Sound absorbing/sound blocking products, including trim products formed
from a porous fibrous layer backed by a sound absorbing layer and a sound
blocking layer for use within vehicles, and methods of making same, are
provided. A porous fibrous layer structure including a fibrous layer
backing is heated to achieve a fluid or semi-fluid state and then
subjected to vacuum to draw air through the fibrous layer backing to
create a porous structure. A layer of sound absorbing and a layer of
sound blocking material may be applied to the porous fibrous layer
backing to provide improved acoustic properties. An underlayment may
further be included to provide selected areas of increased thickness and
provide tailoring of sound attenuation.