With the soaring adoption of in-ear wearables, the research community has started investigating suitable in-ear Heart Rate (HR) detection systems. HR is a key physiological marker of cardiovascular health and physical fitness. Continuous and reliable HR monitoring with wearable devices has therefore gained increasing attention in recent years. Existing HR detection systems in wearables mainly rely on Photoplethysmography (PPG) sensors, however these are notorious for poor performance in the presence of human motion. In this work, leveraging the sound enhancing properties of the occlusion effect, which can be generated by sealing the entrance of the ear canal (something that some existing earphones already do to improve noise cancellation), we investigate for the first time \textit{in-ear audio-based motion-resilient} HR monitoring. This is done by measuring HR-induced sound in the human ear canal with in-ear microphones. Concretely, we develop a novel motion artefact (MA) removal technique based on wavelet transforms, followed by an HR estimation algorithm to extract HR from in-ear audio signals compounded with other activities (e.g., walking, running, and speaking). Unlike existing works, we present a systematic evaluation of our technique under a set of different motion artifacts and while speaking. With data collected from 15 subjects over four activities, we demonstrate that our approach achieves a mean absolute error (MAE) of 0.88$\pm$0.27 BPM, 8.11$\pm$3.89 BPM, 13.79$\pm$5.61 BPM and 7.49$\pm$3.23 BPM for stationary, walking, running and speaking, respectively, opening the door to a new non-invasive and affordable HR monitoring with usable performance for daily activities.
翻译:研究界开始调查适当的心脏内心率检测系统。HR是心血管健康和身体健康的关键生理标志。因此,近年来人们日益关注使用磨损装置进行持续和可靠的HR监测。在磨损装置中,现有的HR探测系统主要依靠光膜扫描仪(PPG)传感器,然而,这些系统臭名昭著,在人类运动面前的性能不佳。在这项工作中,利用封闭效应的声效增强值,可以通过封闭耳罐入口(一些现有的耳机已经为改进噪音取消而做了这种动作)产生。我们第一次调查的是带有磨损装置的Textit{在耳机上的音效监测系统。具体地说,我们开发了一种新型运动美化技术(MA),以可承受的速率转换为基础,然后用人力资源估算法算出$$(美元),用一些现有的耳机加速的音频信号(e.g.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h.h