participants with complete threshold measurements (1953 men and 1878 women; mean [SD] age, 43.6 [14.4] years), the 2011-2012 nationally weighted adult prevalence of unilateral and bilateral speech-frequency HI was 14.1%(27.7 million) compared with 15.9%(28.0 million) for the 1999-2004 cycles; after adjustment for age and sex, the difference was significant (odds ratio [OR], 0.70; 95% Cl, 0.56-0.86). Men had nearly twice the prevalence of speech-frequency HI (18.6%[17.8 million]) as women (9.6%[9.7 million]). For individuals aged 60 to 69 years, speech-frequency HI prevalence was 39.3%( 95% Cl, 30.7%-48.7%). In adjusted multivariable analyses for bilateral speech-frequency HI, age was the major risk factor (60-69 years: OR, 39.5; 95% Cl, 10.5-149.4); however, male sex (OR, 1.8; 95% Cl, 1.1-3.0), non-Hispanic white ( OR, 2.3; 95% Cl, 1.3-3.9) and non-Hispanic Asian race/ethnicity (OR, 2.1; 95% CI, 1.1-4.2), lower educational level ( less than high school: OR, 4.2; 95% Cl, 2.1-8.5), and heavy use of firearms (>= 1000 rounds fired: OR, 1.8; 95% Cl, 1.1-3.0) were also significant risk factors. Additional associations for high-frequency HI were Mexican-American (OR, 2.0; 95% Cl, 1.3-3.1) and other Hispanic race/ ethnicity (OR, 2.4; 95% CI, 1.4-4.0) and the combination of loud and very loud noise exposure occupationally and outside of work ( OR, 2.4; 95% CI, 1.4-4.2). CONCLUSIONS AND RELEVANCE Adult hearing loss is common and associated with age, other demographic factors (sex, race/ ethnicity, and educational level), and noise exposure. Age-and sex-specific prevalence of HI continues to decline. Despite the benefit of delayed onset of HI, hearing health care needs will increase as the US population grows and ages.