Noise attenuator element in ventilation duct - has absorbent blocks with dimensions and axial spacing selected relative to noise frequency

摘要

The rod-shaped noise attenuator element (1) is intended for arrangement in axial direction in a ventilation duct or the like with a distance between itself and the duct walls. It comprises a carrier of perforated sheet material (4) with streamlined entry baffle (6), containing blocks (2) in an absorbent material whose length in axial duct direction equals one eighth to one wavelength of the frequency to be attenuated. The blocks are axially spaced at a distance of between one sixth to half this wavelength. The blocks may have a square cross-section. The spaces (3) may contain two axially extending splitter partitions at right angles to one another, or parallel splitter partitions spaced at a quarter wavelength from the outer surface.