By Liz White, UT staffAuburn Hills, Michigan-Dow Automotive says it has developed a new dashmat construction-called ABA-that enables engineers to block transfer of noise through the firewall, while absorbing interior noise behind the instrument panel. And it is based on barrier materials, with polyurethane foam forming the sound absorption layer, because of its good characteristics in this use. "Until now, a tightly sealed barrier was the best way to block engine noise," said Dan Pezolt, Dow Automotive's business development manager. "The ABA construction also enables us to reduce the weight and cost of the barrier-only systems while maintaining the ability to seal the passenger cabin and consolidate parts."The ABA (absorber-barrier-absorber) dashmats are commercially available.Dow says the injection-moulded dash insulator helps prevent engine and drive-train noise from entering the passenger compartment. Additional moulded-in options-footrests, electrical wiring channels, fasteners, cowl sides, cowl tops, and sealing features-can reduce system cost by eliminating the need for separate components. The PU foam absorbers can offer additional acoustical benefits by tuned via selection of specific materials. According to Dow, the two substrates can be bonded together or fastened mechanically. "