Many people are exposed to dangerously loud sounds at work and at play, and most of them don't wear ear plugs or take other steps to prevent hearing loss, a recent U.S. study suggests.

Almost 49 million adults work in very noisy conditions, and more than one-third of them never use hearing protection, the study found. Among leisure pursuits, firearms pose a particular risk and just 59 percent of the 35 million U.S. gun users represented in the study wear hearing protection all the time.

"The problem here is both the number of people using firearms and the potential noise-inducing hearing loss from the repeated gunfire," said senior study author Dr. Neil Bhattacharyya of Harvard Medical School and Brigham and Women's Hospital in Boston.

"A rifle has an extremely loud single burst of sound and if you are firing hundreds of rounds, that can be very damaging, particularly without hearing protection," Bhattacharyya said by email.

To assess how often U.S. adults are exposed to loud noise and how regularly they take steps to protect against hearing loss, researchers examined 2014 survey data representing 240 million people.

Overall, 22 percent were exposed to “very loud” sounds at work requiring them to shout to be heard at arm’s length. The exposures were for at least four hours a day, several days a week.

Roughly one in five people were exposed to loud sounds outside of work, and 62 percent of them didn't use hearing protection, researchers report in The Laryngoscope.

With firearms, researchers found that one in five people who shot more than 10,000 rounds of ammunition in the past year never used hearing protection. Most of the firearm-related noise exposure came during recreational shooting.

Lawn mowers were the most common source of non-occupational noise exposure.

Almost two-thirds of people around loud noises during recreational activities never used any hearing protection.

One limitation of the study is that it only included one year of survey data, the authors note. It also didn't have medical records to document specific hearing or health problems associated with noise.

"Untreated hearing loss is associated with increased stress, depression and social withdrawal, and may exacerbate problems for those with cognitive changes such as dementia," said Dr. Jennifer Derebery of the House Ear Clinic and Institute and the University of California Los Angeles David Geffen School of Medicine.

If people aren't sure whether the noise around them is loud enough to damage their ears, they can get a sound meter app for their phone and use ear plugs or other protection whenever the app shows the sound is too loud, Derebery, who wasn't involved in the study, said by email.

And there are good options for people to wear when they still need to hear the sounds around them, a concern for many hunters and concert goers.

"There are outstanding electronic ear muff and ear plug options that solve many of the complaints that recreational shooters and hunters have related to conventional hearing protection," said Colleen Le Prell, an audiology researcher at the University of Texas at Dallas who wasn't involved in the study.

"They allow quiet sounds, such as speech and sounds the hunter might be making as they walk, to be not only delivered but amplified, which can be very useful with someone who already has some hearing loss," Le Prell said by email. "Hearing loss can be prevented, with the consistent and correct use of hearing protection devices."