A head-mounted unit for assisting a user, such as a hearing-impaired user, is provided. The head-mounted unit comprises tracking sensors for monitoring a user wearing the head-mounted unit in order to determine a gaze direction which the user is looking. A sensor detects a sound source located in the identified gaze direction. Sound from the sound source may be recognised using speech recognition on captured audio from the sound source or computer vision on images of the sound source. A user interface provides information to the user to assist the user in recognising sound from the sound source.