A hearing system includes a processing device, a hearing aid adapted to be worn by a user, and a data logger. The hearing aid includes an input transducer providing an electric input signal representing sound in the environment of the user, and a hearing aid processor executing a processing algorithm in dependence of a specific parameter setting. The data logger stores time segments of said electric input signal, and data representing a corresponding user intent. The processing device comprises a simulation model of the hearing aid. The simulation model is based on a learning algorithm configured to provide a specific parameter setting optimized to the user's needs in dependence of a hearing profile of the user, the logged data, and a cost function. A method of determining a parameter setting for a hearing aid is further disclosed.