People in the study were more likely to have hearing impairment if they were of Cuban and Puerto Rican backgrounds, had a higher body mass index (an indication of being overweight), were people who snored, or had been diagnosed as having sleep apnea.
The study authors found that sleep apnea was associated with a 31 percent increase in high frequency hearing impairment and a 90 percent increase in low frequency hearing impairment. Sleep apnea was also linked to a 38 percent increase in both high and low frequency hearing loss. Speech tends to fall in the low frequency range, according to Shah.
The research is slated to be presented May 20 at the American Thoracic Society annual meeting in San Diego, Calif. Because the study has not yet been published in a peer-reviewed journal, the data and conclusions should be viewed as preliminary.
Some experts urged caution in interpreting the results of the study, however.
"The number one thing I always say is, correlation is not causation; it doesn't mean if you have sleep apnea you're at risk for hearing impairment," said Rebecca Spencer, a neuroscientist and associate professor in the department of psychological and brain sciences at the University of Massachusetts, Amherst. "You wouldn't know if one comes before the other: sleep apnea appears before hearing loss, or hearing loss appears before sleep apnea and maybe they don't come together at all. They may not be related except by a third factor."
Because a possible link has been discovered between sleep apnea and hearing loss, the next step should be a smaller study that looks more closely at the question of whether sleep apnea actually causes hearing loss, said Spencer.
She also pointed out that the data drew only from people of Hispanic and Latino descent. It would be important to look at the association between hearing loss and sleep apnea among a broader ethnic and geographical group, she added.
Only one thing can be concluded from the study, Spencer said: "There is the potential that treating sleep apnea may improve hearing loss."
Shah, the research author, said people with sleep apnea should be screened for hearing impairment since it has been shown to be associated with the disorder. "Get evaluated," she urged.