Dear Lucy: In my lab, I have several pieces of noisy equipment. When they’re all operating as I run an experiment, they generate a hum of white noise that I can tune out. However, sometimes I put on noise-blocking earmuffs, and after removing them I notice that the sound is actually quite loud. (To communicate in here, one usually needs to speak loudly in close proximity to the other person—though not shout—to be heard.) I prefer not to use the earmuffs, since they pinch against the sides of my glasses. Am I in danger damaging my hearing? —Say What?
Dear Say What?: Lucy asked MIT Medical audiologist Christine Rabinowicz, C.C.C.-A., about this noisome issue, and the answer to your question is a definite “maybe.” The effects of noise on a person’s hearing depend not just on how loud the sound is, but how long it lasts and the length of time between periods of loud noise. These “recovery times” between noise exposures are an important factor in hearing loss, Rabinowicz says, “so even if you wear earplugs or earmuffs in the lab, I’d advise that you refrain from mowing the lawn or riding a motorcycle when you’re at home, to avoid causing more insult to your ears,” Rabinowicz says.
At your request, staff from the Industrial Hygiene Program, part of MIT’s Environmental Health and Safety Office, will visit your lab and measure the noise levels at different times. If they find your noise exposure is above a time-weighted average of 85 decibels for an eight-hour day, you’ll be required to use hearing protection supplied by MIT and have annual exams with Rabinowicz to monitor your hearing. “There are several types of hearing-protection devices available, including ear plugs and ear inserts as well as earmuffs, so if your earmuffs are uncomfortable, try something else until you find something you like and that’s effective for your noise environment,” Rabinowicz says. (She can also send you a brochure about hearing protection; call 617-253-7870.)
Some hearing loss is normal as you age, Lucy reminds everyone, even for those of us whose rock concert days are over. That makes it even more important to safeguard your hearing now so you’ll be as sharp-eared as possible in your later years. —Lucy