Abstract:
A protective material for acoustic transmission is disclosed which optimizes sound transmission of the material while also providing a barrier from ambient conditions to transducers. The protective material of the disclosure is a self-tensioning membrane with properties such that sound attenuation is minimized as the membrane transfers acoustic energy. In one embodiment, the self-tensioning membrane is used to cover an opening in an electronic device enclosure by securing the entire outer edge of the membrane with an adhesive. Such a construction creates an unbound region where the self-tensioning membrane can effectively transmit sound energy by moving in response to incoming sound waves. The self-tensioning membrane allows sound to travel out of the protective enclosure while also preventing liquid or particulate intrusion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/725,013 filed on Nov. 11, 2012 and entitled “PROTECTIVE MATERIAL FOR ACOUSTIC TRANSMISSION”, the subject matter of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to protective materials suitable for use in acoustic transmission applications. The present invention is further directed to casings and/or protective enclosures suitable for housing a sound-producing device (e.g., a speaker). 
     BACKGROUND 
     Protective materials for acoustic transmission described in prior art typically focus on membrane porosity as a means of sound transmission and are designed for portable electronics where they provide a barrier from liquid intrusion to sufficiently small acoustic transducers and acoustic vent openings (e.g., less than 5 cm 2 ), as commonly found in cellphones and other portable electronic devices with transducers. Other electronics, such as portable speaker systems, require a similar level of protection as demanded for cellphones, but acoustic vent openings in portable speaker enclosures are required to be significantly larger than that of a cellphone or small portable electronic device. Furthermore, some modern portable speaker systems can emit sound with frequency in the range of 20 Hz-20 kHz. The prior art does not adequately teach the materials or construction required to optimize sound transmission and protection for large acoustic vent openings nor does it effectively address the need for optimizing acoustic transmission across a broad range of audible frequencies. 
     There is a need in the art to provide improved protective materials for acoustic transmission, wherein the protective materials provide exceptional acoustic transmission across a broad range of audible frequencies, for example, in the range of 20 Hz to 20 kHz. 
     SUMMARY 
     The present invention addresses some of the difficulties and problems discussed above by the discovery of a protective material for acoustic transmission. 
     A protective material for acoustic transmission is disclosed that serves as a barrier from liquid and particulate intrusion to sound emitting devices while providing better sound transmission properties than prior art sound-transmissive protective materials. The disclosed protective material is a polymeric membrane that exhibits excellent sound transmission and resistance to long-term liquid entry due to the ability of the membrane to create and maintain tension as well as other physical properties including mass and thickness. The focus on membrane self-tensioning properties allows for the construction of a sound transmissive cover that effectively reduces sound transmission loss and sound contamination observed in sound transmissive covers and membranes defined in prior art. 
     According to one embodiment of the disclosure, the self-tensioning membrane is bonded to a frame (e.g., a rigid frame as shown in  FIGS. 1-3  and  6 A- 6 B, or a flexible frame as shown in  FIGS. 9A-9B ) using an adhesive. Depending on the composition of the self-tensioning membrane, heat may be applied to the membrane to bring the film to a tensioned state after attachment to the frame. Such a construction creates an outer bonded region and a tensioned inner region where the film can react to sound pressure waves and transmit that sound energy to the medium on the opposite side of the film. A double sided adhesive may be applied to the outer edge of the film, opposite the frame, such that the film is between the frame and the second adhesive layer. The additional adhesive acts as a bonding system and gasket when the frame is installed over an acoustic vent opening in a protective enclosure. Such a frame construction allows the self-tensioning membrane to exert the majority of tension force on the frame and not on the second adhesive layer bonded to the surface of a protective enclosure. Furthermore, the frame assembly allows the self-tensioning membrane to be easily handled during installation. 
     According to another embodiment of the disclosure, the outer edge of the self-tensioning membrane is bonded to a double-sided adhesive in such that an inner, unbound, region is formed. The assembly can then be installed over an acoustic vent opening in a protective enclosure. In this embodiment, the double sided adhesive is strong enough to resist the tension forces exerted upon the adhesive. 
     These and other features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view of an exemplary protective enclosure employing an exemplary sound transmissive cover; 
         FIG. 2  is a top view of an exemplary sound transmissive cover as detailed in an embodiment of the present invention; 
         FIG. 3  is a cross-sectional view of the exemplary sound transmissive cover shown in  FIG. 2 , taken along line  3 - 3 , where the exemplary sound transmissive cover is attached to the surface of a protective enclosure; 
         FIG. 4  is a bottom view of another exemplary sound transmissive cover as detailed in another embodiment of the present invention; 
         FIG. 5  is a cross-sectional view of the exemplary sound transmissive cover shown in  FIG. 4 , taken along line  5 - 5 , where the exemplary sound transmissive cover is attached to the surface of a protective enclosure; 
         FIG. 6A  is a view of another exemplary sound transmission cover in combination with another exemplary protective enclosure; 
         FIG. 6B  is a close-up view of the exemplary sound transmission cover shown in  FIG. 6A ; 
         FIG. 7  is a frontal view of the exemplary sound transmission cover shown in  FIG. 6 ; 
         FIG. 8  is a close-up frontal view of the exemplary sound transmission cover shown in  FIG. 7 ; 
         FIG. 9A  is a view of another exemplary sound transmission cover; 
         FIG. 9B  is a close-up view of area B shown in  FIG. 9A  when the exemplary sound transmission cover shown in  FIG. 9A  is attached to an exemplary protective enclosure; 
         FIG. 10  is a perspective view of another exemplary protective enclosure of the present invention; and 
         FIGS. 11A-11B  depict alternative constructions of outer surfaces of the exemplary protective enclosure shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     To promote an understanding of the principles of the present invention, descriptions of specific embodiments of the invention follow and specific language is used to describe the specific embodiments. It will nevertheless be understood that no limitation of the scope of the invention is intended by the use of specific language. Alterations, further modifications, and such further applications of the principles of the present invention discussed are contemplated as would normally occur to one ordinarily skilled in the art to which the invention pertains. 
     As seen in attached drawings and outlined herein, two embodiments of the protective material for acoustic transmission are generally shown in dimensions and configurations such that they are designed to be used as a sound-transmissive barrier in a loudspeaker enclosure. The protective material for acoustic transmission of the present disclosure is not limited to the embodiments illustrated as these depictions can be modified or adjusted without deviating from the scope of the invention. 
     As the terms are used herein, “protective material for acoustic transmission” may be interchanged with “self-tensioning membrane” which means a continuous sheet of material that will actively pursue a condensed state either by internal elastic force or by molecular realignment caused by external stimuli. 
     As the term is used herein, “rigid frame” means a sufficiently rigid structure that is formed from either a single part or parts and provides a support structure and adhesive location for the outer edge of the self-tensioning membrane while having a hollow central region where the membrane can move freely. The required stiffness of the rigid frame can be variable dependent on the amount of force exerted by the self-tensioning membrane. 
     As the term is used herein, “flexible frame” means a structure that is formed from either a single part or parts and provides a support structure for the self-tensioning membrane while having a hollow central region where at least portions of the membrane can move freely. 
       FIG. 1  is an external view of a rigid, protective enclosure  100 , designed to house a portable loudspeaker device (not shown), with an acoustic vent opening  102  in the lid  105  of the enclosure  100 .  FIG. 1  also illustrates the general installation location for a self-tensioning membrane  104 . The size, shape and location of the acoustic vent opening  102  could vary depending on the size of the protective enclosure  100  and the device enclosed. 
     An example of a protective enclosure  100  could be an injection molded waterproof case system where a portable loudspeaker device could be temporarily installed. Such a case system would be inherently waterproof, but the rigid protective structure would prohibit adequate sound transmission from within the case. Enabling sound transmission from within the case requires a sufficiently sized acoustic vent opening  102  to be cut into the lid  105  of the case  100 . A sound transmissive cover, as described in embodiments of the disclosure, could then be installed over the acoustic vent opening  102  to provide a barrier against liquid and particulate intrusion while transmitting sound from the interior to the exterior of the case  100 . 
       FIGS. 2 and 3  illustrate one embodiment of the disclosure where a sound transmissive cover  200  is constructed with a self-tensioning membrane  104  and a rigid frame  202 , where the membrane  104  and the frame  202  are bonded with an adhesive  302 . Such a construction creates an inner unbound region  106  where the self-tensioning membrane  104  can move in response to incoming sound waves. A double sided adhesive  304  applied to the outer edge  120  of the film  104 , opposite the rigid frame  202 , creates a construction such that the self-tensioning film  104  is now between the rigid frame  202  and the second adhesive layer  304 . The sound transmissive cover  200  can then be attached to the surface  308  of a protective enclosure  306 , where the double-sided adhesive  304  serves to create a gasket and bond between the self-tensioning membrane  104  and the surface  308  of a protective enclosure  306 . 
     The self-tensioning membrane  104  serves as a barrier to liquid and particulate entry while also transmitting sound from one side of the membrane  104  to the other. To provide sustained acoustic performance across varying environmental conditions and over the life of the sound transmissive cover  200 , the self-tensioning membrane  104  must have the ability to maintain or, at a minimum, regain tension. 
     The ability of the membrane  104  to maintain or regain tension is inherent only to certain classes of materials and, therefore, not all materials would be able to achieve the same self-tensioning effect. The self-tensioning membrane  104  as described in this disclosure could be composed of, but is not limited to, elastomeric materials such as thermoplastic polyurethane “TPU” or a group of polymer films that seek a condensed state due to molecular realignment. One group of molecularly oriented films, which seeks a condensed state due to molecular realignment, is commonly known as “shrink film.” Shrink films can be composed of, but are not limited to, polyolefins such as polyethylene or polypropylene, and poly-vinyl chloride “PVC”. 
     Whether the self-tensioning membrane  104  is composed of an elastomeric material or a film with shrink capabilities, the membrane  104  should desirably have the following properties: a film thickness in a range of about 5 to about 100 microns, preferably from about 5 to about 20 microns; and a mass in the range of about 1 to about 35 g/m 2 , preferably from about 1 to about 20 g/m 2 . Should the self-tensioning membrane  104  be composed of an elastomer, the material should desirably be able to stretch to an area greater than 5% of an original size. Should the self-tensioning membrane be a “shrink” film, the free shrinkage should desirably be greater than 5% of the original surface area, preferably greater than about 20% of the original surface area. 
     The rigid frame  202  of the present embodiment may, for example, be constructed from 0.019″ thick aluminum, where a flat aluminum sheet is die-cut to produce the frame shape. The self-tensioning membrane  104  may be adhered to the rigid frame  202  using a high-performance spray adhesive  302  although many other types of bonding materials could be chosen to provide a sufficiently strong bond. The self-tensioning membrane  104  of this embodiment may be a “shrink” film and thus be heated after bonding to the rigid frame  202  in order to achieve a tensioned inner region  106  where the film  104  can move in response to sound energy. The purpose of the rigid frame structure  202  is to support the tension forces exerted by the membrane  104 . 
     The double-sided adhesive  304  of the present embodiment may be a commercially-available, acrylic tape, although other types of bonding materials could serve the same function. The task function of the double-sided adhesive  304  is to create a durable bond and gasket between the self-tensioning membrane  104  and the surface  308  of a protective enclosure  306 . Such a bond would be required to resist external forces acting on the sound transmissive cover  200 . 
       FIGS. 4 and 5  illustrate another embodiment of the disclosure where a sound transmissive cover  200  is constructed from a self-tensioning membrane  104  and a double sided adhesive  304 . The sound transmissive cover  200  is also shown as it would be attached to the surface  308  of a protective enclosure  306 . This embodiment of the disclosure is very similar to that of  FIGS. 2 and 3 , but the self-tensioning membrane  104  is only bonded on one side and lacks the support of the rigid frame  202 . In such a construction, the double-sided adhesive  304  creates a sufficiently strong bond between the membrane  104  and protective enclosure  306  to resist all tension forces created by the self-tensioning membrane  104  and any external forces that may act on the membrane  104 . Such an embodiment of the disclosure requires the self-tensioning membrane  104  to either be pre-stretched before adhesion to the surface  308  of a protective enclosure  306 , if the membrane  104  is composed of an elastomer, or heated post installation, if the membrane  104  is an oriented film. This requirement is more demanding in installation and therefore the first embodiment of the disclosure is the preferred method. 
     In other embodiments, the self-tensioning membrane  104  may be mechanically attached to a component (e.g., lid  105 ) of a protective enclosure  100  with or without the use of adhesive  30 . As shown in  FIG. 6A , rigid frame  202  comprises (i) an outer frame member  203 , and (ii) an acoustic vent opening  204  extending through said rigid frame  202  and surrounded by said outer frame member  203 . In this embodiment, rigid frame  202  further comprises intermediate frame members  208 , which connect to outer frame member  203 , and divide acoustic vent opening  204  into multiple openings (e.g., in the embodiment shown, acoustic vent opening  204  is divided into eight separate openings). Intermediate frame members  208  provide additional support for self-tensioning membrane  104  (i.e., self-tensioning membrane  104  is not shown in  FIG. 6A , but would be positioned between rigid frame  202  and protective enclosure  306  and held in place via rigid frame  202 ). It should be noted that one or more of intermediate frame members  208  may be attached to portions of self-tensioning membrane  104  (i.e., via an adhesive), but typically, each of intermediate frame members  208  are not attached to self-tensioning membrane  104 , but provide support as needed if self-tensioning membrane  104  is forcibly moved towards and/or come into contact with intermediate frame members  208 . 
       FIG. 6B  provides a close-up view of the exemplary sound transmission cover  200  shown in  FIG. 6A . As shown in  FIG. 6B , exemplary sound transmission cover  200  comprises a groove  310  within surface  308  of protective enclosure  306 . Groove  310  extends along surface  308  so as to surround an acoustic grid opening  314  within protective enclosure  306 . 
       FIG. 7  provides a frontal view of the exemplary sound transmission cover  200  shown in  FIG. 6A . As shown in  FIGS. 7-8 , a front surface  214  of rigid frame  202  comprises a raised surface portion  210 , which has dimensions so as to correspond to and fit within groove  310  within surface  308  of protective enclosure  306  shown in  FIG. 6B . Rigid frame  202  further comprises attachment members  212  having hole  220  therein, which may be used to connect rigid frame  202  to surface  308  of protective enclosure  306  shown in  FIG. 6B , i.e., via corresponding attachment members  312  having hole  320  therein (e.g., via a screw (not shown)). 
     In yet another embodiment, the self-tensioning membrane  104  may be mechanically and/or adhesively attached to a flexible frame  402  (e.g., a gasket material  402 ) and/or a protective enclosure  100  with or without the use of adhesive  30  (see, for example,  FIG. 3 ). As shown in  FIG. 9A , flexible frame  402  comprises (i) an outer frame member  403 , and (ii) one or more acoustic vent openings  404  extending through said frame  402  and surrounded by said outer frame member  403 . In this embodiment, frame  402  further comprises intermediate frame members  408 , which connect to outer frame member  403 , and divide frame  402  into multiple openings (e.g., in the embodiment shown, acoustic vent opening  404  is divided into eight separate openings). Intermediate frame members  408  provide additional support for self-tensioning membrane  104 . It should be noted that one or more of intermediate frame members  408  may be attached to portions of self-tensioning membrane  104  (i.e., via an adhesive). Typically, in this embodiment, each of intermediate frame members  408  are attached to self-tensioning membrane  104  (i.e., via an adhesive), so as to provide support for self-tensioning membrane  104 . 
       FIG. 9B  provides a cross-sectional view of exemplary frame  402  in combination with protective enclosure  306 . As shown in  FIG. 9B , adhesive  304  may be used to adhesively bond frame  402  to protective enclosure  306  (and bond one or more of intermediate frame members  408  to portions of self-tensioning membrane  104  as discussed above). In other embodiments (not shown), exemplary frame  402  may be mechanically attached (e.g., via a screw (not shown) to sound transmission cover  200  as shown in  FIGS. 6A-6B , for example, in place of rigid frame  202 ) with one or more of intermediate frame members  408  adhesively bonded to portions of self-tensioning membrane  104  as discussed above. 
       FIG. 10  provides a perspective view of another exemplary protective enclosure  100  of the present invention. In this embodiment, exemplary protective enclosure  100  comprises a lid  105  with a single acoustic vent opening  102  therein and a protective membrane  104  extending over the single acoustic vent opening  102 . Exemplary protective enclosure  100  further comprises one or more side walls  141  (i.e., depending on the overall shape) extending from an upper surface  140  of lid  105  to a lower surface  142  of exemplary protective enclosure  100 . 
       FIGS. 11A-11B  depict alternative constructions of lower surface  142  of exemplary protective enclosure  100  shown in  FIG. 10 . In some embodiments, exemplary protective enclosure  100  shown in  FIG. 10  may comprise a single acoustic vent opening  102  therein (i.e., within upper surface  140 , but nowhere else). In other embodiments, exemplary protective enclosure  100  may comprise two or more similar or different acoustic vent openings  102  therein. As shown in  FIG. 11A , in some embodiments, lower surface  142  of exemplary protective enclosure  100  may further comprise an acoustic vent opening  102  therein, so that protective enclosure  100  comprises a total of two acoustic vent openings  102  therein (i.e., one within upper surface  140  and one within lower surface  142 ). As shown in  FIG. 11B , in other embodiments, lower surface  142  of exemplary protective enclosure  100  may further comprise two separate acoustic vent openings  102  therein, so that protective enclosure  100  comprises a total of three acoustic vent openings  102  therein (i.e., one within upper surface  140  and two within lower surface  142 ). 
     Other Embodiments 
     Protective Membranes 
     1. A protective membrane  104  comprising: a continuous sheet of self-tensioning polymeric film material  10  having (i) a first major sheet surface  11 , (ii) a second major sheet surface  12  opposite said first major sheet surface  11 , (iii) an outer sheet edge  13  extending along said first and second major sheet surfaces  11 / 12 , and (iv) an inner unbound sheet region  106  surrounded by said outer sheet edge  13 ; and a bonding material  30  extending along (i) said first major sheet surface  11  proximate said outer sheet edge  13  thereof, (ii) said second major sheet surface  12  proximate said outer sheet edge  13  thereof, or (iii) both (i) and (ii) so as to completely surround said inner unbound sheet region  106 , said continuous sheet of self-tensioning polymeric film material  10  providing a barrier to liquid and particulate material while enabling transmission of sound waves therethrough. 
     2. The protective membrane  104  of embodiment 1, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises an elastomeric material or a film with shrink capabilities. 
     3. The protective membrane  104  of embodiment 1 or 2, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises an elastomeric material. 
     4. The protective membrane  104  of any one of embodiments 1 to 3, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises an elastomeric material capable of being stretched to an area greater than 5% of an original area. 
     5. The protective membrane  104  of any one of embodiments 1 to 4, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises a thermoplastic polyurethane (TPU). 
     6. The protective membrane  104  of embodiment 1 or 2, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises a film with shrink capabilities. 
     7. The protective membrane  104  of any one of embodiments 1 to 2 and 6, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises a film having a free shrinkage of greater than 5% of an original surface area. 
     8. The protective membrane  104  of any one of embodiments 1 to 2 and 6 to 7, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises a film having a free shrinkage of greater than 20% of an original surface area. 
     9. The protective membrane  104  of any one of embodiments 1 to 2 and 6 to 8, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises a polyolefin or polyvinyl chloride (PVC). 
     10. The protective membrane  104  of any one of embodiments 1 to 2 and 6 to 9, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises a polyolefin. 
     11. The protective membrane  104  of any one of embodiments 1 to 2 and 6 to 10, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises polyethylene. 
     12. The protective membrane  104  of any one of embodiments 1 to 2 and 6 to 10, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises polypropylene. 
     13. The protective membrane  104  of any one of embodiments 1 to 2 and 6 to 9, wherein said continuous sheet of self-tensioning polymeric film material  10  comprises polyvinyl chloride (PVC). 
     14. The protective membrane  104  of any one of embodiments 1 to 13, wherein said continuous sheet of self-tensioning polymeric film material  10  has a film thickness ranging from about 5 microns (μm) to about 100 nm. 
     15. The protective membrane  104  of any one of embodiments 1 to 14, wherein said continuous sheet of self-tensioning polymeric film material  10  has a film thickness ranging from about 5 nm to about 20 nm. 
     16. The protective membrane  104  of any one of embodiments 1 to 15, wherein said continuous sheet of self-tensioning polymeric film material  10  has a film basis weight ranging from about 1.0 grams per meter squared (g/m 2 ) to about 35 g/m 2 . 
     17. The protective membrane  104  of any one of embodiments 1 to 16, wherein said continuous sheet of self-tensioning polymeric film material  10  has a film basis weight ranging from about 1.0 g/m 2  to about 20 g/m 2 . 
     18. The protective membrane  104  of any one of embodiments 1 to 17, wherein said bonding material  30  extends along either (i) said first major sheet surface  11  or (ii) said second major sheet surface  12 . 
     19. The protective membrane  104  of any one of embodiments 1 to 17, wherein said bonding material  30  extends along both (i) said first major sheet surface  11 , and (ii) said second major sheet surface  12 . 
     20. The protective membrane  104  of any one of embodiments 1 to 19, wherein said bonding material  30  comprises an adhesive. 
     21. The protective membrane  104  of any one of embodiments 1 to 20, wherein said bonding material  30  comprises a sprayable adhesive  30  (e.g., adhesive  302 ). 
     22. The protective membrane  104  of any one of embodiments 1 to 20, wherein said bonding material  30  comprises a double-sided adhesive tape  30  (e.g., adhesive  304 ). 
     23. The protective membrane  104  of any one of embodiments 1 to 22, wherein said bonding material  30  comprises (i) a first layer of a sprayable adhesive  30  (e.g., adhesive  302 ) along one of said first and second major sheet surfaces  11 / 12 , and (ii) a double-sided adhesive tape  30  (e.g., adhesive  304 ) along the other of said first and second major sheet surfaces  11 / 12 . 
     24. The protective membrane  104  of any one of embodiments 1 to 23, further comprising a frame  202 / 402 , said frame  202 / 402  comprising (i) an outer frame member  203 / 403 , and (ii) an acoustic vent opening  204 / 404  extending through said frame  202 / 402  and surrounded by said outer frame member  203 / 403 . 
     25. The protective membrane  104  of any one of embodiments 1 to 24, further comprising a frame  202 / 402  comprising (i) an outer frame member  203 / 403 , and (ii) an acoustic vent opening  204 / 404  extending through said frame  202 / 402  and surrounded by said outer frame member  203 / 403 , said continuous sheet of self-tensioning polymeric film material  10  being bonded to said frame  202 / 402  such that said inner unbound sheet region  106  of said continuous sheet of self-tensioning polymeric film material  10  is positioned over said acoustic vent opening  204 / 404 . 
     26. The protective membrane  104  of embodiment 25, wherein said continuous sheet of self-tensioning polymeric film material  10  is either (i) pre-stretched prior to being bonded to said frame  202 / 402  or (ii) heated after being bonded to said frame  202 / 402  so as to tension said inner unbound sheet region  106  of said continuous sheet of self-tensioning polymeric film  10 . 
     27. The protective membrane  104  of embodiment 25 or 26, wherein said frame  202 / 402  comprises a protective enclosure  100 , the protective enclosure  100  being sized so as to house a portable loudspeaker device (not shown). 
     28. The protective membrane  104  of any one of embodiments 25 to 27, wherein said frame  202 / 402  comprises a lid  105  of a protective enclosure  100 , the protective enclosure  100  being sized so as to house a portable loudspeaker device (not shown). 
     29. The protective membrane  104  of any one of embodiments 25 to 28, said frame  202 / 402  further comprising one or more intermediate frame members  208 / 408  extending between portions of said outer frame member  203 / 403 , said one or more intermediate frame members  208 / 408  dividing said acoustic vent opening  204 / 404  into two or more separate acoustic vent openings  204 / 404 . 
     30. The protective membrane  104  of any one of embodiments 25 to 29, wherein said frame  202  comprises a rigid polymeric material. 
     31. The protective membrane  104  of any one of embodiments 25 to 29, wherein said frame  402  comprises a flexible polymeric material. 
     32. The protective membrane  104  of any one of embodiments 25 to 29 and 31, wherein said frame  402  comprises a gasket  402 . 
     33. The protective membrane  104  of any one of embodiments 1 to 32, wherein said continuous sheet of self-tensioning polymeric film material  10  has a pore volume of less than about 15% (or any pore volume value between 0 and 15%, in increments of 0.01% (e.g., 0.08%), or any range of pore volume values between 0 and 15%, in increments of 0.01% (e.g., from 0 to 1.15%). Typically, continuous sheet of self-tensioning polymeric film material  10  has a pore volume of less than about 5% (or less than about 4%, or less than about 3%, or less than about 2%, or less than about 1%, or less than about 0.5% or 0%). 
     34. The protective membrane  104  of any one of embodiments 1 to 33, wherein said continuous sheet of self-tensioning polymeric film material  10  has a pore volume of less than about 10% (or any pore volume value between 0 and 10%, in increments of 0.01% (e.g., 0.08%), or any range of pore volume values between 0 and 10%, in increments of 0.01% (e.g., from 0 to 1.15%). 
     35. The protective membrane  104  of any one of embodiments 1 to 34, wherein said continuous sheet of self-tensioning polymeric film material  10  has a pore volume of less than about 5% (or any pore volume value between 0 and 5%, in increments of 0.01% (e.g., 0.08%), or any range of pore volume values between 0 and 5%, in increments of 0.01% (e.g., from 0 to 1.15%). 
     36. The protective membrane  104  of any one of embodiments 1 to 35, wherein said continuous sheet of self-tensioning polymeric film material  10  has an air permeability of at least 60 Gurley-seconds (or any air permeability value greater than 60 Gurley-seconds, in increments of 0.1 Gurley-seconds (e.g., 60.1 or 360.8 Gurley-seconds), or any range of air permeability values greater than 60 Gurley-seconds, in increments of 0.1 Gurley-seconds (e.g., from 60.1 to 3600.0 Gurley-seconds)). 
     37. The protective membrane  104  of any one of embodiments 1 to 36, wherein said continuous sheet of self-tensioning polymeric film material  10  has an air permeability of at least 120 Gurley-seconds (or any air permeability value greater than 120 Gurley-seconds, in increments of 0.1 Gurley-seconds (e.g., 120.1 or 360.8 Gurley-seconds), or any range of air permeability values greater than 120 Gurley-seconds, in increments of 0.1 Gurley-seconds (e.g., from 120.1 to 3600.0 Gurley-seconds)). 
     38. The protective membrane  104  of any one of embodiments 1 to 37, wherein said continuous sheet of self-tensioning polymeric film material  10  has an air permeability of at least 3600 Gurley-seconds (or any air permeability value greater than 3600 Gurley-seconds, in increments of 0.1 Gurley-seconds (e.g., 3600.1 Gurley-seconds), or any range of air permeability values greater than 3600 Gurley-seconds, in increments of 0.1 Gurley-seconds (e.g., from 3600.1 to 10000.0 Gurley-seconds)). 
     39. The protective membrane  104  of any one of embodiments 1 to 38, wherein said continuous sheet of self-tensioning polymeric film material  10  consists of said polymeric film material  10 , and said inner unbound sheet region  106  is free from any coating thereon or therein. 
     Protective Enclosures 
     40. A protective enclosure  100  sized to house a portable loudspeaker device, said protective enclosure  100  comprising: a protective enclosure case  150  (see, for example,  FIG. 10 ) comprising (i) a rigid protective structure  151 , and (ii) an acoustic vent opening  102  extending through said protective enclosure case  150  and surrounded by said rigid protective structure  151 ; and the protective membrane  104  of any one of embodiments 1 to 39 bonded to said protective enclosure case  150  such that said inner unbound sheet region  106  of said continuous sheet of self-tensioning polymeric film material  10  is positioned over said acoustic vent opening  102 . Other protective enclosures  100  of the present invention may comprise a protective enclosure  100  sized to house a portable loudspeaker device, wherein protective enclosure  100  comprising: a protective enclosure case  150  (see, for example,  FIG. 10 ) comprising (i) a rigid protective structure  151 , and (ii) an acoustic vent opening  102  extending through said protective enclosure case  150  and surrounded by said rigid protective structure  151 ; and a continuous sheet of self-tensioning polymeric film material  10  (e.g., as recited in any one of embodiments 1 to 39 with or without a bonding agent  30  attached thereto) bonded to (or otherwise attached to) said protective enclosure case  150  such that said inner unbound sheet region  106  of said continuous sheet of self-tensioning polymeric film material  10  is positioned over said acoustic vent opening  102 . 
     41. The protective enclosure  100  of embodiment 40 in combination with a portable loudspeaker device (not shown). 
     42. The protective enclosure  100  of embodiment 41, said portable loudspeaker device being positioned within said protective enclosure case  150 . 
     Methods of Making Protective Membranes 
     43. A method of making the protective membrane  104  of any one of embodiments 1 to 39, said method comprising: providing the continuous sheet of self-tensioning polymeric film material  10 ; and applying the bonding material  30  onto the continuous sheet of self-tensioning polymeric film material  10 . 
     44. The method of embodiment 43, wherein said applying step comprises applying the bonding material  30  along either (i) the first major sheet surface  11  or (ii) the second major sheet surface  12 . 
     45. The method of embodiment 43, wherein said applying step comprises applying the bonding material  30  along both (i) the first major sheet surface  11 , and (ii) the second major sheet surface  12 . 
     46. The method of any one of embodiments 43 to 45, wherein said method further comprises: bonding the continuous sheet of self-tensioning polymeric film material  10  to a frame  202 / 402 , the frame  202 / 402  comprising (i) an outer frame member  203 / 403 , and (ii) an acoustic vent opening  204 / 404  extending through the rigid frame  202 / 402  and surrounded by the outer frame member  203 / 403 , the continuous sheet of self-tensioning polymeric film material  10  being bonded to the frame  202 / 402  such that the inner unbound sheet region  106  of the continuous sheet of self-tensioning polymeric film material  10  is positioned over the acoustic vent opening  204 / 404 . 
     Methods of Making Protective Enclosures 
     47. A method of making the protective enclosure  100  of embodiment 40, said method comprising: providing the continuous sheet of self-tensioning polymeric film material  10 ; applying the bonding material  30  onto the continuous sheet of self-tensioning polymeric film material  10 ; and bonding the continuous sheet of self-tensioning polymeric film material  10  to the rigid protective structure  151  such that the inner unbound sheet region  106  of the continuous sheet of self-tensioning polymeric film material  10  is positioned over the acoustic vent opening  204 / 404 . 
     48. The method of making the protective enclosure  100  of embodiment 47, wherein said bonding step comprises (1) bonding the continuous sheet of self-tensioning polymeric film material  10  to a frame  202 / 402 , the frame  202 / 402  comprising (i) an outer frame member  203 / 403 , and (ii) an acoustic vent opening  204 / 404  extending through the frame  202 / 402  and surrounded by the outer frame member  203 / 403 , the continuous sheet of self-tensioning polymeric film material  10  being bonded to the frame  202 / 402  such that the inner unbound sheet region  106  of the continuous sheet of self-tensioning polymeric film material  10  is positioned over the acoustic vent opening  204 / 404  in the frame  202 / 402 , and (2) bonding the continuous sheet of self-tensioning polymeric film material  10 /frame  202 / 402  to the rigid protective structure  151 . 
     49. The method of any one of embodiments 46 to 48, said method further comprising: pre-stretching the continuous sheet of self-tensioning polymeric film material  10  prior to said bonding step. 
     50. The method of any one of embodiments 46 to 48, said method further comprising: heating the continuous sheet of self-tensioning polymeric film  10  after said bonding step so as to tension the inner unbound sheet region  106  of the continuous sheet of self-tensioning polymeric film  10 . 
     51. The method of any one of embodiments 47 to 50, said method further comprising: positioning a portable loudspeaker device (not shown) within the protective enclosure case  150 . 
     Methods of Using Protective Membranes 
     52. A method of transmitting sound, said method comprising: transmitting sound through the first and second major sheet surfaces  11 / 12  of (i) the protective membrane  104  of any one of embodiments 1 to 39 or (ii) the protective membrane  104  of the protective enclosure  100  of any one of embodiments 40 to 42. 
     53. The method of embodiment 52, said method further comprising: positioning a portable loudspeaker device (not shown) proximate one of the first and second major sheet surfaces  11 / 12 . 
     54. The method of embodiment 52 or 53, said transmitting step comprises transmitting sound from within a rigid protective structure  151  of a protective enclosure  100  such that sound waves pass through the inner unbound sheet region  106  of the continuous sheet of self-tensioning polymeric film material  10  to an exterior of the rigid protective structure  151 . 
     55. A method of water-proofing a portable loudspeaker device protective enclosure  100 , said method comprising: positioning the protective membrane  104  of any one of embodiments 1 to 39 over an acoustic vent opening  102  of the portable loudspeaker device protective enclosure  100 . 
     It should be understood that although the above-described protective membranes  104 , protective enclosures  100 , and methods are described as “comprising” one or more components or steps, the above-described protective membranes  104 , protective enclosures  100 , and methods may “comprise,” “consists of,” or “consist essentially of any of” the above-described components or steps of the protective membranes  104 , protective enclosures  100 , and methods. Consequently, where the present invention, or a portion thereof, has been described with an open-ended term such as “comprising,” it should be readily understood that (unless otherwise stated) the description of the present invention, or the portion thereof, should also be interpreted to describe the present invention, or a portion thereof, using the terms “consisting essentially of” or “consisting of” or variations thereof as discussed below. 
     As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains”, “containing,” “characterized by” or any other variation thereof, are intended to encompass a non-exclusive inclusion, subject to any limitation explicitly indicated otherwise, of the recited components. For example, a protective membrane  104 , a protective enclosure  100 , and/or method that “comprises” a list of elements (e.g., components or steps) is not necessarily limited to only those elements (or components or steps), but may include other elements (or components or steps) not expressly listed or inherent to the protective membrane  104 , protective enclosure  100 , and/or method. 
     As used herein, the transitional phrases “consists of” and “consisting of” exclude any element, step, or component not specified. For example, “consists of” or “consisting of” used in a claim would limit the claim to the components, materials or steps specifically recited in the claim except for impurities ordinarily associated therewith (i.e., impurities within a given component). When the phrase “consists of” or “consisting of” appears in a clause of the body of a claim, rather than immediately following the preamble, the phrase “consists of” or “consisting of” limits only the elements (or components or steps) set forth in that clause; other elements (or components) are not excluded from the claim as a whole. 
     As used herein, the transitional phrases “consists essentially of” and “consisting essentially of” are used to define a protective membrane  104 , a protective enclosure  100 , and/or method that includes materials, steps, features, components, or elements, in addition to those literally disclosed, provided that these additional materials, steps, features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention. The term “consisting essentially of” occupies a middle ground between “comprising” and “consisting of”. 
     Further, it should be understood that the herein-described protective membranes  104 , protective enclosures  100 , and/or methods may comprise, consist essentially of, or consist of any of the herein-described components and features, as shown in the figures with or without any feature(s) not shown in the figures. In other words, in some embodiments, the protective membranes  104 , protective enclosures  100 , and/or methods of the present invention do not have any additional features other than those shown in the figures, and such additional features, not shown in the figures, are specifically excluded from the protective membranes  104 , the protective enclosures  100 , and/or methods. In other embodiments, the protective membranes  104 , the protective enclosures  100 , and/or methods of the present invention do have one or more additional features that are not shown in the figures. 
     The present invention is further illustrated by the following examples, which are not to be construed in any way as imposing limitations upon the scope thereof On the contrary, it is to be clearly understood that resort may be had to various other embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the present invention and/or the scope of the appended claims. 
     EXAMPLE 1 
     Protective membranes and protective enclosures, similar to exemplary protective membranes  104  and protective enclosures  100  shown in  FIGS. 1-11B , were prepared. 
     While the specification has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention should be assessed as that of the appended claims and any equivalents thereto.