Mass-deployable Smartphone-based Objective Hearing Screening with Otoacoustic Emissions

Since hearing loss is one of the most widespread disabilities and can often be addressed by early detection and intervention, there is a strong interest in technologies for cost-effective and mass-deployable hearing screening. Towards this, smartphones have been used for subjective tests where a sequence of tones are played to a subject who has to appropriately respond upon hearing them. But such tests are inappropriate where, e.g., children are involved who cannot provide reliable feedback, or the test takes too long. In this paper, we investigate an alternative modality to develop an objective screening test using smartphones. It relies on how the cochlea actively distorts tones emitted into the ear. By measuring these distorted signals, it is possible to reliably deduce the subject's hearing health. But smartphones are not designed to detect such low signals, and the suitability of a phone depends on the signal processing characteristics of the phone's hardware. In this paper we investigate this issue in detail and conclude that some smartphones are suitable for objective screening tests that require no interaction with a subject. This opens up new screening options that were not available before and have immense societal implications in developing countries.