A system for real-time enhancement of an audio/speech signal on a network derives hearing capability parameters of a user at predetermined frequencies (via a hearing test 67) and using this unique hearing profile (which may be linked to a user MSISDN reference number) to eg. filter or adjust the audio signal. A second users voice may be characterised by a unique voice profile in order to shift the pitch or tone of the speech towards the hearing profiles requirements, and ambient noise filtered before delivery to the users device. This pre-enhancement may take place centrally within eg. a mobile phone network (20, fig. 2) so as to simulate a user-end hearing aid.
