An automotive vehicle soundproofing part having a body that includes a plurality of interlaced and/or bonded fibers. The body includes, in its thickness: a porous upper region of granular elements dispersed between the fibers; and a porous lower region with no dispersed granular elements, or formed of a concentration of dispersed granular elements lower than the concentration in dispersed granular elements of the porous upper region. The porous upper region has an air passage resistance at least 100 N·m−3·s greater than the air passage resistance of the porous lower region.