May 17, 2019
Ear infections send more children to the pediatrician than any other ailment, according to the National Institutes of Health.
Even the youngest child may pull or tug at his or her ear when pressure and pain start to build up inside. This condition, usually caused by a bacterial infection, occurs when fluid gets trapped in the middle ear behind the eardrum. The same type of problem also is common in another condition called otitis media with effusion—where the infection is gone, but the fluid has not drained.
Any kind of fluid buildup in the ears can hurt and make it hard for children to hear, which is especially detrimental when they are learning to talk.
But now, researchers at the University of Washington have created a new smartphone app that can detect fluid behind the eardrum, when used along with three easily available aids: a piece of paper and the smartphone’s microphone and speaker.
The smartphone makes a series of soft audible chirps into the ear through a small paper funnel and—depending on the way the chirps rebound to the phone—the app determines the likelihood of fluid present with a probability of detection of 85% (similar to the results achieved with more sophisticated processes used currently, including acoustics and puffs of air).
When there is no fluid behind the eardrum, the eardrum vibrates and sends a variety of sound waves back. These sound waves mildly interfere with the original chirp, creating a broad, shallow dip in the overall signal. But when the eardrum has fluid behind it, it doesn’t vibrate as well and reflects the original sound waves back. They interfere more strongly with the original chirp and create a narrow, deep dip in the signal.
“Designing an accurate screening tool on something as ubiquitous as a smartphone can be game-changing for parents as well as healthcare providers in resource-limited regions,” said co-author Shyam Gollakota, an associate professor in the UW’s Paul G. Allen School of Computer Science & Engineering. “A key advantage of our technology is that it does not require any additional hardware other than a piece of paper and a software app running on the smartphone.”
A quick screening at home could help parents decide whether or not they need to take their child to the doctor.
“It’s like tapping a wine glass,” said co-first author Justin Chan, a doctoral student at the Allen School. “Depending on how much liquid is in [the ear], you get different sounds. Using machine learning on these sounds, we can detect the presence of liquid.”
To train an algorithm that detects changes in the signal and classifies ears as having fluid or not, the team tested 53 children between the ages of 18 months and 17 years at Seattle Children’s Hospital. About half of the children were scheduled to undergo surgery for ear tube placement, a common surgery for patients with chronic or recurrent incidents of ear fluid. The other half were scheduled to undergo a different surgery unrelated to their ears, such as a tonsillectomy.
Among the children getting their ear tubes placed, surgery revealed that 24 ears had fluid behind the eardrum, while 24 ears did not. For children scheduled for other surgeries, two ears had bulging eardrums characteristic of an ear infection, while the other 48 ears were fine. The algorithm correctly identified the likelihood of fluid 85% of the time, which is comparable to current methods that specialized doctors use to diagnose fluid in the middle ear.
Then the team tested the algorithm on 15 ears belonging to younger children between 9 and 18 months of age. It correctly classified all five ears that were positive for fluid—as well as nine out of the ten ears, or 90%, that did not have fluid.
“Even though our algorithm was trained on older kids, it still works well for this age group,” said co-author Dr. Randall Bly, an assistant professor of otolaryngology at the UW School of Medicine who practices at Seattle Children’s Hospital. “This is critical because this group has a high incidence of ear infections.”
Because the researchers want parents to be able to use this technology at home, the team trained parents how to use the system on their own children. Parents and doctors folded paper funnels, tested 25 ears and compared the results. Both parents and doctors successfully detected the six fluid-filled ears. Parents and doctors also agreed on 18 out of the 19 ears with no fluid. In addition, the sound wave curves generated by both parent and doctor tests looked similar.
Rajalakshmi Nandakumar, a doctoral student in the Allen School, is also a co-author on this paper. This research was funded by the National Science Foundation, the National Institutes of Health and the Seattle Children’s Sie-Hatsukami Research Endowment.
The team published its results on May 15 in the journal, Science Translational Medicine.
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