Abstract:
An acoustical device includes a housing operative to be placed proximate to an ear of a wearer and a front volume partially defined by the housing. A controlled leakage path is disposed to acoustically and selectively couple the front volume of the housing with an exterior of the device.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to audio applications, and more specifically, to acoustical devices such as headphones. 
       BACKGROUND 
       [0002]    Fully closed headphones (circum-aural or supra-aural) are generally not seen in the current market. By fully closed it is meant that there are no venting or controlled acoustic leakages from the front volume to the outside, from the back volume to the outside or connecting the front and back volumes. 
         [0003]    There are various reasons why a fully closed headphone acoustical architecture may not be the preferred acoustical system.
       (1) The fully closed front volume will cause a DC pressure on the headphone driver, potentially causing permanent deformation of the diaphragm   (2) The fully closed acoustical system will be very susceptible to uncontrollable leakages occurring when the headphones are in use. A leakage may be introduced between the ear pad and the wearer&#39;s head and/or ear due to hair or glasses.       
 
       SUMMARY 
       [0006]    According to an embodiment an acoustical device includes a housing operative to be placed proximate to an ear of a wearer and a front volume partially defined by the housing. A controlled leakage path is disposed to acoustically and selectively couple the front volume of the housing with an exterior of the device. 
         [0007]    According to another embodiment an acoustical device includes a housing, a back volume arranged in the housing, a driver arranged in the back volume, and a front volume arranged in the housing. A controlled leakage path, arranged such that the front volume is communicative with an exterior of the device via the controlled leakage path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts: 
           [0009]    The single FIGURE shows a cut-away view of a headphone device. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    As discussed above there are several disadvantages to fully closed headphones. However, there are also several advantages for preferring a fully closed headphone acoustical architecture.
       (1) By fully closing the back volume, the back volume can be minimized in size as no account need to be taken of the mechanical and acoustical dimensions of venting. This minimized back volume allows for more freedom in the industrial design;   (2) The ear cup housing may have uncontrolled leakages (e.g. due to mechanical buttons to operate the headphones, hinges that couple the earcup to the headband structure, etc.). By fully closing the back volume behind the driver, these uncontrolled leakages will not influence the headphones audible frequency response.       
 
         [0013]    What is desired is a closed acoustical device having a controlled leakage that benefits from the advantages of a fully closed systems but that does not include the disadvantages. 
         [0014]    Referring to the FIGURE, a cut-away view of a headphone  100  is shown as including a driver  102 . The driver  102  is a transducer for converting an electrical signal into audible sound. The driver is communicatively connected to an audio source (not shown) to receive the electrical signals. 
         [0015]    A back volume V b    104  is a fully closed (sealed) volume (cavity) behind the driver  102 . A front volume V f    106  is a volume (cavity) in front of the driver  102 . The front volume  106  couples the driver  102  acoustically to a wearer&#39;s ear when worn. An ear pad (cushion)  108  may be a circum or circa aural ear pad, for creating an acoustical seal with the wearers head and/or ear, which are represented by the line  101 . 
         [0016]    An ear cup housing  110  is the external portion of the ear cup, which encloses, among other elements, the headphone driver  102 , the back volume  104 , and in some embodiments electronics for audio processing and/or wireless communication in embodiments with wirelessly connected headphones. 
         [0017]    The acoustical device of the FIGURE introduces a controlled leakage path  112  into a fully closed acoustical architecture, which couples the front volume  106  to the outside ambient air  114 . The back volume  104  remains fully closed such that the only controlled leakage path  112  is from the front volume  106  to the outside. 
         [0018]    This controlled leakage path  112  makes the closed headphones less susceptible to uncontrolled leakages occurring between the ear pad  108  and the wearers head and/or ear. 
         [0019]    The controlled leakage path  112  lowers the risk of damaging the driver  102  diaphragm when the headphones  100  are in use. 
         [0020]    This controlled leakage path  112  is dimensioned as such that the audible sound is affected in the very low frequencies. This can for example be achieved by dimensioning the controlled leakage path  112  as a long but narrow, hollow tube where the length of the tube is greater than the width of the tube. The hollow tube has a large acoustical mass. 
         [0021]    The mechanical element introducing the controlled leakage path  112  may in some embodiments also include an additional resistive acoustical member  116 , in the form of for example a mesh or woven material. This resistive acoustical member  116  may introduce further control over the acoustical behavior of the front volume and the controlled leakage path  112 . 
         [0022]    The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 
         [0023]    While the preferred embodiments to the invention have been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.