In this paper, a headset with an ear-clip type, transmissive PPG (Photoplethysmography) sensor is presented which allows a continuous and realtime monitoring of the heart rate (HR) whilst listening to music during daily activities. Also, the proposed headset is equipped with a tri-axial accelerometer, which enables the measurement of calorie consumption and step counting. During a variety of daily activities (e.g., walking, jogging, and sleeping etc.), a PPG may be contaminated with motion artifacts. To remove these motion artifacts, we designed an adaptive filter based on the accelerometer.
To evaluate the accuracy of heart rate detection, for 13 subjects the HR from the headset was compared with that detected from the ECG simultaneously recorded with a conventional ECG recorder. As a result, the error rates of the headset are 0.6%, 1.7%, 0.7%, and 5.7% over rest, walking (3km/h), jogging (6 km/h), and running (9km/h), respectively.
From these results, it is likely that the proposed headset shows the performance good enough to be used in the continuous and real-time monitoring of the HR during daily activities. It is expected that the proposed headset is very efficient in the assessment of autonomic nervous activities under various physiological conditions, the exercise monitoring, and the evaluation of physical training performance.