AUTHOR=Skoglund Martin A. , Balzi Giovanni , Jensen Emil Lindegaard , Bhuiyan Tanveer A. , Rotger-Griful Sergi 

TITLE=Activity Tracking Using Ear-Level Accelerometers

JOURNAL=Frontiers in Digital Health

VOLUME=Volume 3 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2021.724714

DOI=10.3389/fdgth.2021.724714

ISSN=2673-253X

ABSTRACT=Introduction: By means of adding more sensor technology, modern hearing aids (HAs) strive to become better, more personalized, and self-adaptive devices that can handle environmental changes and cope with day-to-day fitness of the users. The latest HA technology available in the market already combines sound analysis with motion activity classification based on accelerometers to adjust settings. While there is a lot of research in activity tracking using accelerometers in sports applications and consumer electronics, there is yet not much in hearing research. 

Objective: This study investigates the feasibility of activity tracking with ear-level accelerometers and how it compares to waist-mounted accelerometers, which is a more common measurement location.  

Method: The activity classification methods in this study are based on supervised learning. The experimental set-up consisted of 21 subjects, equipped with two XSens MTw Awinda at ear-level and one at waist-level, performing nine different activities.

Results: The highest accuracy on our experimental data were obtained with the combination of Bagging and Classification tree. The total accuracy over all activities and users was 84\% (ear-level), 90\% (waist-level), 91\% (ear-level + waist-level).  Most prominently the classes: standing, jogging, laying (on one side), laying (face-down), and walking all have an accuracy of above 90\%. Furthermore, estimated ear-level step-detection accuracy was 95\% in walking and 90\% in jogging.

Conclusions: It is demonstrated that several activities can be classified, using ear-level accelerometers, with an accuracy that is on par with waist-level.  It is indicated that step-detection accuracy is comparable to a high-performance wrist device. These findings are encouraging for development of activity applications in hearing healthcare.