Device for controlling the porosity of a helical, flexible, sound-absorbing air-conducting tube

Abstract

Device for controlling the porosity of a helical, flexible, sound-absorbing, air-conducting tube; the present patent relates to a device comprised of a variable-width, non-porous film strip (2) helically arranged in a discontinued manner between the external layer or lining (1), formed of a helical strip of porous material (1-A) and the inner, cylindrical layer or lining (3), formed of a helical strip of porous material (3A0 of a flexible, cylindrical tube, the film strip (2) being intended to control the porous strips (5) of the tube wall and determining, by reason of the width of said film strip (2), a non porous strip (4) on the tube wall, with a consequent control of the acoustic attenuation.

Dependencies are inferred from the claim text.