Vibro-acoustic Response of Panels Excited by a Diffuse Acoustic Field: Experimental Estimation of Sensitivity Functions using a Reciprocity Principle

The experimental characterization of the vibroacoustic response of panels excited by a Diffuse Acoustic Field (DAF) is of great interest, especially for building acoustics and industrial applications. Theoretically, a DAF is usually defined as an infinite number of uncorrelated plane waves with uniformly distributed incidence angles. However, completely diffuse conditions can hardly be reached in practice, and important variabilities are also seen between sound insulation tests performed in different laboratories. To circumvent these issues, a methodology is developed for experimentally characterizing a panel response to a DAF excitation, defined by its theoretical model. Indeed, the formulation of the problem in the wavenumber domain allows estimating the system response at a given M point from the DAF cross-spectral density function and so-called "sensitivity functions". These functions characterize the panel vibroacoustic response to parietal plane waves and can be experimentally determined using a reciprocity principle, which states that they are equal to the panel velocity field expressed in the wavenumber domain when the system is excited by a point source at a point M. For validation purposes, the proposed technique is applied numerically and experimentally on a simply supported rectangular plate. The interests and possible applications of this approach are finally discussed.