In this paper, we study the spatialization of the sound field in rooms, in particular the evolution of the room impulse responses in function of their spatial positions. Thanks to this study, we are now able to predict the sound field in any position knowing the sound field in a certain number of positions in the room. If enough measurements are taken, we are able to completely characterize the sound field of the room at any arbitrary location. Further, we determine the number and the spacing between the microphones needed to reconstruct the sound field in a room up to a certain temporal frequency.