Q. I'm in my 80s and have been progressively losing my hearing. When I asked my doctor what caused my hearing loss, he said it was because my "cochlea died." What did he mean?
A. The cochlea is a spiral-shaped structure inside your ear. It contains the hair cells that transmit sound messages to the brain. Sounds are composed of invisible waves. When a sound wave enters your ear, it moves the hairs on the hair cells just as a summer breeze moves the leaves on a tree. When the hairs on the hair cells move, they send a signal to the brain. The brain then "hears" and interprets the sound.
Most hearing loss results from the destruction of the sensory hair cells in the cochlea. When your doctor said that your cochlea "died," he was referring to the death of these cochlear sensory cells. Hearing loss caused by the death of cochlear hair cells is usually permanent.
So what causes these cells to die? For one thing, the very process of aging. Over time, some hair cells in the inner ear grow old and die, and they are not replaced. As a result, the signals they normally send to the brain are weakened.
Also, over a lifetime, cumulative exposure to loud noise gradually damages and kills these hair cells. This leaves fewer cells to respond to sounds.
Sudden hearing loss can occur when these cells are destroyed by an extremely loud noise, such as an explosion. The extent of damage depends on the loudness of the noise and how long it lasts. It also depends on your sensitivity to the ill effects of loud sounds.
Spending a night at a loud rock concert can cause temporary hearing loss that lasts for several hours or several days. But going to loud concerts on a regular basis can cause cumulative damage to hair cells that leads to permanent hearing loss.
We have more information on the causes of hearing loss in our Special Health Report, "Hearing Loss." Learn more about this report at AskDoctorK.com, or call (877) 649-9457 toll-free to order it.
More often than not, however, the noise that destroys cochlear cells is not one deafening bang. Rather, it's decades' worth of exposure to the high-decibel noises of daily life. The culprits include leaf blowers, cars honking, highway traffic, movie theater sounds, hair dryers, vacuum cleaners and loud music. We probably have more noise in our lives than most of our great-grandparents and their forebears did.
Fortunately, I can offer my patients hearing aids that are much better than they used to be. They hear sound better, and they are much smaller and lighter. But if, as your doctor said, your "cochlea has died," hearing aids may not offer much help.
However, today we also have a whole new technology called cochlear implants. These devices can restore hearing in many people for whom hearing aids no longer work. An ear, nose and throat physician working with an audiologist can tell you the options that are likely to work best for you.
• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: AskDoctorK.com.