Ear infections are typically diagnosed using specialized equipment to assess eardrum mobility. Researchers at the University of Washington have develop a smartphone app that help parents detect fluid buildup. With the help of a simple paper funnel, the app detects fluid buildup in a child's ear - one symptom of an ear infection. The app is still in it's experimental stage and would require clearance by the Food and Drug Administration before it could hit the market.   

This app works by sending sounds into the ear and measuring how those sound waves change as they bounce off the eardrum. The team's system involves a smartphone and a regular piece of paper that the doctor or parent can cut and fold into a funnel. The funnel rests on the outer ear and guides sound waves in and out of the ear canal. When the phone plays a continuous 150 millisecond sound -- which sounds like a bird chirping -- through the funnel, the sound waves bounce off the eardrum, travel back through the funnel and are picked up by the smartphone's microphone along with the original chirps. Depending on whether there's fluid inside, the reflected sound waves interfere with the original chirp sound waves differently.

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.

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 ears, such as a tonsillectomy.

Once diagnosed, ear infections can be easily treated with observation or antibiotics, and persistent fluid can be monitored or drained by a doctor to relieve symptoms of pain or hearing loss. A quick screening at home could help parents decide whether or not they need to take their child to the doctor.

The authors of the study published their results in the journal of Science Translational Medicine. The study suggest the app will be highly-accessible yet inexpensive test that could deliver immediate results. The goal is to make sure that the app is able to rival the accuracy that is provided by the results in the doctor's clinic.

"If this app can give accurate diagnosis similar to that of an ear specialist, it could really bring about a significant change in how ear infections are managed globally," said Justin Chang, one of the co-authors of the study. "It is a little bit similar to the tapping of a wine glass. The sound that you hear will depend on whether the glass is half empty or half full. The same principle can be applied to this type of testing through the app."

During the initial phase, children were used as test patients since they are more apt to developing ear infections. The app was able to correctly diagnose five children who all had ear infections. The experiments using the mobile app is still ongoing to ensure correct diagnosis.