US3819010A

US3819010A - Sound-absorbing wedge

Info

Publication number: US3819010A
Application number: US00302653A
Authority: US
Inventors: G Adams; W Meisenbach
Original assignee: Armstrong Cork Co
Current assignee: Armstrong World Industries Inc
Priority date: 1972-11-01
Filing date: 1972-11-01
Publication date: 1974-06-25
Anticipated expiration: 1991-06-25

Abstract

A wedge-shape sound-absorbing structure is positioned and hung from a conventional ceiling system. The wedge functions as the sound-absorbing structure to limit noise exposure in industrial areas. The wedge is formed of boards which have a sound-absorbing characteristic.

Description

United States Patent [191 Adams et 31.

SOUND-ABSORBING WEDGE Inventors: George R. Adams, Lancaster;

William T. Meisenbach, Columbia, both of Pa.

Armstrong Cork Company, Lancaster, Pa.

Filed: Nov. 1, 1972 Appl. No.: 302,653

Assignee:

US. Cl. 181/33 GD, 181/33 G, 181/33 GE, 52/144, 52/145 Int. Cl E04g 1/99, GlOk 11/04 Field of Search 181/33 G, 33 GE, 33 GD; 52/144-145 References Cited UNlTED STATES PATENTS Bedell et a1. 181/33 GD Peterson 181/33 G [45] June 25, 1974 2,840,179 6/1958 Junger 181/33 G 2,886,859 5/1959 3,321,877 5/1967 2,753,44O 7/1956 Warefield 181/33 GD FOREIGN PATENTS OR APPLICATIONS 1,279,145 11/1961 France 181/33 GD 1,111,836 3/1956 France 181/33 GD 1,111,836 6/1958 France 181/33 GD Primary Examiner-Richard B. Wilkinson Assistant Examiner-Vit W. Miska [5 7] ABSTRACT A wedge-shape sound-absorbing structure is positioned and hung from a conventional ceiling system. The wedge functions as the sound-absorbing structure to limit noise exposure in industrial areas. The wedge is formed of boards which have a sound-absorbing characteristic.

3 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION Maximum Allowable dBA Level Hours of Exposure A certain percentage of the workers will still experience work-associated hearing losses at these exposure ranges, but they have been established as a realistic initial goal. It is believed that by 1980, the maximum 8- hour exposure level may be lowered from the present 90 dBA to somewhere between 85 and 88 dBA.

The decibel, when used as a unit of sound measurement, is a logarithmic function of the sound intensity. A reduction of 3 decibels corresponds to a halving of the sound intensity.

The dBA scale of measurement responds to noises much as does the human ear; that is, it emphasizes the importance of the middle frequencies required for good communication and reduces the significance of the lower frequencies. The Occupational Safety and Health Act requirements are referenced to the A Scale of measurement. The following are some examples of various common noises.

Noise Source Decibels Jet aircraft at take-off l40-l50 Threshold of pain 140 Loud power mower 107 Food blender 90-95 Stenographic work in a large office 80 Range of conversation 60-70 Quiet residence at night 40 Whisper 2O Threshold of hearing (youth) 3. Acoustical treatment of surfaces to reduce the amount of reflected noise.

4. Operator treatment which involves the use of ear plugs and ear muffs.

The first three above methods are preferred since the wearing of ear plugs could possibly cause operator discomfort and would require enforcement by the employer. The application herein is directed to the third control technique.

Acoustical ceilings are old in the art and the art has also used baffles and screens on ceilings for additional sound-absorbent purposes. U.S. Pat. No. 2,884,512 shows something similar to a wedge structure which is used. as part of an overall ceiling system. However, the

structure in the above mentioned patent is built into the overall ceiling system and is tied in with the lighting system and the fire protection system of a room.

SUMMARY OF THE INVENTION The invention herein is a wedge-shaped sound absorber made from acoustical panels or boards. A frame structure is made to form a triangular wedge-shaped structure. Into the frame is placed acoustical boards. The sound absorber is designed so that it can be installed on an existing lay-in ceiling or it may be installed directly to any ceiling. The angled shape and open back provides an attractive sound absorber and its irregular shape helps dissipate noise. The open back allows the insertion within the wedge of additional acoustical material. It can be readily installed in position and any number can be installed in close proximity to noisy machinery.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a view of the invention herein mounted in position.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawing herein, the soundabsorbing wedge 2 is designed to be mounted to an existing ceiling system. This could be a ceiling system which already contains acoustical panels or it could simply be the structural ceiling of any room.

The sound-absorbing wedge 2 is formed from a framework of approximately 1 inch metal corner molding, which is nothing more than thin pieces of metal bent in the middle with a angle between the sides. A number of these pieces of corner molding are put together to form two triangular end members for the sound wedge and an interconnecting bottom member which connects the peaks of the two triangular end members. The structure is mounted in position with the peak of the end members facing downwardly. This metal framework 6 serves to hold acoustical boards 8 in position. The acoustical boards are conventional perforated surface acoustical boards such as is wellknown in the art in most conventional ceiling systems. The boards are simply fiberboard structures which are provided with perforations in the surface thereof to assist the board to act as a sound absorber. The acoustical boards are placed in the framework 6 along the two sides and ends of the metal framework. This forms a wedge-shaped structure which has the point of the wedge facing downwardly away from the ceiling structure 4.

There is a cavity within the wedge. As shown in the exposed portion of the FIGURE, within this cavity, there are placed bags 12 of sound-absorbing material. The bags of sound-absorbing material would be thin I- mil-thick plastic bags which are filled with a mineral wool, fiberglass or inorganic aggregate. In particular, the bags have been prepared from l-mil polyethylene plastic material and been filled with 500 grams of mineral wool each. A number of these bags would then be placed in the open cavity in the backside of the soundabsorbing wedge 2. These bags greatly increase the sound-absorbing ability of the sound-absorbing wedge 2. It is obvious that batts, boards or other means may be used in lieu of bags to provide additional acoustical material.

The invention herein has been used specifically in a printing press room. In an area of 1,250 square feet of ceiling surface over the press structures, there were placed a total of 174 wedge-shaped sound absorbers which constitute about 1,000 square feet of acoustical board. These were suspended 3 inches from a conventional acoustical board ceiling system and were spaced about 1 foot apart. As shown in the drawing, any conventional hanging structure could be used to hold the wedge 2 in place relative to the ceiling. Through the use of the above wedges on the ceiling, it was possible to secure a reduction of 3 dBA in the sound level of the room. This was sufficient to all areas of the press area to meet the requirements of the Occupational Safety and Health Act as proposed for 1980. While the number of decibels may appear to be a small change, it must be remembered that 3 decibels correspond to a halving of the sound intensity. Relieving of the sound intensity secured a very favorable reaction from the workers involved with the presses.

What is claimed is:

1. In a room which is subjected to a high decibel noise level and where there is a closed room structure with a ceiling therein, the improvement comprising the placing of a number of independent, unconnected sound-absorbing wedges suspended from the ceiling, said sound-absorbing wedges comprising a support means into which is placed a plurality of soundabsorbing boards to form a wedge-shaped structure which is triangular in cross section, said support means being formed of two triangular end members and one connecting member joining together the lower corner of each triangular end member, said sound-absorbing boards being at least two boards which extend between both triangular end members to form the wedge shape for the sound-absorbing wedges, and each wedge has a board structure positioned in each triangular end member and each said board therein is exposed to open area outside of said support structure, said wedges being suspended from the ceiling system with the pointed end of the wedge facing towards the area below the ceiling, whereby the sound-absorbing wedges increase the sound-absorbing ability of the overlying ceiling system.

2. The sound wedge of claim 1 wherein the back side of the wedge adjacent the ceiling is open and into which is placed sound-absorbing material in bags formed of one-mil thick plastic material.

3. The sound wedge of claim 1 wherein the wedges are independently suspended from the overlying ceiling system and are spaced apart approximately one foot in distance so that they function as supplemental soundabsorbing surfaces for the purpose of increasing the sound-absorbing ability of the overlying ceiling system.

Claims

1. In a room which is subjected to a high decibel noise level and where there is a closed room structure with a ceiling therein, the improvement comprising the placing of a number of independent, unconnected sound-absorbing wedges suspended from the ceiling, said sound-absorbing wedges comprising a support means into which is placed a plurality of sound-absorbing boards to form a wedge-shaped structure which is triangular in cross section, said support means being formed of two triangular end members and one connecting member joining together the lower corner of each triangular end member, said sound-absorbing boards being at least two boards which extend between both triangular end members to form the wedge shape for the sound-absorbing wedges, and each wedge has a board structure positioned in each triangular end member and each said board therein is exposed to open area outside of said support structure, said wedges being suspended from the ceiling system with the pointed end of the wedge facing towards the area below the ceiling, whereby the sound-absorbing wedges increase the sound-absorbing ability of the overlying ceiling system.

3. The sound wedge of claim 1 wherein the wedges are independently suspended from the overlying ceiling system and are spaced apart approximately one foot in distance so that they function as supplemental sound-absorbing surfaces for the purpose of increasing the sound-absorbing ability of the overlying ceiling system.