The invention relates to an at least partially implantable hearing system comprising a microphone assembly (26) for capturing audio signals from ambient sound an audio signal processing unit (32) for processing the audio signals captured by the microphone assembly an implantable main electromechanical output transducer (46) for direct mechanical stimulation of the cochlea (24) according to the audio signals processed by the audio signal processing unit an implantable box (20) having a central part (66) and an open flange (68) for penetrating through the cochlear wall (22) into the perilymph fluid (70), wherein the inner cross section of the central part is larger than the inner cross section of the flange and wherein the electromechanical output transducer is for acting on the perilymph fluid in the central part of the box through a port provided at the box. The box comprises at least one of a port (82) for an implantable auxiliary electromechanical output transducer (48) for acting on the perilymph fluid in the central part of the box, a port (94) for drug application into the perilymph fluid in the central part of the box, a port (94) for taking out perilymph fluid from the central part of the box, a port (84) for applying optical stimuli to the perilymph fluid of the cochlea, and a port (86) for at least one sensor (88) for sensing at least physical or chemical parameter of the perilymph fluid in the central part of the box.Linvention concerne un système auditif au moins partiellement implantable comprenant un ensemble microphone (26) destiné à capturer des signaux audio à partir dun son ambiant, une unité de traitement de signaux audio (32) destinée à traiter les signaux audio capturés par lensemble microphone, un transducteur de sortie électromécanique principal (46) implantable permettant une stimulation mécanique de la cochlée (24) en fonction des signaux audio traités par lunité de traitement de signaux audio, et un boîtier implantable (20) comportant une pa
