Technetics Group FELTMETAL™ Acoustic Media is an engineered, porous material made of sintered metal fibers.
Once an acoustic designer has located the dominant frequencies of untreated noise, the size of the fiber, porosity and thickness of the fibers are tuned to optimize noise absorption.
Within ducting applications, when a sound is reflected from a hard surface, constructive and destructive interference may occur, resulting in a series of sound waves. If a porous material is placed across the wave pattern, the movement of air molecules through the material is converted to heat, resulting in a reduction in sound intensity. The controlled porosity of acoustic media enables the gas to be expanded gradually, thereby reducing turbulence and the amount of noise generated. This reduction is highest if the FELTMETAL™ Acoustic Media is placed at a location where the air molecule velocity is a maximum ¼ of the sound wavelength. Finer fibers offer the advantage of lighter weight and lower non-linearity factors. To enhance the structural properties, the metal fibers may be reinforced by sintering to screen mesh or perforated plate.
FELTMETAL™ Acoustic Media is produced from Austenitic stainless steels (Types 316L and 347) and FeCrAIY fibers having diameters ranging from 50 to 150 microns.