Hearing devices configured to fit within the bony portion of the ear canal and batteries that may be used with same. One such hearing device includes a hearing device core, defining a size and a shape, and including a battery and an acoustic assembly, with a microphone and a receiver with a sound port that is adjacent to a portion of the battery, and a flexible seal apparatus on the hearing device core. The size, shape and configuration of the hearing device core, and the flexibility of the seal, are such that the hearing device is positionable within the ear canal bony region with the entire microphone medial of the bony-cartilaginous junction.