Abstract:
An acoustic noise reduction accessory device is attachable to or integral with a personal computer or other electronic equipment. The device reduces acoustic noise emitted from the rear of the equipment, in particular the acoustic noise from fans. The device comprises an acoustic barrier or shielding member. The barrier is shaped in various forms external to the computer or integrally extending from its back around one or more fans of the computer so as to reduce airflow minimally. Acoustic absorbing material is layered upon the acoustic barrier and may be combined with vibration-absorbing material. The barrier may be shaped from a solid or flexible member(s) to accommodate different-sized electronics and formed to include baffles and structures to direct airflow while absorbing noise. Also it may be made adjustable by one or more slidable members. The device is easily assembled and collapsible for storage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of application Ser. No. 11/346,719, filed 2006 Feb. 2, now abandoned, which application claims priority of my U.S. Provisional Application Ser. Nos. 60/650,431, filed 2005 Feb. 4, and 60/723,796, filed 2005 Oct. 5, which are incorporated herein by reference in their entirety. 

   BACKGROUND 
   1. Field 
   The field is acoustic noise reduction of electronic equipment, in particular, acoustic reduction of fan noise emitted from personal computers and other electronic equipment with negligible air flow impediment. 
   2. Prior Art 
   Computers and other electronic equipment which utilize air circulating or cooling fans and other electronic devices generate noise. This noise, usually emitted from the rear of such devices, can be annoying, bringing about a desire to minimize such noise. Previous solutions have attempted to create lower-noise-generating fans. However, such fans, when used as replacements, are inconvenient to attach, requiring tools and extra elements such as screws or bolts. Disassembly of the computer or the equipment is also often needed. Once installed, such a fan is inconvenient to remove as this requires further time and tools. Other techniques include installing an external device, such as a “PC hood,” made of plastic, onto the backs of PCs to cover the fans. However, such devices reduce airflow and air pressure of the fans. In addition, such devices require tools and cannot be easily disassembled or adapted to different sizes of electronic equipment. 
   Therefore there is a need for an acoustic noise reducing device to reduce noise generated by fans without significantly minimizing the necessary airflow from the fans. There is also a need for such a device which can be quickly assembled and which does not require tools or extra implements to assemble, which can accommodate different sizes of electronic equipment, and which can be easily transported. 
   ADVANTAGES 
   It is accordingly an advantage of one or more aspects to reduce acoustic noise generated by fans associated with personal computers, PCs, and other electronic devices. A further advantage is to provide minimal to negligible airflow reduction through the electronic device. Another advantage is to provide an acoustic reduction or silencer accessory device that can be attached to electronic equipment very quickly and easily, for instance in about 90 seconds or less, and that attaches externally without the need to power off or disassemble anything on the equipment. 
   Other advantages of one or more aspects are to provide such a device which is adjustable to accommodate different widths and sizes of computers, to provide a reusable device that can accommodate different and upgraded PCs to avoid purchase of any new devices when a new PC is purchased, to provide a device that installs without other elements or tools, to provide a device that is easily transported, and that can be recycled and that is environment friendly. 
   Still further advantages of one or more aspects will become apparent from a consideration of the ensuing description and drawings. 
   SUMMARY 
   According to one embodiment an acoustic noise reduction accessory device is attachable or made integral to a personal computer or other electronic equipment. The device can be used with a low-acoustic-noise fan, as the device will further reduce the acoustic noise emitted from the fan. The device reduces acoustic noise emitted from the rear of the computer in general and in particular reduces the acoustic noise from the air-circulating fans. 
   The device allows the airflow rate to be maintained, avoiding a 90-degree turn of airflow with virtually no reduction in airflow rate. For some embodiments there are configurations where the airflow will need to be either turned or restricted to some minimal amount, resulting in only minimal airflow reduction. The device installs in short amount of time, for example 90 seconds or less, without tools, bolts or screws and is adjustable to devices of different sizes. 
   In one embodiment, the device comprises an acoustic barrier or shield member. The barrier is shaped in various forms externally of the computer or integrally extending from the back portion of the computer around the one or more fans. The acoustic barrier member causes minimum to negligible airflow reduction by leaving air pathways from the fans. In addition, an acoustic absorbing material is layered upon the acoustic barrier and may be combined with vibration-absorbing material in various forms and shapes. The barrier may be shaped to accommodate different sized electronic devices and formed to include baffles and structures to direct airflow while absorbing noise. 
   In other embodiments, the device may be made adjustable by one or more slidable members or can be made adjustable by the material and shape used for the acoustic barrier. The device is adjustable for different widths of the tower chassis of personal computers and/or the positioning of the fans. 
   The device can be installed without disassembly and reassembly of the PC and it does not require disconnection of any equipment cables. The device simply attaches to the external part of existing personal computer or electronics without tools or extra pieces. Furthermore, the device may be removed from the equipment easily and minimized or collapsed for transporting or storing the device or minimizing packaging size, thus saving on space and costs. In addition, components of the device may be manufactured from recyclable materials. 

   
     DRAWINGS 
       FIG. 1   a  shows an isometric view of a noise-reducing device separate from a computer prior to attachment, according to one embodiment. 
       FIG. 1   b  is an isometric view of the device of  FIG. 1   a  assembled to the back of the computer. 
       FIG. 2  shows an isometric view of a configuration of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 3  shows an isometric view of the device as it is assembled onto a computer illustrating an extension from the rear of the computer, according to another embodiment. 
       FIG. 4  shows an isometric view of the device as it is assembled onto a computer illustrating a semi-circular structure, according to another embodiment. 
       FIG. 5  shows an isometric view of the device as it is assembled onto a computer illustrating a semi-circular structure and extending along the sides of the computer, according to another embodiment. 
       FIG. 6  shows an isometric view of the device as it is assembled onto a computer illustrating a semi-circular structure according to another embodiment. 
       FIG. 7   a  shows an isometric view of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 7   b  shows the device of  FIG. 7   a  fully opened, according to another embodiment. 
       FIG. 8  shows an isometric view of the device as it is assembled onto a computer illustrating the device extending to the bottom of the computer, according to another embodiment. 
       FIG. 9  shows a back view of the device of  FIG. 8 . 
       FIG. 10  shows an isometric view of the device assembled onto a computer, extending to the bottom of the computer, according to another embodiment. 
       FIG. 11   a  shows an isometric view of the device assembled onto a computer, illustrating noise absorbing plates, according to another embodiment. 
       FIG. 11   b  shows a back view of the device of  FIG. 11   a.    
       FIG. 12   a  shows an isometric view the device assembled onto a computer, illustrating a reflector partially covering the end opening of the device, according to another embodiment. 
       FIG. 12   b  shows an isometric back view of the device of  FIG. 12   a.    
       FIG. 13  shows an isometric view of the device made integral to a computer, according to another embodiment. 
       FIG. 14   a  shows an isometric view of a configuration of the device as it is assembled onto a computer, according to another embodiment. 
       FIG. 14   b  shows an exploded isometric view of the device of  FIG. 14   a.    
       FIG. 14   c  shows a back view of the device of  FIG. 14   a.    
       FIG. 15   a  shows an isometric view of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 15   b  shows a partial top cross-sectional view of the device of  FIG. 15   a , taken at the  15   b - 15   b  line. 
       FIG. 15   c  shows an exploded isometric view of the device of  FIG. 15   a.    
       FIG. 16   a  shows an isometric view of the device as it is assembled onto a computer, illustrating a slide rail structure, according to another embodiment. 
       FIG. 16   b  shows a top view of the device of  FIG. 16   a.    
       FIG. 17   a  shows an isometric exploded view of the device as it is assembled onto a computer, illustrating a slide rail structure, according to another embodiment. 
       FIG. 17   b  shows a detail side view of the detail  17   b  of  FIG. 17   a.    
       FIG. 17   c  shows a top view of the device of  FIG. 17   a , through the cantilevered piece. 
       FIG. 18  shows an isometric view of the device made integral to a computer, according to another embodiment. 
       FIG. 19   a  shows an isometric view of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 19   b  shows a side view of the device of  FIG. 19   a.    
       FIG. 20   a  shows an isometric view of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 20   b  shows a side view of the device of  FIG. 20   a.    
       FIG. 21   a  shows an isometric view of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 21   b  shows a top view of the device of  FIG. 20   b.    
       FIG. 21   c  shows a front view of the device of  FIG. 20   a  with the device open and extended. 
       FIG. 21   d  shows a partial top view of the device in  FIG. 21   c  with the device open and extended. 
       FIG. 22   a  shows an isometric view of the device as it is assembled onto a computer according to another embodiment. 
       FIG. 22   b  shows a back view of the device of  FIG. 22   a.    
   

   REFERENCE NUMERALS 
   
     
       
             
             
           
         
             
                 
             
           
           
             
               5 
               acoustic noise reduction device 
             
             
               10 
               acoustic barrier (shield) 
             
             
               20 
               acoustic absorbing material 
             
             
               30 
               vibration absorbing material 
             
             
               40 
               hook-and-loop (h&amp;l) material or fastener 
             
             
               50 
               double sided tape 
             
             
               60 
               acoustic absorbing material plates 
             
             
               70 
               hard base material 
             
             
               80 
               straps 
             
             
               90 
               high-friction vibration absorption material 
             
             
               95 
               wall 
             
             
               100 
               PC or other electronic device 
             
             
               110 
               fans 
             
             
               120 
               door - barrier 
             
             
               130 
               hinges 
             
             
               140 
               slide or guide rails 
             
             
               160 
               side panel h&amp;l fastener 
             
             
               200 
               solid cantilever panel 
             
             
               210 
               flexible composite panel 
             
             
               220 
               composite panel 
             
             
                 
             
           
        
       
     
   
   DETAILED DESCRIPTION 
   FIGS.  1   a  and  1   b —Upside-Down U-Shaped ANR 
     FIGS. 1   a  and  1   b  show a first embodiment of an acoustic noise-reduction (ANR) device, cover, or hood  5  attached to an electronic device such as a personal computer (PC)  100 . Device  5  can be attached to the PC with a variety of different types of attachments. These comprise double-sided tape, a hook-and-loop (h&amp;l) fastener  40 , stretch straps or adjustable straps which wrap around the PC, magnets, the weight of device  5  itself, and other appropriate attachment means. 
   In a preferred embodiment, device  5  comprises a sheet of acoustic reflecting material  10  having an inner surface upon which a lining of a sheet of acoustic absorbing material  20  is placed. Acoustic reflecting material  10  will also be referred to as acoustic (noise) barrier, reflector, or shield interchangeably. Naturally, the more reflector  10  weighs per unit area, the better a barrier it will be. Reflector  10  may comprise sheet metal or other metal types, plastics, rubber, copper or metal filled rubber, wood, processed wood, leather, vinyl, any other acoustic reflecting (shielding) material, or a combination of these materials. Reflector  10  or other parts of the device which are positioned on the sides of the PC may include or be lined with vibration absorbing material  30  or acoustic absorbing material  20 . 
   Acoustic absorbing material  20  will also be referred to as acoustic noise reduction material or absorber. Absorber  20  may be attached to reflector  10  by any known method, such as sewing, adhesive, bonding, clipping, stapling, glue-gun-heated adhesives, or any other of several commonly known methods. Absorber  20  is placed on the back, fans side, of the PC. As stated, absorber  20  is accompanied or lines reflector  10  (also referred to as shielding or an acoustic barrier). 
   Absorber  20  may be selected from materials comprising foam, fiberglass, rubber, batting material, open-cell melamine foams, polyurethanes, urethanes, thermoplastics, and any other type of acoustic absorbing material or combination of these materials. Absorber  20  may have a variety of surface textures and contours and may have a shape other than a flat surface on the inside of reflector  10  where the absorption takes place. Such surfaces may be in the form of triangular wedges (horizontal or vertical or a combination of this), pyramids, semi-dome and valley shapes; which may be in a repetitive geometric shape. Such a surface may also be in the shape of totally random hills and valleys such as those similar to landscape or iceberg hills and valleys. Absorber  20  reduces acoustic noise by absorbing it as a sponge absorbs a liquid. It reduces the noise by transforming the air pressure waves of the noise into vibration energy and in turn transforming this energy into heat energy, thus dissipating part of the sound and thereby reducing the noise level). 
   Reflector  10  reflects the sound back to absorber  20  for further noise reduction by absorption in absorber  20 . Some acoustic noise will escape this second absorption process, back into the atmosphere, and will be reflected to the wall on the other side of reflector  10  and the same process will take place again. This acoustic noise energy will continue to be reflected back and forth, losing energy with each reflection, until it leaves the device through the openings at a reduced noise level. 
   As stated, in lieu of or in combination with sound absorber  20 , vibration absorbing material  30  may be placed on the inside surface of reflector  10  by double-sided adhesive tape  50  or bonding material. Vibration absorber  30  has high-performance damping characteristics. It may comprise polyurethanes, urethanes, thermoplastics and other damping materials such as damping foams and combinations thereof. 
   Acoustic noise is generated in all directions from the fan or fans in PC  100 . Some of the embodiments are structured to 1) encompass the fan(s) with noise absorption materials, but yet allow enough air passage ways for minimal air flow loss, and 2) encompass the fan(s) in the form of a cylinder, box, or the like with both ends open to minimize air flow loss, with acoustic absorbing materials surrounding the air flow, thus minimizing the air flow loss. The embodiments are configured for assembly on the back of PCs, or other electronic devices, where the fans are located. 
   FIG.  2 —Full-Length ANR Device 
     FIG. 2  shows the device covering the majority of the sides of PC  100  and extending (cantilevering over) beyond the back of PC  100 . This configuration has a cross-sectional shape of an upside-down U. Absorber  20  is provided on the inside of device  5  in the section beyond the back, as shown in  FIG. 1   a . Either vibration reduction  30  or sound absorber  20  may be positioned between the sides of the PC and the device as shown in  FIG. 1   a . This configuration is attached to the PC from the top and sides and sits off the ground. 
   FIG.  3 —Cantilevered Half-Length ANR Device 
     FIG. 3  shows an embodiment of device  5  extending beyond the back of PC  100 . This configuration does not cover the sides of the PC as in  FIG. 2  above. This configuration also has the cross-sectional shape of an upside-down U. Absorber  20  is on the inside of the device in the section beyond the back as shown in  FIG. 1   a . This configuration is attached to the PC from the top and sides and sits off the ground. 
   FIG.  4 —Cantilevered Vertical Semi-Tube ANR Device 
     FIG. 4  shows a configuration of device  5  as a semicircular shape attached to the sides and cantilevers over the back. It extends higher than the top of PC  100 . The top and bottom of the device are open for airflow. This embodiment does not cover the sides of the PC. The device is made of all flexible materials or substantially all flexible materials to be bent to a shape by the user. This configuration is attached to the PC from the top and sides and sits off the ground. 
   FIG.  5 —Cantilevered Vertical Semi-Tube with Side Covering ANR Device 
     FIG. 5  shows a configuration of device  5  similar to the one in  FIG. 4 . Here the sides of PC  100  are covered with either sound or vibration absorber  20  or  30  for more acoustic reduction. The device is made of all flexible materials or substantially all flexible materials to be bent to shape by the user. This configuration is attached to the PC from the top and sides and sits off the ground. 
   FIG.  6 —Friction-Attached Horizontal Cantilevered Semi-Tube ANR Device 
   In  FIG. 6 , high-friction, vibration-absorption material  90  is fixed to the inside bottom of the sheet metal and it holds the device onto the PC by interference fit and friction. Material  90  is attached by bonding, double sided tape, or sheet metal bending. This configuration is manufactured of a flexible hard material for reflector  10 . Examples of such flexible hard materials are steel or plastic. The device is configured as one piece that will wrap around the PC for an interference fit. The ends will be composed of high-friction, vibration-absorption material  90  with a friction fir to help hold the device onto the PC. Material  90  is flexible enough to fit different standard widths but yet has enough force caused by the interference fit and friction to hold it to the PC and preferably without any other type of attachment devices. Absorber  20  is on the inside of this device. This configuration is attached to the PC from the top and sides and sits off the ground. 
     FIGS. 7   a  and  7   b —Flexible Side and Cantilevered Upside Down U-Shaped ANR Device 
     FIG. 7   a  shows an embodiment of device  5  engaged with PC  100 . Here the device covers the majority of the sides and extends (cantilevers over) beyond the back of the PC. This configuration has a cross-sectional shape of an upside-down U. This embodiment shows three panels of reflector or barrier  10  which may be integrally a part of the barrier or connected to each other by attachments means. This configuration is made of all flexible material for adjusting to different PC widths and also for folding for cheaper shipping costs. An acoustic noise reduction material is provided on the inside of the device in the section beyond the back. There may either be vibration reduction or acoustic noise reduction between the sides of the PC and the device. This configuration is attached to the PC from the top and sides and sits off the ground. 
     FIG. 7   b  illustrates the device unfolded and lying flat on its outside, with the inner surface exposed. Sections of the device are made of a flexible material to bend around the edges of the PC or device. In one embodiment, reflector  10  is made of a flexible material such as rubber. 
   In another embodiment, only the sections which need to bend are made of a flexible material. These sections of flexible material are shown between the segments with vibration absorber  30 . Material  70  provides structural strength and helps maintain the shape of the flexible device. Material  70  is placed on the top area of the PC and is affixed to the PC. It holds the weight and maintains the shape of the back cantilevered end of the device, behind the fans. 
   FIGS.  8  and  9 —Horizontal Floor Standing ANR Device 
     FIG. 8  shows a configuration of device  5  similar to the configuration in  FIG. 3  and illustrates how device  5  sits on the floor. Device  5  has a slot at the bottom for cables and is made of two separate L-shaped pieces of reflector  10 , making it adjustable for PCs of different widths. 
     FIG. 9  shows the cross section of device  5  and the acoustic absorption material as well as the acoustic reflecting material on its outside. These materials overlap so that they can be adjusted for PCs of different widths. 
   FIG.  10 —Vertical Floor Standing ANR Device 
     FIG. 10  shows a configuration of a device which is similar to the one of  FIG. 2 . The device is turned 90 degrees and sits on its end on the same surface on which that PC  100  sits. The device has a sloped back and a slot at the bottom for cable outlet. Although not shown to be adjustable, the device can be made from two pieces of reflector  10  and made adjustable as in the device of  FIG. 8 . 
     FIGS. 11   a  and  11   b —Side And Cantilevered Upside Down U-Shaped ANR Device with Horizontal Baffles 
     FIG. 11   a  shows a configuration of a device  5  similar to the one in  FIG. 2 . The device has two added horizontal acoustic absorption plates  60  placed in the back. These plates further enhance the acoustic absorption of the device. In  FIG. 11   b , acoustic absorbing material plates  60  comprise absorber  20  located in a horizontal position in the back of the device. Plates  60  may or may not have reflector  10  incorporated. Plates  60  are fixed to the vertical sides of the device by either use of a h&amp;l fastener  40 , sewing, bonding onto the sides, or other equivalent attachment means. 
     FIG. 12   a  and  12   b —Side Cantilevered Upside Down U-Shape ANR Device with Vertical Baffle 
     FIG. 12   a  shows a device similar to the one in  FIG. 2 . It comprises an added vertical acoustic absorption plate  60  placed at the end opening of the device. The plate may be attached by means described above in relation to the plates  60  in  FIG. 11   a , or can be made integral to reflector  10 . 
     FIG. 12   b  shows an isometric view of the device with absorber  20  and also vertical plate  60  placed at the end of the device. 
   FIG.  13 —Integrated ANR Device 
     FIG. 13  shows a configuration of a device similar to the one in  FIG. 3 . The device is built into the sheet metal of the chassis of PC  100 . Absorber  20  is placed on the inside of the device. 
     FIGS. 14   a - 14   c —Cantilevered ANR U-Shaped Device with One Door 
     FIG. 14   a  shows a device which covers some of the sides of PC  100  and extends or cantilevers out beyond the back of the PC. This configuration has a cross-sectional shape of an upside-down U. Absorber  20  is positioned on the inside of the device in the section beyond the back of PC  100 . Either vibration absorber  30  or absorber  20 , as shown in  FIG. 14   b , may be positioned between the sides of PC  100  and reflector  10 . Device  5  is attached to the PC from the top and both sides and sits off the ground. Device  5  has the following features:
         1) It can be adjusted for different widths of personal computer chassis as the device slides through slide or guide rails  140  as shown in  FIG. 14   b  where barriers  10  are adjustable for fitting atop a personal computer chassis;   2) It can be made collapsible by hinges  130  for compact storage and shipping;   3) It has a door  120  which provides further acoustic reduction and which may be opened or closed during use, as shown in  FIG. 14   c.          
   Device  5  may be assembled using components made of plastic, acrylic, combinations thereof, or other suitable material along with an adhesive to attach the different components. These components include hinges  130 , the sides, the top, rails  140 , and back door  120 . The components may also be manufactured using injection molded or thermoformed plastic. Absorber  20  may be attached using double-sided tape, special adhesive, or absorber  20  may be manufactured with double-sided adhesive already attached. As shown in the back view of device  5  of  FIG. 14   c , door  120  may include absorber  20  on the inside surface of door  120 . The device may be attached to the personal computer chassis using h&amp;l fastener  40  or other similar attachment means as shown in  FIG. 14   a.    
     FIGS. 15   a - 15   c —Cantilevered U-Shaped ANR Device with Two Doors 
     FIG. 15   a  shows a device which is similar to the one of  FIG. 14   a  with the exception of the configuration of back doors  120 . Device  5  has two or more overlapping doors  120  but with a gap between the doors for an air passage from fans  110 , as shown in the top cross-sectional view of  FIG. 15   b . Doors  120  pivot on hinges  130  and facilitate the reduction of acoustic noise. Doors  120  may have absorber  20  on the surfaces facing the fans. Doors  120  may be positioned as shown or moved to hang on the opposite sides such that the airflow path is first straight out then turns in the right hand direction thereby leaving a larger space from the fans to the outermost door  120 . This device is adjustable for different personal computer widths and is also collapsible.  FIG. 15   c  shows reflector  10  are made adjustable along slide rails  140  and collapsible by hinges  130  as shown. Doors  120  can bend all the way back (270°) to become flush and parallel to the side walls of reflector  10 . The top parts or top panels of reflector  10  are hinged at  130  to the side parts of reflector  10  and slide over one another at the top. They are also bendable 90° downward when collapsed for disassembly, allowing ease of storage or shipping at lower costs. 
     FIGS. 16   a - 16   b —Two-Sided Slide-Rail-Adjustable ANR Device 
     FIGS. 16   a  and  16   b  show a device  5  which is adjustable in width from both sides. Two acoustic barriers  10  are placed on slide rails  140  and slide to the outside for width adjustment. These two barriers comprise slides at the top surface of a hard base material  70  connected to barrier  10 , which hang on slide rails  140  on the inside surface of top cantilevered piece  200 . Material  70  may be made of plastic or any other solid material. The two barriers  10  comprise flexible composite side pieces  210 . Air escapes through the gap between the two flexible side pieces  210  which curve. Flexible piece  210  is a composite of flexible barrier  10  and absorber  20 . Back piece  220  serves to further absorb acoustic noise coming out of the gap and comprises a composite of reflector  10  and absorber  20 . Pieces  210  and  220  are a combination of the acoustic noise barriers and the acoustic absorption materials. A variation of this embodiment may incorporate the sliding mechanism and overlapping barriers as described in  FIG. 14  above. 
     FIGS. 17   a - 17   c —One Side Slide-Rail Adjustable ANR Device 
     FIG. 17   a  shows a device  5  which is adjustable in width in a similar fashion to the device of  FIG. 16   a . In this device one side of the acoustic barrier slides while the other side stays fixed. Hard slide material  70  slides on slide rails  140 . Cantilevered panel  200  is attached to the personal computer using a h&amp;l fastener  40 . It is further positioned in place by two side solid wall panels  95 . Each of walls is approximately a 2.5 cm (one inch) high solid panel  95  which stretches along the bottom outer edge of panel  200  and along the upper outer edge of a flexible panel  210 . Wall  95  stretches beyond slide panel  70  and panel  200  to further position this device. Panel  95  is attached to the side of the PC by an attachment means such as a h&amp;l fastener  160 . Reflector  10  and absorber  20  are attached to panel  95  using h&amp;l fastener  40 , shown in  FIG. 17   b . Reflector  10  and absorber  20  may extend downward for more than 30.5 cm (12 inches). In this configuration, reflector  10  and absorber  20  may come as a single flexible composite panel  210 . A variation of this embodiment may incorporate the sliding mechanism and overlapping barriers as described in  FIG. 14 . 
     FIG. 17   b  is the view taken from  FIG. 17   a  showing the detail of panel  210  with panels  95  and  200 . The connection is made by h&amp;l fastener  40 . Panel  210  comprises reflector  10  and absorber  20 .  FIG. 17   c  shows a partial top view of the device of  FIG. 17   a , through the cantilevered panel and illustrates the positions of the adjustable acoustic barriers and the path of airflow. 
   FIG.  18 —Two-Door Integrated ANR Device 
     FIG. 18  shows a device  5  configured as an integral part of personal computer chassis  100 . The walls of device  5  comprise reflectors  10 . The insides of reflectors  10  are lined with absorber  20 . These walls may not extend all the way to the floor as far as the rest of the chassis. At the end of one of these walls is a first door  120  on hinges  130  with absorber  20  on the inside of this door. Also a second door  120  is mounted on the other side, closer to fans  110  than first door  120 , which also has acoustic noise absorber  20  on the inside. Doors  120  allow air to pass between them. Also a gap may be provided between doors  120 . 
     FIGS. 19   a - 19   b —Bottom Air Outlet ANR Device 
     FIG. 19   a  shows a device  5  which comprises a cantilevered solid panel  200  that sits on top of PC  100 . It is similar to the device of  FIG. 17 . The device does not cover the connectors of the PC but is adjusted to focus on the fan side. Acoustic barrier  10  is adjustable to fit different sized personal computers and it is also adjustable to locate the best position next to the fan location for the inner side of acoustic barrier/absorption material composite panel  220 . Side panel h&amp;l fastener  160  may be used to engage wall  95  of first barrier  10  against the PC sides. Reflector  10  slides along a first set of slide rails  140  which are connected to the underside of cantilevered panel  200 . Below first reflector  10  is second reflector  10  of composite panel  220  extending vertically downward and having a hard material  70  at the top surface. Second reflector  10  is adjustable along a second set of slide rails  140  connected to the underside of first reflector  10 . By sliding hard material  70  into the second set of slide rails  140 , second reflector  10  is adjusted to the position of the fans. 
     FIG. 19   b  is a side view of the device and shows the configuration of reflectors  10 . An air gap between cantilevered panel  200  and first reflector  10  is provided for airflow. Reflectors  10  may comprise composite  220  or a flexible composite piece. 
     FIGS. 20   a - 20   b —One-Side Slide-Rail Adjustable ANR Device with Baffles 
     FIG. 20   a  illustrates an embodiment of device  5  which focuses on the fans but not the connector area of PC  100 . This embodiment is similar to the device of  FIG. 19  and  FIG. 17 . The device is adjustable for different PC widths and it is able to adjust for a best location of the inner acoustic noise barrier and absorption material composite panel  220 . The device works by taking the airflow on a 90° laminar air flow turn for minimum airflow loss. Depending upon the configuration, the airflow may turn in other directions such as down or up. This reduces the air noise because there is no single line for the noise to leave the device, except at the bottom. At the exhaust section at the far end are one or more acoustic baffles  60  to further reduce the noise. Baffles  60  are made of absorber  20  or composite panel  220  of reflector  10  and absorber  20 .  FIG. 20   b  illustrates a side view of the device. Reflector  10  of panel  220  is slidably engaged with cantilevered panel  200  by slide rails  140  to adjust to the location of the fans. 
     FIGS. 21   a - 21   d —Top Covered Flexible Cantilevered Vertical Semi-Tube ANR Device 
     FIG. 21   a  shows an embodiment of the device made of a flexible material and is similar to the device of  FIG. 4 . A flexible cover  210  and the sides are made of a solid material for a small portion of both ends. These solid ends are used to hold the device to the rear sides of PC  100  using an attachment means such as h&amp;l fastener  40 . Flexible cover  210  comprises mostly flexible material which can be shaped to fit a personal computer of almost any width. Cover  210  includes fold-over parts, flaps, or tabs, shown in  FIGS. 21   b ,  21   c , and  21   d . These may be used to cover the top area behind the PC to reduce acoustic noise. The fold-over parts comprise reflector  10  and may have some acoustic absorption material on the inside surface. The fold-over pieces have many sections to allow this device to fit over personal computers of different widths and still cover the top without leaving any openings. The flexibility of the device allows it to be wrapped around itself or folded for reduced cost of shipment, delivery, and storage.  FIG. 21   b  shows the device from a top view with the fold-over pieces folded over.  FIG. 21   c  is a front view of the device in an open position with the pieces of cover  210  extended upward.  FIG. 21   d  is a top view of part of the device of  FIG. 21   c ; it shows the top view of the pieces of cover  210  extended, and further shows reflector  10  and absorber  20  attached to the inner surface. 
     FIGS. 22   a - 22   b —Rectangle Tube with Baffles 
     FIG. 22   a  illustrates an embodiment of device  5  which focuses on the area of the fans. Acoustic side wall reflectors  10  also include absorber  20 ,  FIG. 22   b . The device comprises one or more baffles or baffling partitions  60  between side reflectors  10  for reducing acoustic noise. Baffles  60  are placed vertically and have absorber  20  on their surfaces. Baffles may also be placed horizontally or at other angles or in any type of grid shape. Other examples of configurations for the baffles may be in the form of square, honeycomb, triangular, vertical, horizontal, or any combination thereof.  FIG. 22   b  is a back view of device  5  engaged on PC  100  and illustrates absorber  20  on side wall reflector  10  and baffle  60 . 
   RAMIFICATIONS AND SCOPE 
   While the description and drawings show exemplary embodiments with specific configurations, those of ordinary skill in the art will recognize that these embodiments can be realized in other specific forms. Thus the description and the drawings should be considered illustrative and not limiting. Many variations are possible and those of ordinary skill will be able to practice such other embodiments without undue experimentation. E.g., any of the embodiments described may have small breather air release openings with baffles to reduce the acoustic noise escaping from the openings. In addition, such baffles may comprise a box baffle structure of small elongated, tube like shaped holes or other shaped openings for further noise absorption. As an example, the ratio of the length to diameter of these elongated holes is greater than three for better absorption. 
   Thus the scope of the present patent is not limited merely to the specific exemplary embodiments, but rather is indicated by the appended claims and their legal equivalents.