Middle ear disorders are one of the most common causes of preventable hearing loss. Unfortunately, while the developing world bears a disproportionate burden of these disorders, it often lacks access to diagnostic tools.

Tympanometry is a key test to measure middle ear function, but remains available only on expensive test equipment that costs $2000-$5000. In countries like Kenya where hearing screening programs are less developed, hospitals often have to rely on a very small number of tympanometers donated by non-profit foundations like Hear the World. However, these hospitals still remain strained on resources, and have to serve patients who travel from as far as a nine-hour drive away for hearing screenings.

Another problem faced by medical humanitarian groups like Doctors without Borders is that they often only have access to bulky, desktop-bound tympanometers which are inconvenient to transport. Furthermore, these devices require a wall outlet for power, and are not designed to work in the event of electrical failures which occur with greater frequency in developing countries.

We present a low-cost smartphone-based tympanometry system. The device is able to change the air pressure of the ear canal and measure ear drum mobility. Our system, for which the software and hardware are openly available, is tested in 50 ears from children attending an audiology clinic. A panel of pediatric audiologists classified tympanometry measurements from our device and a commercial tympanometer with good agreement. Given the increasing availability of smartphones in developing countries, our system has the potential to make screening of middle ear disorders more accessible.

Check out the project page: https://tymp.cs.washington.edu/