C. Fritz, F. Coulouvrat, F. Marmel - Projet RUMBLE

The RegUlation and norM for low sonic Boom Levels (RUMBLE) European project aimed to quantify the effects of low sonic boom exposure on
human responses in representative situations for European citizens, so as to inform policy, establish standards and develop protection concepts
for a new generation of supersonic commercial aircraft that should emit a reduced but perceivable boom (a ”low boom”) while flying overland.

Noise and vibration dose to response relationships are needed to inform policy, establish standards and develop protection concepts in order to reduce the impact in communities and therewith decrease the overall annoyance of supersonic transportation noise. This objective must be
reached before a new generation of supersonic commercial aircraft, flying overland while emitting a reduced but perceivable boom, is developed. With this in view, a low boom simulator has been built as part of the project. One of the challenges was to simulate realistic sonic booms in an existing house, in order to satisfy as best as possible the requirement of ecological validity. The selected house is a two-storey accommodation house for students and invited professors located in Sorbonne University annex campus in Saint Cyr l’Ecole (France) in Paris metropolitan area. To reproduce the low frequency part (< 100 Hz) of the signal, which conveys most of the sonic boom energy, two wooden structures with six electromechanical subwoofers each have been assembled and installed outside the selected test house, just in front of the window frame of two ground floor rooms. The system is completed by two loudspeakers adapted to the higher frequencies of the sound signal. Various types of booms could be simulated, including N-waves, measured booms, low boom signals expected from numerical simulations of future aircraft concepts, and signals distorted by propagation in the atmosphere including influence of turbulence for more realism. The system allows the reproduction of booms in rooms directly or undirectly exposed, with or without rattle noise. An experiment was then conducted on about 40 participants to evaluate the impact of the simulated low booms on the performance (response time, accuracy, ...) of healthy adults in psychophysical and cognitive tasks, as well on the annoyance felt by the participants (collected via questionnaires) during the tasks and also during rest periods. The analysis of the numerous collected data will be presented, and the results along with recommendations for future work (in particular community surveys) will be discussed.