A high frequency attenuating device for an air flow induction system of a vehicle employing a thermoformed fibrous mat of any shape that fits robustly inside the duct. The dissipative nature of the fibrous mat helps in achieving broadband attenuation in the high frequency regime. The ability to manufacture the fibrous mat into any shape helps with restriction, targets different attenuation bands, and makes it more feasible to manufacture. Hybrid solutions are possible when combined with low frequency perforated silencers or high frequency QWT arrays injection molded onto them.

A high frequency attenuating device for an air flow induction system of a vehicle employing a thermoformed fibrous mat of any shape that fits robustly inside the duct. The dissipative nature of the fibrous mat helps in achieving broadband attenuation in the high frequency regime. The ability to manufacture the fibrous mat into any shape helps with restriction, targets different attenuation bands, and makes it more feasible to manufacture. Hybrid solutions are possible when combined with low frequency perforated silencers or high frequency QWT arrays injection molded onto them.

A flexible porous non-pollutive tube, wherein the walls of the tube are made by tapes formed by interlaced textile fibers, and to which activated charcoal is added, in agglomerate, powder or granulated form, and the textile tapes being wound over the charcoal and glued among the charcoal in the helical direction, forming an air conducting acoustic flexible helical pipe which is a part of a combustion engine's intake system used by the automobile industry, and adding the activated charcoal in the walls or in the pipe's external or internal lining.