Thursday, February 12, 2009

That Buzzing Sound: Reporting & Essays: The New Yorker

I noticed the sound one evening about a year ago. At first, I thought an alarm had been set off. Then I realized that the noise—a high-pitched drone—was mainly in my right ear. It has been with me ever since. The tone varies, from a soft whoosh like a shower to a piercing screech resembling a dental drill. When I am engaged in work at the hospital or in the laboratory, it seems distant. But in idle moments it gets louder and more annoying, once even jarring me from a dream.

Tinnitus—the false perception of sound in the absence of an acoustic stimulus, a phantom noise—is one of the most common clinical syndromes in the United States, affecting twelve per cent of men and almost fourteen per cent of women who are sixty-five and older. It only rarely afflicts the young, with one significant exception: those serving in the armed forces. Tinnitus affects nearly half the soldiers exposed to blasts in Iraq and Afghanistan.

This past August, I visited the University of Buffalo, which houses one of the major clinical and research centers for the evaluation and study of tinnitus. After filling out a detailed questionnaire, I met with Christina Stocking of the Speech-Language and Hearing Clinic, who has a doctorate in audiology and specializes in the condition. Stocking thought that I might have suffered noise trauma during a youth spent on the New York City subways. Sitting in the first row of a rock concert exposes you to between a hundred and ten and a hundred and twenty decibels; the screech of the New York subways can reach about a hundred and fifteen decibels. Moreover, since much of the New York subway system is underground, the noise reverberates in the tunnels, unlike in Boston, where many of the trains are above ground and noise dissipates, or in Paris, where several metro lines run on rubber wheels.

Normally, the outer ear, known as the pinna, collects sound waves and directs them into the ear canal, which carries the sound waves to the eardrum. In turn, the eardrum vibrates, and these tremors are picked up by the three tiny bones in the middle ear: the malleus (resembling a club), the incus (shaped like an anvil), and the stapes (similar to a stirrup). These bones amplify the sound vibrations and transmit them to the inner ear, where the cochlea converts the vibrations into electrical impulses, which travel from the acoustic nerve to the part of the brain that processes sound, the auditory cortex. Tinnitus can be temporary, caused by excess wax, an infection of the inner ear, or the toxic effects of drugs like aspirin (which appears to weaken the neural signals from the ear to the brain) or those used to treat cancer. Some people with normal hearing develop spontaneous tinnitus when placed in total silence; this is believed to be a response of the auditory cortex to the abnormal absence of all ambient sounds. But the majority of people with chronic symptoms develop them in conjunction with hearing loss. With the recent proliferation of MP3 players, rates of hearing loss and tinnitus may rise sharply in the coming years. A recent European Union study has projected that as many as ten million Europeans may be at risk of developing severe hearing loss as they age; and, according to the American Academy of Audiology, noise-induced hearing loss affects about one out of every eight children in the United States.

More ...

http://www.newyorker.com.proxy1.lib.uwo.ca:2048/reporting/2009/02/09/090209fa_fact_groopman?printable=true