A subset of wearables are the so-called hearables – in-ear devices that are well suited for long-term monitoring as they are non-invasive, inconspicuous and easy to fasten. Hearables offer two major benefits: their proximity to the torso and vascular system of the brain and ear is a physiological advantage and motion artefacts often seen with wrist wearables are no longer an issue for in-ear devices.

https://healthcare-in-europe.com/en/news/from-the-wrist-into-the-ear-the-potential-of-hearables.html