Sound barrier
BACKGROUND OF THE INVENTION 
     Various forms of sound barriers utilizing Helmholtz resonating chambers have been heretofore provided, but for various reasons these chambers have been mounted relative to each other in a manner to provide spacing slots therebetween extending through the barrier or the Helmholtz chambers have been mounted on backing panels in spaced parallel relationship relative to each other and with the backing panel including &#34;breathing slots&#34; formed therethrough in registry with the spacing between adjacent Helmholtz chambers. In the first instance, the slots are utilized to render the barrier at least somewhat visually transparent when the barrier is used along a roadway and, in the second instance, the breathing slots are provided to permit air circulation and to also render the barrier somewhat optically transparent. Examples of these two forms of Helmholtz chamber utilizing sound barriers are disclosed U.S. Pat. Nos.: 3,812,931 and 3,783,968. In addition, other sound barriers of somewhat similar construction are disclosed in U.S. Pat. Nos.: 3,630,310, 3,656,576, and 3,382,947. 
     It was previously believed that limited dimensional slots defined through a sound barrier utilizing Helmholtz chambers did not appreciably reduce the noise attenuation performance of the barrier and were desirable in order to provide a meaasure of visual transparency to the barrier and to minimize a reduction in noise attenuation performance of the barrier due to wind currents incident thereon. More recent studies indicate that the utilization of sound barrier structure provided with Helmholtz chambers and incorporating slots of the above-mentioned type results in appreciable reduction in noise attenuation performance of the barrier. 
     In addition, most sound barriers utilizing Helmholtz chambers must be reengineered in order to vary the resonance frequency of the barrier in order to adapt it for use in a particular noise abatement environment. Accordingly, a need exists for a sound barrier incorporating Helmholtz chambers and which does not include &#34;breathing slots&#34; or openings and which may be economically produced and &#34;tuned&#34; to a particular resonance frequency whereby the barrier may be specifically adapted for a particular noise abatement situation. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The sound barrier of the instant invention utilizes only four distinct components in addition to a backing panel upon which the four distinct components may be mounted. By slightly altering the dimensions and/or spacing between the four distinct components, the barrier may have its resonance frequency varied to suit a particular noise abatement situation. Still further, various materials may be utilized in the construction of the four distinct features of the barrier as well as the backing panel thereof and the barrier is, therefore, readily adaptable for use in numerous environments. 
     The main object of this invention is to provide an efficient noise attenuating barrier which is readily adaptable to construction in different sizes. 
     Another object of this invention is to provide a barrier in accordance with the preceding object and including distinct structural features thereof which may be readily manufactured at low cost and from various different materials. 
     Still another object of this invention is to provide a noise barrier whose construction enables the dimensional size of one or more of the distinct structural features thereof to be varied in order to vary the resonance frequency of the barrier. 
     Another important object of this invention is to provide a barrier which may be preformed and readily assembled and erected on the site of the desired sound barrier even by unskilleld workmen. 
     A further object of this invention is to provide a sound barrier which may be constructed from readily available renewable resource materials. 
     Yet another object of this invention is to provide a sound barrier which is of lightweight construction and is capable of being dismantled, transported and reused elsewhere without effecting its efficiency. 
     A final object of this invention to be specifically enumerated herein is to provide a sound barrier which will conform to conventional forms of manufacture, be of simple construction and easy to erect, so as to provide a device that will be economically feasible, long lasting and readily assembled. 
     These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a sound barrier section constructed in accordance with the present invention; 
     FIG. 2 is an enlarged, side, elevational view of the barrier section illustrated in FIG. 1 as seen from the right side of FIG. 1 and with portions of the barrier section broken away and illustrated in vertical section; 
     FIG. 3 is a fragmentary, enlarged, horizontal, sectional view taken substantially upon the plane indicated by the section line 3--3 of FIG. 1; 
     FIG. 4 is a fragmentary, enlarged, vertical, sectional view taken substantially upon the plane indicated by the section line 4--4 of FIG. 1; and 
     FIG. 5 is a fragmentary, perspective view of the upper portion of the barrier section illustrated in FIG. 1 with the Helmholtz chamber defining slats or panels removed. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now more specifically to the drawings, the numeral 10 generally designates a sound attenuating barrier section constructed in accordance with the present invention. The section 10 may vary vertical height and horizontal length, as desired, and includes a base panel 12 which is imperforate and is mounted from horizontal support members 14 extending between and anchored relative to supportive ground embedded posts 16. It is to be noted, however, that the base panel 12 may be supported in position as desired by other supportive structures. 
     In addition to the base panel 12, the section 10 includes a plurality of vertically spaced generally parallel mounting strips 18, 20 and 22 disposed over and secured to one side face of the panel 12 upon which sound to be attenuated may be directed. The strips 18, 20 and 22 comprise spacing strips as will be hereinafter more fully set forth. 
     Each of the strips 18, 20 and 22 has a plurality of generally horizontally outwardly projecting triangular mounting blocks 24 mounted thereon and spaced longitudinally therealong. The mounting blocks 24 supported from the strips 18, 20 and 22 are arranged in horizontally spaced sets of vertically aligned blocks 24 and each set of blocks 24 supports a pair of panels or strips 26 and 28 therefrom extending along, disposed in surface-to-surface contact with, and supported from corresponding side edges 30 and 32 of the blocks 24, the base edges of the blocks being supported from the strips 18, 20 and 22. The adjacent marginal edges of the strips 26 and 28 are overlapped as at 34 whereby the strips 26 and 28 define Helmholtz chambers 36 of substantially right triangular cross-sectional configuration opening toward the side of the panel 12 from which the strips 18, 20 and 22 are supported. The blocks 24 supported from the strip 20 serve to divide each of the Helmholtz chambers 36 into a pair of vertically spaced Helmholtz chamber sections. The space between adjacent pairs of strips 26 and 28 may be varied by varying the spacing between the sets of blocks 24 and also by changing the dimensions of the blocks 24 and correspondingly changing the width dimensions of the panels 26 and 28. Further, the areas between the panels 26 and 28 and the panel 12 define frequency slots 42 through which pressure waves incident upon the panel 12 between adjacent panel members 26 and 28 may enter the chambers 36. The width of the slots may be varied by using different thickness strips 18, 20 and 22 and the length of each of the chambers 36 may be varied by utilizing additional strips and blocks supported therefrom or additional strips independent of corresponding blocks 24 may be used. Thus, it may be seen that the resonance frequency of the chambers 36 may be varied when designing a barrier section 10 for a particular environmental usage in order that the barrier section 10 may be as effective as possible in noise attenuation performance. 
     Various materials may be utilized in forming the components 12, 18, 20, 22, 24, 26 and 28 in order to further tailor a given barrier section 10 to the particular environment in which it is to be used. 
     It is emphasized that the panel 12 is imperforate in order to eliminate any possibility of the barrier section 10 being acoustically transparent and that the width of the slots 42 as well as the openings 40 may be varied as desired in order to &#34;tune&#34; the barrier section 10 for use in a particular noise abatement environment. 
     The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.