"Teachers were indicating that she had ADD and I just didn't believe that was true," said Brooklyn's mom Susan Miller.
She was right; her daughter actually had a mild hearing loss.
A new report in the Journal of the American Medical Association suggests one out of 20 students has a hearing impairment like Brooklyn's, and one out of five have some evidence of hearing loss.
Dr. John House, president of the House Ear Institute and clinical professor of otolaryngology at USC School of Medicine, says it's a disturbing trend.
"Most of what we learn actually comes through our ears," said Dr. House.
The researchers analyzed data on 12- to 19-year-olds from a nationwide health survey. They compared hearing loss in nearly 3,000 kids tested from 1988-94 to nearly 1,800 kids tested over 2005-06.
The prevalence of hearing loss increased from about 15 percent to 19.5 percent.
Most of the hearing loss was "slight," defined as inability to hear at 16 to 24 decibels - or sounds such as a whisper or rustling leaves. A teenager with slight hearing loss might not be able to hear water dripping or his mother whispering "good night."
While Brooklyn's hearing loss may have be caused by excessive ear infections as an infant, many experts blame the popularity of MP3 players for the increase in high frequency hearing loss.
"Once this type of damage occurs, the nerve damage, it is permanent. And the answer if it gets bad enough is having to turn to hearing aids," said Dr. House.
Since Brooklyn got her hearing aids, her grades are getting better.
"I think that confidence has come back because she can hear what's going on around her," said Susan Miller.
A couple signs of hearing loss in a child are turning up the volume on the TV or not being able to hear you when you call them in a normal voice, said Dr. House. When in doubt, get them tested.
Dr. House suggests teens listening to loud music on MP3 players turn down the volume because high frequency hearing loss is cumulative.