The symptoms of ear infections can be a little vague, and can be easily confused with other conditions. To help clear up such diagnoses, researchers from the University of Washington have come up with a “user-friendly” mobile app that can quickly detect the presence of fluid behind the eardrum using just a cone of paper and a phone. Researchers say that the new system, which was tested on 98 young patients in a pediatric surgical center, could provide a “low-cost and effective” tool for parents to detect ear infections such as acute otitis media, a leading cause of visits to doctors.

Researchers say that detecting middle ear fluid is a “critical” need in pediatric medicine – but existing tests, such as tympanometry, either can’t be performed at home or require expensive equipment. To overcome such hurdles, scientists at the University of Washington School of Medicine created a system that uses a commercial smartphone’s existing speakers and microphones to send audible “chirps” of sound into the ear canal, via a simple homemade paper cone, so it can analyze the reflected acoustic signals and predict middle ear status. A deeper pitch in the sound indicates that the middle ear is filled with fluid. When no fluid is present, the eardrum vibrates and sends a variety of sound waves back.

According to the National Institute on Deafness and Other Communication Disorders, ear infections are among the most common reasons for a visit to the family doctor with a child. For parents and carers, a device which enables them to tell quickly, unobtrusively and with confidence if a child’s distress is likely due to an ear infection or not, could not only be a time-saver, but a big relief.