Low-density highly porous solid monolithic macroscopic objects, consisting of hierarchical mesoporous three-dimensional assemblies of nanoparticles (aerogels), have been previously pursued mainly for their low thermal conductivity. Unlike classical aerogels based on silica being fragile materials, structural fragility issue has been addressed with materials referred to as polymer-crosslinked (or X-) aerogels. X-aerogels are low-density materials, yet their mechanical strengths have been significantly increased. This work explores ductile aerogels in potential uses as constrained damping layers integrated into classical wallboards for drastically increased sound transmission losses without significantly increasing the board thickness and weight. Their ductility and mechanical strength enables light-weight X-aerogel panels of less than 1 cm in thickness to be integrated into gypsum wallboards. This work has experimentally investigated the integrated wallboards to achieve significantly increased sound transmission loss without significantly increasing thickness and weight of integrated wallboard system. This paper discusses preliminary investigations on experimental methods to characterize broadband dynamic properties of X-aerogels for better understanding of its excellent effect in drastically increased sound transmission loss. Some preliminary test results carried out in chamber-based random-incident measurements demonstrate high potentials in building acoustics applications and beyond.