An enclosure having at least one wall, the wall includes an inner panel comprising, in sequence outwardly from the enclosure hollow interior, an inner sheet comprising a plurality of perforations extending therethrough, a plurality of panel stiffening members coupled to the inner sheet, and at least one inner panel sound absorption member comprising non-metallic sound absorption material positioned between adjacent of the plurality of panel stiffening members, and an outer panel comprising in sequence inwardly from outside of the enclosure, an outer panel sandwich member comprising non-metallic composite material including spaced-apart first and second walls and a plurality of spaced-apart transverse walls extending between the first and second walls defining hollow chambers therebetween, the outer panel coupled to the inner panel such that an outer surface of the inner panel is substantially flush against an outer surface of the outer panel.