Exploring the EarMetrics Concept: The Bony Ear Canal as a Non-Pigmented Site for Photoplethysmography

David Western, John Eveness, Beshoy Agayby, Xicai Alex Yue, Timothy Cox, Alistair Foster, Nick Gompertz

2025

Abstract

Photoplethysmography (PPG) is a well-established form of physiological sensing, but persistent challenges include skin-tone-dependent variations in performance and trade-offs between performance and acceptance factors in site selection. We propose that the inner, bony portion of the ear canal may offer several advantages over established sites, including reduced sensitivity to skin tone. We support this position through a combination of anatomical analysis, colorimetry, and the first examples of PPG data collected from the bony ear canal, including pulse oximetry calculations during voluntary breathholds. Colorimetry revealed no statistically significant differences in lightness, chroma, or hue of the bony canal between subjects with lighter versus darker external skin tones. The commonly used ratio-of-ratios (R) method for pulse oximetry was sensitive to de-oxygenation from breathholds, showing statistically significant correlation with breathhold duration. Our results show that the bony ear canal is not pigmented, and that PPG signals can be obtained from this site, even in the presence of idiosyncracies such as earwax and myringosclerosis.

Paper Citation

in Harvard Style

Western D., Eveness J., Agayby B., Yue X., Cox T., Foster A. and Gompertz N. (2025). Exploring the EarMetrics Concept: The Bony Ear Canal as a Non-Pigmented Site for Photoplethysmography. In Proceedings of the 18th International Joint Conference on Biomedical Engineering Systems and Technologies - Volume 2: WHC; ISBN 978-989-758-731-3, SciTePress, pages 1045-1052. DOI: 10.5220/0013401600003911

in Bibtex Style

@conference{whc25,
author={David Western and John Eveness and Beshoy Agayby and Xicai Yue and Timothy Cox and Alistair Foster and Nick Gompertz},
title={Exploring the EarMetrics Concept: The Bony Ear Canal as a Non-Pigmented Site for Photoplethysmography},
booktitle={Proceedings of the 18th International Joint Conference on Biomedical Engineering Systems and Technologies - Volume 2: WHC},
year={2025},
pages={1045-1052},
publisher={SciTePress},
organization={INSTICC},
doi={10.5220/0013401600003911},
isbn={978-989-758-731-3},
}

in EndNote Style

TY - CONF

JO - Proceedings of the 18th International Joint Conference on Biomedical Engineering Systems and Technologies - Volume 2: WHC
TI - Exploring the EarMetrics Concept: The Bony Ear Canal as a Non-Pigmented Site for Photoplethysmography
SN - 978-989-758-731-3
AU - Western D.
AU - Eveness J.
AU - Agayby B.
AU - Yue X.
AU - Cox T.
AU - Foster A.
AU - Gompertz N.
PY - 2025
SP - 1045
EP - 1052
DO - 10.5220/0013401600003911
PB - SciTePress