Uncertainty quantification of the diffuse sound field assumption in structure-borne sound radiation predictions
* Presenting author
When predicting the radiation of structure-borne sound into a room, it is often assumed that the generated sound field is diffuse. A diffuse field is by definition a random field: it represents a conceptual ensemble of rooms with the same volume and total absorption, but otherwise any possible arrangement of boundaries and small objects that scatter incoming sound waves. Adopting a diffuse sound field model therefore inherently introduces uncertainty on the computed results. This uncertainty can be important, especially at the lower frequency end of the spectrum. In this work, practical formulas are derived for predicting not only the mean, but also the variance of energetic level quantities, such as the band-integrated spatially averaged sound pressure level, in a diffuse sound field caused by a mechanically excited structure. The formulas are first validated in a simulation study, and then applied for predicting the sound pressure level in a room caused by impact excitation of plate structures. Both the average sound pressure level and its standard deviation can be well predicted. This information is essential e.g. for judging at which frequencies the mean diffuse field estimate is sufficiently accurate for the application at hand.