If I have trouble hearing in one ear, is it dangerous?
It can be.
Sudden deafness is fairly common, and most of the time, it's a benign problem caused by the build-up of wax in the ear canal, water in the ear, or congestion from a head cold or allergies. In these circumstances, the nerves in the inner ear are working fine, but sound doesn't get through, a situation called "conductive" hearing loss, said Dr. Steven D. Rauch, an otolaryngologist at the Massachusetts Eye and Ear Infirmary. Usually these problems resolve themselves on their own.
But sometimes sudden deafness is "sensorineural," meaning that the inner ear nerve endings are damaged, which is a genuine medical emergency. Typically, the cause of this sudden damage is an infection deep in the inner ear, said Dr. David Vernick, an otolaryngologist in private practice in Chestnut Hill. "There's a window of only about seven to 10 days to treat this. If you miss this window, you could be permanently deaf in the affected ear."
"The problem is, you can't always tell which kind of sudden hearing loss you have," said Vernick, which means if you're in any doubt, "you need to have it checked out."
There is, however, one simple test you can do at home that can give you some guidance: "Hum aloud," said Rauch. "If you hear your voice louder in the blocked ear, there is conductive hearing loss and no emergency. If you hear your voice louder in the good ear, there's sensorineural loss on the blocked side, and it is urgent that you have it evaluated and treated. In other words, when you hum, hearing your voice in the bad ear is good and hearing it in the good ear is bad."
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