A bone anchored hearing aid (BAHA) is a surgically implanted auditory prosthetic based on bone conduction. It is an option for patients without external ear canals, when conventional hearing aids with a mold in the ear cannot be used. The BAHA uses the skull as a pathway for sound to travel to the inner ear. For people with conductive hearing loss, the BAHA bypasses the external auditory canal and middle ear, stimulating the functioning cochlea. For people with unilateral hearing loss, the BAHA uses the skull to conduct the sound from the deaf side to the side with the functioning cochlea.