around an hvac device the innermost epp layer 102 absorbs acoustic energy emanating from the hvac device the mass loaded vinyl layer 104 serves as a mass dampening sound transmission reduction layer the low density porous epp layer 106 is operative to absorb remaining low frequency acoustic energy the thicknesses masses and densities of the layers 102 104 106 can be adjusted for optimal noise reduction in the air handling broadband and condensing low frequency sections as set forth below in equation 1 an empirical diffuse field equation sets forth the relationship between sound reduction i e sound transmission loss and thickness and density of the sound barrier tl transmission loss db u03c1b barrier density h barrier thickness u03c9 2 pi frequency u03c1c acoustic impedance of air referring to fig2 the exemplary configuration 100 may be used as an acoustic enclosure 120 that surrounds or partially surrounds a motor or other potential sound emitting device in such a circumstance the enclosure 120 may include an internal skeleton or frame 122 that is mounted to the exemplary configuration 100 to impart greater rigidity and support to the enclosure in particular the innermost epp layer 102 is molded to include channels 126 that receive portions of the frame 122 in order to mount the frame to the innermost epp layer referencing fig3 and 4 the exemplary acoustic enclosure 120 includes a sheet metal outer skin 110 in order to attach the outer skin 110 to the respective layers 102 104 106 the outer skin includes a series of cutouts 128 that define deflectable tabs 130 in exemplary form the tabs are deflected inward toward the location where the respective layers 102 104 106 will be located prior to the layers being received.