Abstract: The invention comprises a hearing aid, which has a casing containing a signal receiving part for receiving an audio signal, an audio transducer for providing an audio signal to the user, a signal transmission path between the signal receiving part and the audio transducer, whereby a battery is provided for powering the signal receiving part, the signal path and the audio transducer, and where further means are provided for assessing the function of the hearing aid and for generating an electrical indication signal which indicates the function of the hearing aid and where further means are provided for intermittently generating a power signal in response to the electrical indication signal and where means are provided for converting the power signal into a light signal, such that the light signal is visible from outside the hearing aid.