An exemplary hearing device assembly is configured to be worn at least partially within an ear canal of a user. The hearing device assembly includes a housing including an output transducer configured to provide an output audio signal representative of sound presented to the user. The housing is configured to be positioned entirely within the ear canal. The hearing device assembly also includes a tube extending from an end of the housing and configured to provide an acoustic pathway from outside the ear canal to the housing, an inner seal extending from the housing, and an outer seal extending from the tube. The inner seal and the outer seal are together are configured to enclose a main volume that surrounds the tube within the ear canal and that is acoustically sealed from an ambient environment of the user.