A quarter of U.S. adults aged 20 to 69 have hearing loss. But it’s not just the old who suffer—the figure is 19% for people in their 20s, according to a new report by the Centers for Disease Control and Prevention (CDC). What could be the culprit? Probably not just work-related noise, like operating loud machinery, because about half of respondents said they were unaffected. CDC now plans to investigate how listening to music through earbuds or headphones might affect hearing loss, The Washington Post reports. Another surprising finding: Most people tested didn’t even realize they had a problem.