Bone Anchored Hearing Aids (BAHA). The bone anchored hearing aid or BAHA is a small vibrator that can be reversibly plugged onto a titanium screw that is implanted behind the ear. It transduces sound into vibration of the screw and stimulates the cochleae by means of the bone conduction pathway. The main indications are conductive hearing loss or mixed hearing loss with a moderate perceptive component when classical hearing aids cannot be worn, and rehabilitation of unilateral deafness. The indications, contra-indications, surgical technique and results are discussed in this paper.