Process for Audible Acoustic Frequency Management in Gas Flow Systems

Abstract

A sound insulation process comprises (a) providing at least one sound barrier comprising a substantially periodic array of structures disposed in a first medium having a first density, the array comprising at least one row of at least two of the structures, the structures being made of a second medium having a second density that is greater than the first density, the second medium being a viscoelastic medium, an elastic medium, or a combination thereof, and the first medium being a gaseous medium; and (b) placing the at least one sound barrier in at least one at least partially enclosed gas stream in a manner such that the row of structures extends in a direction that is perpendicular to the direction of flow of the gas stream.

1 . A process comprising (a) providing at least one sound barrier comprising a substantially periodic array of structures disposed in a first medium having a first density, said array comprising at least one row of at least two said structures, said structures being made of a second medium having a second density that is greater than said first density, said second medium being a viscoelastic medium, an elastic medium, or a combination thereof, and said first medium being a gaseous medium; and (b) placing said at least one sound barrier in at least one at least partially enclosed gas stream in a manner such that said row of structures extends in a direction that is perpendicular to the direction of flow of said gas stream. 
     
     
         2 . The process of  claim 1 , wherein said array is a two-dimensional array, a three-dimensional array, or a combination thereof; and/or wherein said array has a fill factor in the range of 0.1 to 0.65. 
     
     
         3 . (canceled) 
     
     
         4 . The process of  claim 1 , wherein said gaseous medium is air. 
     
     
         5 . The process of  claim 1 , wherein said second medium is an elastic medium; a viscoelastic medium having a speed of propagation of longitudinal sound wave and a speed of propagation of transverse sound wave, the speed of propagation of longitudinal sound wave being at least about 30 times the speed of propagation of transverse sound wave; or a combination thereof. 
     
     
         6 . The process of  claim 1 , wherein said second medium is a viscoelastic medium. 
     
     
         7 . The process of  claim 6 , wherein said viscoelastic medium has a speed of propagation of longitudinal sound wave that is at least 30 times its speed of propagation of transverse sound wave at least in the audible range of acoustic frequencies; and/or wherein said viscoelastic medium is selected from viscoelastic solids, viscoelastic liquids, and combinations thereof. 
     
     
         8 . (canceled) 
     
     
         9 . The process of  claim 7 , wherein said viscoelastic solids and viscoelastic liquids have a steady shear plateau modulus of less than or equal to 5×10 6  Pa at 20° C. 
     
     
         10 . (canceled) 
     
     
         11 . The process of  claim 7 , wherein said viscoelastic solids and said viscoelastic liquids are selected from rubbery polymer compositions and combinations thereof. 
     
     
         12 . The process of  claim 11 , wherein said rubbery polymer compositions are selected from elastomers, elastoviscous liquids, and combinations thereof. 
     
     
         13 . The process of  claim 1 , wherein said second medium is an elastic medium. 
     
     
         14 . The process of  claim 1 , wherein said elastic medium has a speed of propagation of longitudinal sound wave that is at least 2000 meters per second. 
     
     
         15 . The process of  claim 13 , wherein said elastic medium is an elastic solid selected from metals, metal alloys, inorganic minerals, glassy polymers, and combinations thereof. 
     
     
         16 . The process of  claim 1 , wherein said structures have a configuration selected from spheres, circular cylinders, at least partially hollow circular cylinders, and combinations thereof. 
     
     
         17 . The process of  claim 1 , wherein said structures are hollow. 
     
     
         18 . The process of  claim 1 , wherein said structures have exposed surfaces that comprise a material other than a foam or fibrous material. 
     
     
         19 . The process of  claim 1 , wherein said at least partially enclosed gas stream is in a gas flow duct. 
     
     
         20 . The process of  claim 1 , wherein said process provides a transmission loss that is greater than or equal to 20 dB across the range of 800 Hz to 10,000 Hz. 
     
     
         21 . The process of  claim 1 , wherein said sound barrier further comprises at least one local resonance structure. 
     
     
         22 . A process comprising (a) providing at least one sound barrier comprising a substantially periodic, two-dimensional or three-dimensional array of solid or at least partially hollow cylindrical structures in a square lattice pattern surrounded by a gas matrix having a first density, said array comprising at least one row of at least two said structures, said structures being made of a second medium having a second density that is greater than said first density, said second medium being a viscoelastic medium, an elastic medium, or a combination thereof and (b) placing said at least one sound barrier in at least one gas stream in at least one gas flow duct in a manner such that said row of structures extends in a direction that is perpendicular to the direction of flow of said gas stream. 
     
     
         23 . The process of  claim 22 , wherein said array is a two-dimensional array, said cylindrical structures are circular cylindrical structures, said circular cylindrical structures have exposed surfaces that comprise a material other than a foam or fibrous material, and said gas flow duct is part of an HVAC system in a building, an HVAC system in a transportation vehicle, a face mask for gas delivery, a fan-containing consumer appliance, or a combination thereof. 
     
     
         24 . (canceled) 
     
     
         25 . (canceled)