The application relates to a system comprising a portable electronic device and an auxiliary device, the portable electronic device and the auxiliary device each comprising an interface allowing the establishment of a communication link between them, at least to be able to transmit data representative of a status information from the auxiliary device to the portable electronic device. The application further relates to a method of of establishing a measure of an absolute elapsed time in a listening device. An object of the present application is to make available a system and a method wherein an improved absolute time estimate is provided in a portable electronic device. The problem is solved in that the portable electronic device comprises a timing unit for determining a time interval and a memory for storing data, and wherein the auxiliary device comprises a master timing unit for providing a signal representative of the present time, and wherein the system is adapted to transfer a signal representative of the present time from the auxiliary device to the portable electronic device and to store it in said memory. This has the advantage that an elapsed time, including a time where the portable electronic device has been turned off, can be estimated by the device itself. The invention may e.g. be used in devices that are turned on and off according to need, e.g. to conserve power, e.g. in listening devices such as hearing aids, headsets, ear phones, active ear protection systems, etc, in particular in applications where an algorithm needs an estimate of a real time elapsed, which is longer than a typical time of operation of the device in question.
