SOUND ABSORBING PANEL AND SYSTEM

Abstract

Disclosed are a sound absorbing panels and a sound absorbing system using such panels, particularly for use in reducing highway and railway noise. The panel includes an enclosure including a first panel face with a number of apertures or holes to allow sound passage, where the ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage. The enclosure is configured such that an inner surface of the first panel face is proximate to a fibrous sound absorbing material with an area approximately equal to the total area of the first panel face. The panel enclosure may have various shapes and configurations for optimal sound absorption, and may be configured in a sound absorbing system such that one or more of the panels are mountable to existing structures, such as sound barrier walls in a retrofit manner.

Description

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present Application for Patent claims priority to Provisional Application No. 61/458,485 entitled “Sound Absorbing Barrier for Highways and Railroads” filed Nov. 24, 2010, and hereby expressly incorporated by reference herein.

BACKGROUND

Field

The present disclosure relates generally to sound absorbing panels, and more specifically to a sound absorbing panel for use in applications such as reducing vehicle noise from roads and railways.

Background

It is known that roadways and railways, for example, are sources of significant noise approximately 85 decibels and upward. In order to mitigate this noise, particularly in the case of roads and railways close to residential areas, a known solution is provide sound barrier walls between the noise source and an area desired to have lowered noise levels. Sound barrier walls operate primarily on the principle of noise reflection, wherein a portion of the noise energy from a noise source is reflected back toward the source or at least away from the desired noise reduced area. A problem with such walls, however, is that noise or sound energy has both a magnitude or amplitude (e.g., sound pressure in decibels), as well as a direction. Thus, a certain amount of noise either projects directly over the barrier, some noise is diffracted at the top of the barrier back down toward the area on the other side of the barrier, and still further, some of the noise is transmitted through the barrier wall itself.

These problems are illustrated by FIG. 1, wherein some of the noise from noise source 102, such as a vehicle on a roadway, is reflected away by barrier 103 from an area 104 where noise reduction is desired as shown by vector 105. However, particular noise from source 102 having a direction of travel upward will pass over barrier 103 as indicated by vectors 108. Additionally, portions of this noise are diffracted from the top of barrier 103 downward to the area 104, thus increasing ambient noise levels. This noise can approach 70 dBA or greater. Finally, since the noise barrier 103 is sound reflecting with poor sound absorption properties, a portion of the noise from noise source 102 will be transmitted through the barrier 103 as illustrated by vector 112.

There is therefore a need in the art for better mechanism for sound absorption, and, in particular, for a sound absorption mechanism that is capable of being placed by roadways and other similar noise sources for improved noise reduction.

SUMMARY

According to a first aspect, a sound absorbing panel is disclosed having an enclosure including a first panel face including a plurality of apertures or holes that allow for the passage of sound energy. The ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage, with the first panel face having a first side comprising an outer surface of the enclosure and a second side comprising an inner surface of the enclosure. The panel further includes a fibrous sound absorbing material having a first side with an area approximately equal to the total area of the first panel face and the first side of the sound absorbing material disposed proximate to the second side of the first panel face.

In another aspect, a sound absorbing panel system is disclosed that includes one or more sound absorbing panels configured to be mounted to a surface positioned to receive incident noise from one or more noise sources. Each of the one of more sound absorbing panels has an enclosure including a first panel face including a plurality of apertures or holes that allow for the passage of sound energy. The ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage, with the first panel face having a first side comprising an outer surface of the enclosure and a second side comprising an inner surface of the enclosure. The panel further includes a fibrous sound absorbing material having a first side with an area approximately equal to the total area of the first panel face and the first side of the sound absorbing material disposed proximate to the second side of the first panel face.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of how noise travels in a system using reflective noise barriers;

FIG. 2 is an exploded trimetric view of an exemplary sound absorbing panel;

FIG. 3 is a side sectional view of the assembled sound absorbing panel of FIG. 2;

FIG. 4 is an trimetric view of another exemplary sound absorbing panel having an angled portion;

FIG. 5 is an trimetric view of yet another exemplary sound absorbing panel having an curved portion;

FIG. 6 is a trimetric view of a sound barrier wall including a sound absorption system comprising a plurality of the presently disclosed sound absorbing panels mounted on the barrier wall.

DETAILED DESCRIPTION

The present invention provides a sound absorbing panel and system that provides exceptional sound absorbing/noise reduction performance that previously has not been achieved with sound absorbing panels, such as panels for reducing road noise. In particular, the presently disclosed panels combine a fibrous textile material with sound absorbing properties with a particular face having a specific aperture to area of sound absorbing ratio. This arrangement may be put together in a housing that allows for positioning and easy attachment of the sound absorbing apparatus to existing wall structures, such as sound barrier walls 103. Furthermore, the panels may be configured with different face topologies to better meet directional noise and mitigate diffraction over sound bathers.

FIG. 2 is an exploded trimetric view of an exemplary sound absorbing panel according to the present disclosure. The panel 200 may be configured as an enclosure including a first portion or panel face 202 including a plurality of apertures 204 that allow sound energy to pass to sound absorbing material 206. Additionally, the enclosure may include a second portion or backing portion 208 for enclosing the material 206 when assembled and meeting with the first panel face 202.

Sound absorbing material 206 is composed of a textile fibrous sound absorbing material. As one example, the material 206 may have a composition including thick cotton textile material, such as denim In a particular aspect, the material 206 may comprise bonded, high performance recycled cotton fiber material manufactured by Bonded Logic, Inc. of Chandler, Ariz.

In an embodiment, the material 206 may be monolithic and rectangular in shape as illustrated in FIG. 2, but is not limited to a single piece of material or a rectangular shape, and could be configured in any number of various shapes (with the enclosure 208 and face 202 matching the shape of the material). In another aspect, the thickness 210 of material 206 is 2 inches or greater to provide optimal sound absorption, but the thickness may be less if desired or if size constraints exist. Additionally, the construction of material 206 is configured to afford a degree of rigidity and tensile strength such the material 206 may be manipulated to accommodate different topologies of the panel face 202 (as will be discussed later), while still maintaining shape and rigidity (i.e., termed herein as “semi-rigid”) such that if the larger planar surface of panel 200 is placed vertically (i.e., the plane of first panel face 202 is vertical), for example, material 210 will not sag but remain durable and in place substantially occupying the volume of the enclosure (i.e., the enclosure defined by the combination of face 202 and portion 208).

FIG. 3 shows a side sectional view of the assembled sound absorbing panel of FIG. 2. As may be seen in this embodiment, material 206 fills the back of the enclosure 208 and has a surface 214 with area equal or at least approximately equal to the area of the first panel face 202. This surface 214 is disposed proximate to or abutting an inner face 216 of the panel face 202. All of the apertures 204 in panel face are thus occluded by the material 202 on the inside face 216 to ensure that sound passing through each aperture impinges on the material 206.

It further noted that having surface 214 may have an area approximately equal to the total area of the first panel face (i.e., 212), and the ratio of the area of the apertures 204 to the total area of the first panel face 212 is set at a predetermined percentage or ratio. In an aspect, a ratio of approximately 0.23 (or 23%) has been found to provide an optimal ratio for providing maximum sound absorption. It is noted, however, that this ratio is not intended to be limiting, and that other ratios could be used in the presently disclosed panels. Additionally, although the apertures 204 are illustrated as round or circular, apertures 204 could be configured in other shapes such as ovals or various polygonal shapes, as merely two examples. Furthermore, the pattern of the plurality of apertures 204 may be arranged such that the centers of the apertures are spaced equidistant or at regular intervals, but is not necessarily limited to regular patterns.

The materials used for constructing the first panel face 202 and the enclosure portion 208 may be any suitable material(s) known in the art. For example, face 202 and portion 208 may be constructed of one or more a plastic, such as polymers (e.g., polyethylene) or copolymers (e.g., ABS), metals such as aluminum or steel, composites, fiberglass, wood, etc.

Although panel 200 is illustrated herein in a rectangular configuration, one skilled in the art will appreciate that the shape of the panel is not so limited and could be configured in various polygonal shapes, conic sectional shapes, or in random or stylized shapes. Furthermore, the example of FIGS. 2 and 3 illustrate a substantially planar panel, but it is noted that angled or curved configurations are contemplated as will be discussed below.

FIG. 4 is an trimetric view of another exemplary sound absorbing panel 400 having an angled portion and employing the principles, materials, and aperture configuration of the panel in the example of FIGS. 2 and 3. As illustrated, panel 400 may include a first portion 402 lying substantially in a plane illustrated by line 403. A second portion 404 is angled at angle a 406 with respect to plane 403 and, therefore, portion 402. It is contemplated that with this angled construction, if the panel were located at the top of noise barrier wall (e.g., 103 in FIG. 1), the angle portion 404 may be better oriented to meet incident noise (e.g., noise 108 shown in FIG. 1) at incident angles that provide optimal performance for a particular application of the panel.

Panel 400 includes the sound absorbing material 206, which having a semi-rigid property may be angled within the panel 400. In an alternate embodiment, two or more separate pieces of the material 206 may be used, such as one piece for portion 402 and another piece for portion 404. In still another alternative, it is contemplated that the junction of portion 402 and 404 may be joined in a hinged manner (not shown) allowing the angle a to be varied and set to an angle that achieves optimal sound absorption for a particular installation.

FIG. 5 is trimetric view of yet another exemplary sound absorbing panel 500 having an curved construction and employing the principles, materials, and aperture configuration of the panel in the example of FIGS. 2 and 3. Similar to angled panel 400, panel 500 may include a planar portion 502 and another portion 504 that is configured in a curved manner. The particular radius of the curve may set to any of a number of values, and also need not be a constant radius, but could either an accelerating or decelerating radius as desired. The curved configuration is contemplated to allow sound absorption over a wider angle, and affords a variable surface (i.e., the curve has a changing perpendicular point (i.e., a gradient) by its nature) that can more effectively absorb variously angled sound waves impinging thereupon. In an alternative, it is contemplated that panel 500 could be constructed without planar portion 502, and simply be an entire It is noted that both panels 400 and 500 may be particularly useful when mounted high on a wall structure, such as barrier 103, although it is also contemplated that they may be useful mounted lower on a wall as well.

FIG. 6 is a trimetric view of a sound absorption system including the presently disclosed sound absorption panels with a sound barrier wall (or other structure). In the exemplary system 600 of FIG. 6, a structure 602, such as a highway or railway sound barrier wall, may incorporate a system of one or more various sound absorbing panels 604, 606, 608. The system 600 incorporates one or more of the presently disclosed sound absorbing panels being configured to be mountable to structure 602 (or any vertical, angled, or horizontal surface to which unwanted noise is incident). As illustrated in this example, flat panels 604, curved panels 606, or angled panels 608 (or any combination thereof) may be employed. In an aspect, the curved or angled panels 606, 608 may be beneficial when placed near the top of structure 602 as shown to better absorb noise that would otherwise pass over a barrier and be diffracted downward. In addition to shape, the number or density of the panels can be tailored to a location, such as to minimize the cost but meeting required sound absorbent levels, or alternatively the panels may be installed as a dense array of a plurality of panels with small or no gaps therebetween. The panels can be used in new installations or retrofitted to existing structures. With respect to retrofitting, in particular, it is noted that there are over 2000 miles of existing sound reflective barriers used on highways in the United States. Thus, the present system is particularly beneficial in providing a means to add actual sound absorption as a retrofit to existing structures, thus saving cost by not having to erect new structures for thousands of miles of highway to implement the system.

Although the presently disclosed sound absorbing panels have been described in the context of highway and railway noise absorption, the present panels could be used in any environment where unwanted noise impinges on a space such as around construction sites, airports, or even inside buildings.

Of final note, an embodiment of the disclosed sound absorbing panel was tested at the Riverbank Acoustical Laboratories (RAL)™ using Reverberation Room Method ASTM C 423-07NVLAP 08/P03. The tested panel having approximately 23% of the face of the panel comprising apertures received a test result of 0.95 Noise Reduction Coefficient (NRC). This coefficient effectively means that 95% of the sound impinging on the panel was be absorbed, which is a result not known to Applicant to have been achieved by such type of sound absorbing panels previously. Thus, the novel combination of the fibrous textile material and a panel face having a specific ratio of aperture area to total surface area has been shown to provide exceptional sound absorbing properties.

The present description of the disclosed examples is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sound absorbing panel comprising:

an enclosure including a first panel face including a plurality of apertures, wherein the ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage, the first panel face having a first side comprising an outer surface of the enclosure and a second side comprising an inner surface of the enclosure;

a fibrous sound absorbing material having a first side with an area approximately equal to the total area of the first panel face and the first side of the sound absorbing material disposed proximate to the second side of the first panel face.

2. The panel as defined in claim 1, wherein the predetermined percentage is 23%.

3. The panel as defined in claim 1, wherein each of the plurality of apertures are round.

4. The panel as defined in claim 1, wherein the first face is planar.

5. The panel as defined in claim 1, wherein a first portion of the first face lies in a plane and a second portion of the first face is angled away from the plane.

6. The panel as defined in claim 1, wherein a first portion lies in a plane and a second portions curves and extends away from the plane.

7. The panel as defined in claim 1, wherein the fibrous sound absorbing material comprises at least cotton denim fibers.

8. The panel as defined in claim 1, wherein the fibrous sound absorbing material is semi-rigid and monolithic.

9. The panel as defined in claim material has thickness of at least approximately 2 inches.

11. A sound absorbing panel system comprising:

one or more sound absorbing panels configured to be mounted to a surface positioned to receive incident noise from one or more noise sources, each of the one of more sound absorbing panels comprising: an enclosure including a first panel face including a plurality of apertures, wherein the ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage, the first panel face having a first side comprising an outer surface of the enclosure and a second side comprising an inner surface of the enclosure; and a fibrous sound absorbing material having a first side with an area approximately equal to the total area of the first panel face and the first side of the sound absorbing material disposed proximate to the second side of the first panel face.

12. The system as defined in claim 11, wherein the predetermined percentage is 23%.

13. The system as defined in claim 11, wherein a first portion of the first face lies in a plane and a second portion of the first face is angled away from the plane.

14. The system as defined in claim 11, wherein a first portion lies in a plane and a second portions curves and extends away from the plane.

15. The system as defined in claim 11, wherein the fibrous sound absorbing material comprises at least cotton denim fibers.

16. The system as defined in claim 11, wherein the fibrous sound absorbing material is semi-rigid and monolithic.

17. The system as defined in claim 11 wherein the fibrous sound absorbing material has thickness of at least approximately 2 inches.

18. The system as defined in claim 11, wherein the surface comprises at least one of a highway sound reflecting barrier wall and a railroad sound reflecting barrier wall.

19. The system as defined in claim 18, wherein the surface is part of existing structures and the system is further configured to be mountable to the surface as a retrofit system.