Perforated hard trim for sound absorption
A perforated hard trim construction for incorporation into a an automobile interior with sound absorbing properties is provided. In one variation, the perforated hard trim construction includes a non-perforated metal component and a perforated hard trim component having a plurality of openings and connected to the non-perforated metal component. The plurality of openings have a sufficient total area such that the random incidence absorption coefficient is greater than about 0.1 for one-third octave center frequencies from about 1000 to about 10000 Hz. In an important variation, an porous sound absorbing material is interposed between the non-perforated hard trim component and the perforated hard trim component.
1 . A perforated hard trim construction for absorbing sound in an automobile interior, the perforated hard trim construction comprising:
a non-perforated metal component;
a perforated hard trim component having a plurality of openings and connected to the non-perforated metal component, wherein the plurality of openings have a sufficient total area such that the random incidence absorption coefficient is greater than about 0.1 for one-third octave center frequencies from about 1000 to about 10000 Hz;
a exterior absorbing material disposed over the perforated hard trim component; and
a fabric layer covering the first absorbing layer.
2 . The perforated hard trim construction of claim 1 wherein the plurality of openings have a total surface area less than about 12% of the surface area of the perforated hard trim component wherein a average opening area in the plurality of openings is less than about 30 mm 2 .
3 . The perforated hard trim construction of claim 1 wherein the plurality of openings have a total surface area from about 5% to about 10% of the surface area of the perforated hard trim component.
4 . The perforated hard trim construction of claim 3 wherein the average opening area in the plurality of openings is from about 0.10 to about 20 mm 2 .
5 . The perforated hard trim construction of claim 3 wherein the average opening area in the plurality of openings is from about 0.15 to about 10 mm 2 .
6 . The perforated hard trim construction of claim 1 wherein the plurality of openings have a sufficient total area such that the random incidence absorption coefficient is greater than about 0.2 for one-third octave center frequencies from about 2000 to about 10000 Hz.
7 . The perforated hard trim construction of claim 1 further comprising an interior porous material interposed between the non-perforated metal component and the perforated hard trim component.
8 . The perforated hard trim construction of claim 7 wherein the porous material has a density from about 10 kg/m 3 to about 50 kg/m 3 .
9 . The perforated hard trim construction of claim 8 wherein the porous material has a density from about 20 kg/m 3 to about 30 kg/m 3 .
10 . The perforated hard trim construction of claim 1 wherein the plurality of openings are a plurality of substantially circular holes.
11 . A automobile interior perforated hard trim construction comprising:
a non-perforated metal component;
a perforated hard trim component having a plurality of openings and connected to the non-perforated metal component, the plurality of openings having a total surface area less than about 12% of a surface area of the non-perforated metal component wherein the average area of an opening in the plurality of openings is less than about 30 mm 2 ; and
a porous material interposed between the non-perforated metal component and the perforated hard trim component; wherein the interior perforated hard trim construction has a random incidence absorption coefficient is greater than about 0.2 for one-third octave center frequencies from about 1000 to about 10000 Hz.
12 . The perforated hard trim construction of claim 11 wherein the plurality of openings have a total surface area from about 5% to about 10% of the surface area of the perforated hard trim component.
13 . The perforated hard trim construction of claim 12 wherein the average opening area in the plurality of openings is from about 0.10 to about 20 mm 2 .
14 . The perforated hard trim construction of claim 12 wherein the average opening area in the plurality of openings is from about 0.15 to about 10 mm 2 .
15 . The perforated hard trim construction of claim 11 wherein the porous material has a density from about 10 kg/m 3 to about 50 kg/m 3 .
16 . The perforated hard trim construction of claim 1 wherein the plurality of openings are a plurality of substantially circular holes.
17 . The perforated hard trim construction of claim 11 further comprising:
an exterior absorbing material disposed over the perforated hard trim component; and
a fabric layer covering the first absorbing layer.
18 . A automobile interior perforated hard trim construction comprising:
a non-perforated metal component;
a perforated hard trim component having a plurality of openings and connected to the non-perforated metal component, the plurality of openings having a total surface area less than about 12% of a surface area of the non-perforated metal component wherein the average area of an opening in the plurality of openings is less than about 30 mm 2 ;
an interior porous material interposed between the non-perforated metal component and the perforated hard trim component;
an exterior absorbing material disposed over the perforated hard trim component; and
a fabric layer covering the first absorbing layer, wherein the interior perforated hard trim construction has a random incidence absorption coefficient is greater than about 0.2 for one-third octave center frequencies from about 1000 to about 10000 Hz.
19 . The perforated hard trim construction of claim 18 wherein the average opening area in the plurality of openings is from about 0.10 to about 20 mm 2 .
20 . The perforated hard trim construction of claim 19 wherein the average opening area in the plurality of openings is from about 0.15 to about 10 mm 2 .