I must admit to not having really paid attention to the intended energy needed to be mitigated or to the the actual design goals, so please bear with me as I am simply responding to methods that have proven to be useful for the support of non- or semi-rigid porous materials at similar orientations...
Assuming that one is not into designing a tuned rigid perforated absorbent membrane (which is actually not difficult!), an alternative material that provides superior support without overly imposing its own characteristics upon the task is to use common plastic orchard bird netting*. Not only is is relatively low cost (if you look a bit) and easy to work with in conjunction with any number of commonly available fasteners as well as fastening topologies.
Supported at reasonable intervals one can avoid sag while providing more than adequate support over and around even irregular surfaces, further augmented by its tensioning.
*Various perforated and expanded metals are also useful and effective, although at generally higher cost.