Sound transmission loss of vacuum insulation panels

The sound transmission loss of a variety of vacuum insulation panels (VIP) has been measured in the laboratory. Core materials of the VIP include silica, polyurethane, micro fleece, and glass fibers. Mass law behavior and minima due to bending-wave coincidence and thickness resonance have been observed. Destroying the vacuum may reduce the sound insulation drastically. Since in practical applications the VIP need protection, the predominant interest lies in the transmission loss of multilayered assemblies, e.g., VIP sandwiched between aluminum plates. Calculations performed by the software LAYERS show that with additional “decoupling” layers (air, rubber) the coincidence dip can be avoided or shifted to higher frequencies, where it is less critical. Preliminary experimental realizations indicate the important role of a proper gluing of the layers. According to further LAYERS calculations, attachment of VIP to massive walls and protection by a plaster layer does not change the transmission loss of the wall appreciably, except for the VIP with the soft polyurethane core material.