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 and a second side, the first side of the moldable fiber cap layer being uncovered, the moldable fiber cap layer further including an engineered fiber blend including one or more types of thermoplastic fibers, the moldable fiber cap layer having a first density;
• a moldable lofted sound absorber and vibration decoupling layer including a top side and a bottom side and being made from another engineered fiber blend including one or more types 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, the top side of the moldable lofted sound absorber and vibration decoupling layer being adhesively adhered to the 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 and a second side, the first side of the moldable fiber backer being adhesively 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 including one or more types 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 including a top side and a bottom side and being made from another engineered fiber blend including one or more types 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, the top side of the moldable lofted sound absorber and vibration decoupling layer being adhesively adhered to the 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.