| 摘要 |
Acoustical insulation for attenuating sound entering the passenger compartment of motor vehicles. The acoustical insulator comprises dual nonwoven layers in which one nonwoven layer is an airflow control layer and the second nonwoven layer is a support layer positioned between the cap layer and the sheet metal of the firewall separating the passenger and engine compartments. The areal density of the cap layer is less than the areal density of the support layer and, preferably, comprises polyethylene terephthalate (PET) fibers. The cap layer has a specific airflow resistance ranging from about 200 mks Rayls to about 1200 mks Rayls.
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