1. A vehicle including a passenger compartment, comprising: an arrangement for determining the position of the eyes of an occupant in a vehicle, said arrangement comprising: at least one wave-receiving transducer arranged to receive waves from the passenger compartment generated or modified by the occupant, and a processor coupled to said at least one transducer for analyzing the waves received by said at least one transducer and determining the location of the eyes of the occupant relative to the passenger compartment based on the analysis of the received waves.