Guideline "Implantable hearing aids"-short version : German S2k guideline of the Working Group of German-Speaking Audiologists, Neurootologists and Otologists (ADANO), of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery (DGHNO) in collaboration with the German Society of Audiology (DGA), the German Society of Phoniatrics and Pediatric Audiology (DGPP), and patient representatives