초록 ▼

A cellular material, preferably a low density foam material, having an initial average normal incidence sound absorption coefficient for a selected frequency range is perforated to form a perforated cellular sound absorption material. The perforated cellular sound absorption material formed has an a

A cellular material, preferably a low density foam material, having an initial average normal incidence sound absorption coefficient for a selected frequency range is perforated to form a perforated cellular sound absorption material. The perforated cellular sound absorption material formed has an average normal incidence sound absorption coefficient for the selected frequency range greater than the initial average normal incidence sound absorption coefficient of the cellular sound absorption material. The depth(s), diameter(s), shape(s) and pattern of the perforations provide the cellular sound absorption material with the improved sound absorption properties that are reflected in the increased average normal incidence sound absorption coefficient of the material.

대표청구항 ▼

[ What is claimed is:] [1.] A perforated cellular sound absorption material comprising:a perforated cellular foam material; the perforations having an average diameter no greater than about 0.25 inches; the perforated cellular material having a density of less than about 2.0 pounds/ft.sup.3 ; the pe

[ What is claimed is:] [1.] A perforated cellular sound absorption material comprising:a perforated cellular foam material; the perforations having an average diameter no greater than about 0.25 inches; the perforated cellular material having a density of less than about 2.0 pounds/ft.sup.3 ; the perforated cellular material having an average normal incidence sound absorption coefficient for a selected frequency range between 0 Hertz and 10,000 Hertz greater than an initial average normal incidence sound absorption coefficient of the cellular material for the selected frequency range prior to the formation of the perforations in the cellular material; andthe cellular material having an initial baseline airflow resistance in excess of 5000 Rayls prior to the formation of the perforations; and the perforated cellular material having an airflow resistance less than the initial baseline airflow resistance of the cellular material prior to the formation of the perforations.