Abstract: An acoustical door comprising an inner core assembly includes a spacer frame having a first set of spacer strips extending along a first direction and a second set of spacer strips extending along a second direction. The inner core assembly further includes first and second core layers positioned within the spacer frame. The second core layer is constructed of a material dissimilar from the first core layer. The acoustical door further comprises a multi-layer skin spaced apart from the inner core assembly. The multi-layer skin includes a sheet constructed of lead. The acoustical door also includes a spacer coupling the multi-layer skin and the inner core assembly around a mutual periphery. An air space is defined within the mutual periphery and between the multi-layer skin and the inner core assembly such that the multi-layer skin is configured to flex independent of the inner core assembly.