Sound field measurements inside a reverberant room by means of a new 3D method and comparison with FEM model

A newly developed low cost 3D positioning system is used to measure the sound field inside a reverberant room. The measurement is performed moving a microphone inside the reverberant room (excited with a multi-tone signal or with an MLS signal) and measuring, point by point, the local sound pressure level and the impulse response, in order to perform a modal analysis and compute a spatially localized reverberation time. The results of the measurements are compared with a FEM model of the reverberation room. The measurement system requires a normal computer, a standard multi-channel sound card and very few inexpensive external components such as 4 small amplified loudspeakers (used for the 3D positioning system) placed at known fixed positions and a microphone, used as probe for both the positioning and the sound field measurements. A dodecahedron is used to excite the reverberant room. The 3D measurement system is described in details.