Sound attenuating device using an embedded layer for acoustical tuning

A layered acoustical system for sound attenuation in a vehicle comprising:

• a moldable fiber cap layer including a first side of the moldable fiber cap layer being uncovered, the moldable fiber cap layer further including an engineered fiber blend of thermoplastic fibers, the moldable fiber cap layer having a first density;
• a moldable lofted sound absorber and vibration decoupling layer made from another engineered fiber blend of thermoplastic fibers, the moldable lofted sound absorber and vibration decoupling layer having a second density that is less than the first density of the moldable fiber cap layer, a top side of the moldable lofted sound absorber and vibration decoupling layer being adhered to a second side of the moldable fiber cap layer;
• and
• an intermediate layer embedded in and adhered to a location within a single layer of the layered acoustical system to achieve a balance point between transmission loss and sound absorption.

A layered acoustical system for sound attenuation in a vehicle comprising:

• an external decorative layer;
• a moldable fiber backer including a first side of the moldable fiber backer being adhered to a back side of the external, non-tufted and un-backed decorative layer, the moldable fiber backer further including an engineered fiber blend of thermoplastic fibers, the moldable fiber backer having a thickness of about 3 mm and a density of about 807 gsm;
• a moldable lofted sound absorber and vibration decoupling layer being made from another engineered fiber blend of thermoplastic fibers, the moldable lofted sound absorber and vibration decoupling layer having a thickness in the range of from 3 to 30 mm and a density of about 1610 gsm, a top side of the moldable lofted sound absorber and vibration decoupling layer being adhered to a second side of the moldable fiber backer;
• and
• a perforated film layer including a heat activated adhesive on opposite sides of the perforated film layer, the perforated layer having a thickness of about 0.5 mm, a plurality of perforations each having a diameter of about 380μ and a hole density of about 30 holes/in2, and an airflow resistance of approximately 900 Rayls, the perforated layer being embedded in and adhered to a location within the moldable lofted sound absorber and vibration decoupling layer to achieve a balance point between transmission loss and sound absorption.