Excerpt from "Sensing with Earables: A Systematic Literature Review and Taxonomy of Phenomena".

By adding sensing capabilities to ear-worn devices, earables have emerged as a new platform. The ears are located closely to a number of important anatomical structures (e.g., brain, blood vessels). Also, the ear canal deforms upon facial movements and the ears can be comfortably touched by the hands. In a recent paper, we conducted a systematic literature review of 271 earable papers. We synthesized an open-ended taxonomy of 47 phenomena that can be sensed in, on, or around the ear. We identified 13 fundamental phenomena from which all other phenomena can be derived, and discuss sensing principles to detect them. The phenomena were reviewed in-depth in four main areas: (i) physiological monitoring and health, (ii) movement and activity, (iii) interaction, and (iv) authentication and identification. This breadth highlights the potential earables have to offer as a ubiquitous, general-purpose platform.