We present LubDubDecoder, a system that enables fine-grained monitoring of micro-cardiac vibrations associated with the opening and closing of heart valves across a range of hearables. Our system transforms the built-in speaker, the only transducer common to all hearables, into an acoustic sensor that captures the coarse "lub-dub" heart sounds, leverages their shared temporal and spectral structure to reconstruct the subtle seismocardiography (SCG) and gyrocardiography (GCG) waveforms, and extract the timing of key micro-cardiac events. In an IRB-approved feasibility study with 25 users, our system achieves correlations of 0.88-0.95 compared to chest-mounted reference measurements in within-user and cross-user evaluations, and generalizes to unseen hearables using a zero-effort adaptation scheme with a correlation of 0.91. Our system is robust across remounting sessions and music playback.
@article{arxiv.2509.10764,
title = {LubDubDecoder: Bringing Micro-Mechanical Cardiac Monitoring to Hearables},
author = {Siqi Zhang and Xiyuxing Zhang and Duc Vu and Tao Qiang and Clara Palacios and Jiangyifei Zhu and Yuntao Wang and Mayank Goel and Justin Chan},
journal= {arXiv preprint arXiv:2509.10764},
year = {2026}
}