An earpiece for a hearing device includes an ear canal part to be introduced into an ear canal of a user, the ear canal part comprising: an earpiece housing comprising a first end configured to be positioned medially inside the ear canal of the user, and a second end configured to be positioned laterally to the ear canal of the user, wherein the earpiece housing comprises a side wall between the first end and the second end； and a primary sensor, wherein the primary sensor is positioned inside a first volume in the earpiece housing； wherein the side wall of the earpiece housing comprises a first pass-through area, and wherein the primary sensor is configured to measure a physiological parameter through the first pass-through area.
