This paper is the second of two companion papers. In the first paper, entitled "The acoustic response of rooms with open windows to airborne sounds", expressions for the acoustic field generated inside a room with an open window due to incoming transient or periodic signals have been presented. In this paper the technique has been applied to the specific example of an N-wave type signal. Detailed mathematical analysis is followed by its approximate version and numerical computation. Results of controlled experiments, using simulated sonic booms, have been compared with theoretical predictions. This has been followed by a general discussion about the build-up of acoustic fields inside rooms.