Acoustic valve able to effect a selective and non-linear filtering of sounds

摘要

The valve, designed to give a selective and non-linear filtration of noise and fitted inside a perforated ear plug, consists of a tube (10) with two rigid transverse discs (12,12') set at a distance of 2-7 mm from one another. Each disc has at least one perforation (16), with the total perforated area of each disc is between 0.03 and 0.5 sq mm. The valve can be made from two hollow cylindrical sections (14,15), each closed by a disc with a central perforation (16) at one end and having a shoulder (151) at its other end to engage with the other section the two sections are made from a moulded rigid plastics material, e.g. 'Altuglas' (RTM) or an epoxy resin and each disc is 0.05 - 0.5 mm thick in the central perforated zone.