  Body sounds provide rich information about the state of the human body and
can be useful in many medical applications. Auscultation, the practice of
listening to body sounds, has been used for centuries in respiratory and
cardiac medicine to diagnose or track disease progression. To date, however,
its use has been confined to clinical and highly controlled settings. Our work
addresses this limitation: we devise a chest-mounted wearable for continuous
monitoring of body sounds, that leverages data processing algorithms that run
on-device. We concentrate on the detection of heart sounds to perform heart
rate monitoring. To improve robustness to ambient noise and motion artefacts,
our device uses an algorithm that explicitly segments the collected audio into
the phases of the cardiac cycle. Our pilot study with 9 users demonstrates that
it is possible to obtain heart rate estimates that are competitive with
commercial heart rate monitors, with low enough power consumption for
continuous use.
