Can You Ear Me?: A Comparison of Different Private and Public Notification Channels for the Earlobe

The earlobe is a well-known location for wearing jewelry, but might also be promising for electronic output, such as presenting notifications. This work elaborates the pros and cons of different notification channels for the earlobe. Notifications on the earlobe can be private (only noticeable by the wearer) as well as public (noticeable in the immediate vicinity in a given social situation). A user study with 18 participants showed that the reaction times for the private channels (Poke, Vibration, Private Sound, Electrotactile) were on average less than 1 s with an error rate (missed notifications) of less than 1 %. Thermal Warm and Cold took significantly longer and Cold was least reliable (26 % error rate). The participants preferred Electrotactile and Vibration. Among the public channels the recognition time did not differ significantly between Sound (738 ms) and LED (828 ms), but Display took much longer (3175 ms). At 22 % the error rate of Display was highest. The participants generally felt comfortable wearing notification devices on their earlobe. The results show that the earlobe indeed is a suitable location for wearable technology, if properly miniaturized, which is possible for Electrotactile and LED. We present application scenarios and discuss design considerations. A small field study in a fitness center demonstrates the suitability of the earlobe notification concept in a sports context.