BOSTON (CBS) — Boston Marathon bombing survivors are dealing with a multitude of health problems — many of them obvious, such as lost limbs.

But others are not so obvious. Quite a few survivors, like Heather Abbott, are also coping with serious hearing loss.

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“I struggle to hear what people are saying,” Abbott tells CBS News. “And sometimes I’ll ask them to repeat themselves so many times that I just pretend I’ve heard at a certain point.”

The April 2013 bombings left more than 100 with an ear injury or hearing loss, and many are participating in a three-year study at the Massachusetts Eye and Ear Infirmary.

Much of the past research in the field studied soldiers injured on the battlefield.

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“This was, of course, in a crowded group of spectators who weren’t wearing headgear or helmets and so thinking about that in terms of blast mechanics, and how pressure waves ricochet off of buildings, surroundings are very important in terms of how much damage is actually done,” researcher Dr. Alicia Quesnel said.

Abbott had to wait a year for her ruptured ear drum to heal before she could get hearing aids.

Marathon bombing survivor Heather Abbott struggles with hearing loss (Image credit CBS News)

Marathon bombing survivor Heather Abbott struggles with hearing loss (Image credit CBS News)

“I definitely hear voices louder and clearer and background noises that I don’t hear when they’re off,” she said.

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Now, Abbott hopes the study will lead to better technology the same way other research led to the prosthetic that makes it possible for her to run again. She has also started her own foundation to help trauma victims get prosthetics.