A triaxial accelerometer-based approach for motion noise resilient segmentation of seismocardiogram signal

Seismocardiography (SCG) utilises an accelerometer to monitor the heart's vibrations. The accelerometer's compact size and light weight make it suitable for wearable heart monitoring. However, motion artefacts from walking or subject movement contaminate the signal in both the time and frequency domains, making monitoring challenging. Monitoring during activity provides deeper insight into cardiovascular function as blood flow demands increase. Existing denoising methods often suppress heart sounds along with high-amplitude motion noise. In contrast, this paper introduces a novel approach to classify and eliminate noise components without affecting the heart sounds, thereby enhancing segmentation accuracy. A triaxial accelerometer is strategically positioned on the chest to capture SCG (z-axis) and motion noise from walking (x-axis). An adaptive Yen's threshold method is developed to detect peaks in the SCG signal. Machine learning models are then trained using time- and frequency-domain features to classify these components, enabling the removal of noise peaks from the SCG signal. Clustering-based post-processing further improves the segmentation. The decision tree model achieves 99% accuracy in identifying Fundamental Heart Sounds (FHSs) in healthy subjects. These findings suggest that, with further clinical validation across diverse patient populations, the proposed approach could revolutionize home monitoring, offering a more accurate and insightful analysis of cardiac activity during daily activities.