Effects of variations in the tragus expansion angle on physical comfort for in-ear wearables

Abstract

Tragus expansion angle (TEA) is an angular variable that quantifies the outward degree of expansion of the tragus cartilage induced by in-ear wearables (designed with hard materials) fitted into the external ear. It is a physical factor that directly influence user's comfort experience during interaction with in-ear wearables. This study was aimed at quantifying the effects of variations in TEA on physical comfort. TEA was measured and normalised employing a measuring device and Tragus Expansion Index (TEI) proposed in this study. Physical (dis)comfort was assessed using a rating scale designed based on the 5-point Likert and Borg-CR10 scales. Comparatively, the comfort range of variations in TEA was similar for both genders. Males could endure a higher level of variations in TEA compared to females. A quantitative relationship between variations in TEA and (dis)comfort ratings was established using TEI values and GaussAmp function, which can be employed for ergonomic design purposes.

Practitioner summary: This study provides an empirical and available source for quantifying the effects of variations in the tragus expansion angle on physical comfort, including quantitative tools and (dis)comfort rating models, which could be used as a reference for improving the fit, comfort and functional capacity of in-ear wearable devices.

Keywords:

• In-ear wearables
• physical comfort
• tragus expansion angle
• quantitative analysis
• ergonomic design

Acknowledgements

We express our thanks to the participating individuals for their time and effort. We thank Mr. Z. Fan (ICBC Xuzhou Branch) for his support in sampling.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study is partly supported by the Special Project of National Civil Aircraft (Grant No. MJ-2015-F-018), National Key R&D Program (Grant Nos. 2019YFB1405701 and 2019YFB1405702). Additional support comes from Fesher Aviation Components (Zhenjiang) Co., Ltd., and the University of California Berkeley/San Francisco Ergonomics Research Program.