Abstract:
Stereo apparatus having angled speakers so as to direct sound at a desired angle relative to the ears of the listener. The disclosed arrangements enhance the stereo sound effect and provide accurate stereo imaging, as well as sound stage expansion, through the proper placement and orientation of speaker units relative to the ears of a listener. The speaker units may be positioned at optimum angles of incidence and distances relative to the ears of a listener. Adjustable positioning means are provided to enable control over the horizontal spatial dimension of the stereo sound. The speaker units may be fixed at a preset orientation, or pivotally mounted for positional adjustment by the listener. Speaker units and releasable mounts may be provided for attachment to eyeglass-style temple pieces for added convenience and comfort. A number of mounting arrangements for simplifying selection of the desired earphone angle are disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No.: 60/122,919, filed Mar. 5, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to headsets for sound reproduction, specifically headsets for accurately reproducing stereo sound and imaging, and, more particularly, to improvements in such stereo headsets, including expansion of the sound stage, and to solutions to some of the problems raised or not resolved thereby. 
     2. Description of the Related Art 
     Manufacturers of headsets have traditionally positioned the speaker elements either covering the ear, on the ear, or in the ear canal of the listener. These conventional placement methods create certain undesirable listening characteristics. Conventional headsets are often cited as being deficient in reproducing accurate stereo imaging and having limited sound stage. (The term “sound stage”, as used in audio or video sound recordings, generally refers to the left-right spread of the sound between the speakers in a playback system. Thus the greater or more expanded the sound stage, the closer the resemblance to the real performance in the case of an orchestra or band recording playback, for example.) The stereo image produced by conventional headsets is often criticized for having poor spatial dimension, lacking “sound stage” realism, and producing “sound in the middle of the head” imaging. Prolonged listening with conventional stereo headsets may produce feelings of pressure or even a sensation of heaviness in the ears. 
     The inferior sound performance and discomfort which accompany conventional headset designs stem from the fact that such designs prevent either ear from receiving signals from the stereo channel directed to the other ear. Therefore, each ear hears only one stereo channel. This arrangement eliminates the subtle clues employed by the brain in determining the location of each sound&#39;s point of origin, which are critical and essential to the accurate perception of stereo sound and imaging. 
     A headphone of the in-the-ear type has been proposed, in which a housing containing a speaker unit is inserted into the cavum concha of the listener&#39;s ear. As is described in U.S. Pat. No. 5,519,782, issued to Shinohara et al., this type of headphone provides an arrangement whereby the speaker/acoustic transducer is partially inserted into the ear. 
     A headphone combining the vertical in-the-ear type headset and the conventional flat-against-the-ear type headset has been proposed, in which the in-the-ear first acoustic transducer is mounted at right angles to the flat-against-the-ear second acoustic transducer. As is described in U.S. Pat. No. 5,333,206, issued to Koss, this type of headset is worn such that when the second transducer is flat against the ear in a conventional manner, the in-the-ear first transducer extends into the cavum concha in the listener&#39;s ear. 
     A conventional headset incorporating rotatable couplings between the earphone portions and the headband has been proposed, such that the earphone portions of the headset can rotate about the axis of the headband and thereby permit the headset to adapt to differently angled ears and also fold flat for more convenient transportation. As in the case of a headset with a single earphone, such an arrangement enables the earphone to be mounted adjacent either ear. As is described in U.S. Pat. No. 4,689,822, issued to Houng, this type of headset fails to address the deficiencies commonly encountered with conventional headset designs. 
     U.S. Pat. No. 3,900,707, issued to Hanson, provides a complex arrangement of mounted multiple speakers for enabling the reproduction of quadraphonic sound. A rather large and elaborate headgear is described having particularly-shaped cavities and particularly positioned speakers to introduce certain phase relationships in the sound that is reproduced. The overall size and complexity of the device described precludes its convenient and practical use and interferes with the activities and field of vision of the listener. In a word, this is a kluge. It does not address the problems solved by the present invention. 
     U.S. Pat. No. 4,027,113, issued to Matsumoto, et al. provides a coupling means for mounting the earcup to the headband portion of a conventional headset. The disclosed coupling means comprises a partial ball-and-socket mount to provide universal pivoting such that the earcup may fit and adapt to any type of ear. The listening effects provided by such design present all of the stereo imaging deficiencies encountered with conventional headset design. 
     A headset arrangement for holding the earphones flat against the ears is provided for in U.S. Pat. No. 3,919,501, issued to Cech et al. The against-the-ear arrangement provided therein fails to address the listening deficiencies commonly encountered with conventional headset design. 
     This invention relates to improvements to the stereo headset apparatus set forth above and to solutions to some of the problems raised or not resolved thereby. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a stereo headset for use by a listener. Various arrangements in accordance with the invention enhance the quality of stereo sound and enable accurate stereo imaging through the proper placement and orientation of speakers relative to the ears of a listener. Accurate presentation of stereo sound and imaging, as well as expanded sound stage, is achieved through the proper positioning and orienting of the speakers rather than by means of audio propagation techniques or signal manipulation methods. 
     Particular arrangements of the present invention are effective in reproducing high-quality stereo sound and imaging and expanded sound stage through the application of principles of physics relating to sound and its properties. These arrangements project stereo sound waves from the speaker units to the ears of a listener under conditions of optimum angularity, embodying the ideal distance from the ear, and under controlled conditions in order to achieve stereo sound of superior quality with heightened image realism. 
     In accordance with the present invention, a speaker assembly is oriented at an angle to and spaced from the auditory canal rather than being generally in line therewith when the assembly is in place on the ear of the listener, as is commonly found in conventional headset designs. Through the configuration of the present invention, the speaker units may be positioned at optimum angles of incidence relative to the auditory canals of a listener such that the sound waves will diffract into the auditory canal. Furthermore, by providing adequate distance between the speaker assemblies and the listener&#39;s ears, the present invention greatly heightens the stereo sound and imaging accuracy, thereby reducing the troubling stereo imaging phenomenon commonly encountered with conventional headset designs. 
     By increasing or decreasing the angle of the speaker units relative to the listener&#39;s ear, the horizontal spatial dimension of the stereo sound may be narrowed or spread. This feature is not provided by any of the references cited herein. 
     The angle of projection of the speaker units of the present invention may be preset at a fixed angle generally suitable for most listeners, or each speaker unit may be adjustably mounted. Such adjustable mounting of the speaker units provides means by which angular adjustments may be performed by the listener to yield the most desirable stereo effect. For those who prefer the conventional flat-against-the-ear mode, such an orientation is provided by disclosed embodiments of the invention. 
     Angular adjustment means may comprise cross-axis pivoting joints, spline and shaft assemblies, ball and socket joints, and other variable positioning means. Such adjustable angular positioning means may be fixed or secured once the speaker units have been adjusted to the angle desired by the listener. Such angular adjusting means and securing means are well known in the art but, as used in connection with the disclosed embodiments of the present invention, constitute equivalent arrangements for the practice of the invention. 
     In marked contrast to conventional stereo headset design, the present invention positions the speaker units adjacent to the auricle of the listener&#39;s ear without covering or obscuring the ear, such that the ear is located in the near field of the speaker units where sound clarity and imaging are most pronounced. Through this design, the stereo headset of the present invention avoids covering the auricle in order to prevent the head-in-a-barrel sensation, all the while permitting the free exchange of sound waves between the speaker units and both of the listener&#39;s auditory canals. The speaker configuration and positioning of the present invention provide a more natural acoustical setting for the unrestricted dispersion of sound waves in marked contrast to conventional headset designs. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention may be realized from a consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view showing a pair of earphones according to a first embodiment of the present invention; 
     FIG. 2 is a perspective view of a headset comprising a variant of the earphones of FIG. 1 in which like elements are designated by like reference numerals with the prime designation added; 
     FIG. 2A is a schematic diagram illustrating an alternative version of a portion of the arrangement of FIG. 2; 
     FIG. 3 is a partial perspective view showing a headset according to a second embodiment of the present invention; 
     FIGS. 4A and 4B are, respectively, side elevational and top views of a left-side mounting arrangement for an earphone of the present invention; 
     FIGS. 5A and 5B are schematic sectional views showing further details of the pivoted mounting arrangements of FIGS.  4 A and  4 B; 
     FIG. 6A is a schematic perspective view showing another particular mounting arrangement for an earphone of the present invention; 
     FIGS. 6B and 6C are partial sectional views of the arrangement of FIG. 6A, showing the earphone in respective conventional flat-against-the-ear and angled operational positions; 
     FIGS. 7A,  7 B and  7 C are respective left side elevational and top views of another particular arrangement in accordance with the invention showing a particular toggle spring mount; and 
     FIGS. 8A and 8B are, respectively, side elevational and top views of a left-side mounting arrangement for an earphone in still another embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will hereinafter be described with reference to the drawings. 
     FIG. 1 of the accompanying drawings shows a pair of interconnected earphones  20  according to a first embodiment  10  of the present invention. Generally “U”-shaped members  14  comprise anterior arms  16  and posterior arms  18  designed to fit over the ears on the head of a listener, between the pinna and the head on each side. 
     Speaker units  20  are attached to anterior arms  16  at an angle Θ relative to the plane of the ears of a listener, which plane parallels an imagined vertical plane bisecting the head of a listener into symmetrical halves. Speaker cords  21 ,  22  connect speaker units  20  to an audio signal source (not shown). Element  23  is a slidable friction keeper to hold the cords  22  under slight tension to keep the speaker units from moving out of position. 
     FIG. 2 of the accompanying drawings shows a headset according to a variant  10 ′ of the embodiment of FIG.  1 . Apparatus  10 ′ includes a headband portion  12 , slidably adjustable to generally fit over the head of a listener. The headband portion  12  connects to a pair of generally “U”-shaped members  14 ′ which comprise anterior arms  16 ′ and posterior arms  18 ′ designed to fit over the ears on the head of a listener, between the pinna and the head on each side. Speaker units  20 ′ are attached to anterior arms  16 ′ at an angle Θ relative to the plane of the ears of a listener, which plane parallels an imagined vertical plane bisecting the head of a listener into symmetrical halves. Speaker cords  21 ′,  22 ′ connect speaker units  20 ′ to an audio signal source (not shown). 
     As shown in FIG. 2A, which depicts a positioning member  52  of an earphone assembly  50  such as is shown in FIG. 4A, the member  52  may be attached to adjustable headband  12  by fastening members  53 . Members  53  may be screws or rivets or any comparable fasteners. 
     FIG. 3 depicts a headset apparatus constructed according to a second preferred embodiment of the present invention. Speaker units  20  are secured to hangers  30  having spring clip mounts  42  for releasable attachment to eyeglass temple pieces  40  of a pair of eyeglasses to be worn by a listener. The remaining portion of the eyeglasses is signified by the broken line  44  extending between the terminations of the temple pieces  40 . The invention provides for the positioning of speaker units  20  at a distance from the ears of a listener, and at an angle Θ relative to an imagined vertical plane bisecting the head of a listener into symmetrical halves. 
     FIGS. 4A and 4B, respectively a left-side view and top view, depict an adjustable earphone mounting arrangement for a user&#39;s left ear. When the adjustable earphone mounting arrangement of FIGS. 4A and 4B is considered as an arrangement to be worn at the left ear, the pivot arrangement would be positioned slightly forward of the ear and the earphone  54  would be angled outwardly and slightly forward of the external auditory canal, or meatus, of the wearer&#39;s ear. However, the arrangement of FIGS. 4A and 4B could as well be worn on the right ear, in which case the pivoting arrangement would be at the back of the ear and the earphone  54 , when angled outwardly, would be slightly behind the external auditory canal, or meatus, of the ear. The path of the sound from the angled earphone  54  would still be directed at the opening of the auditory canal. In each case, a mirror image unit may be provided for the other ear in order to develop the desired stereophonic effect. 
     In these figures, the assembly  50  is shown comprising a mounting piece  52  shaped to fit over the left ear of the user, and an earphone  54  incorporating a speaker  54   a  in a frame  55  coupled to the earpiece  52  by a pivoted mounting arrangement  56 . The mounting  56  comprises a pair of outwardly directed ears  58  on opposite sides of an extended portion  60  of the earphone frame  55 . A pivot pin  62  extends between the members  58  and through the portion  60 . A further extension of the earphone frame  55  provides a lever member  64  elliptically shaped to provide a finger tab  66  for ready manipulation of the earphone and frame between conventional flat-against-the-ear position  68 , indicated by the solid outline earphone structure in FIG. 4B, and angled operating position  59 , indicated by the broken outline  69  in FIG.  4 B. 
     FIG. 5A is a cross-sectional view showing one version of the pivot arrangement  56  of FIG. 4A having friction cam surfaces to hold the selected angular position of the earphone. In the arrangement of FIG. 5A, the mounting piece  52  is provided with an outwardly extending portion  72  in the area between the projecting ears  58 . This portion  72  is provided with a shoulder portion  74  which is shaped to mate with a matching shoulder portion  76  on the extended portion  60  of the earphone frame  55 . The two mating surfaces develop frictional engagement to hold the earphone and frame at whatever angle is selected by the user. The portions  74 ,  76  serve as a position stop to define the limit of the angle at which the earphone  54  may be opened, relative to the earpiece  52 . Thus, the user may very easily move the earphone  54  between a position flat against the ear, indicated by the numeral  68  in FIG. 4B, and the angled position, indicated by the numeral  69  in FIG.  4 B. 
     An alternative mounting arrangement also providing for variability in the angle at which the earphone is positioned for listening by the user is illustrated in FIG.  5 B. This mounting arrangement incorporates a fluted cam with a spring keeper to establish a plurality of preset angles for the earphone. In this figure, the lower curved surface  80  of the pivotable mounting  56 A is shown provided with a series of recesses  82 , and a spring  84  having at least one detent member  86  is affixed to the earpiece  52 . With this arrangement, the user may readily pivot the earphone unit to prescribed angular positions relative to the ear mounting member  52  by simply rotating the earphone with frame  55  until the detent  86  seats in one or another of the recesses  82 . 
     FIGS. 6A,  6 B and  6 C illustrate yet another detent structure for quickly positioning an earphone  54  between a flat-against-the-ear position, as in FIGS. 6A and 6B, and an open position, as shown in FIG.  6 C. The earphone frame  55 ′ is supported on a generally flat spring  102  which itself is supportably mounted in a mounting base  104  attached to the earpiece  52 . 
     This arrangement further includes an angle adjustment lever  106 . The lever  106  is a spring member attached to the earpiece  52  at one end  108  by a rivet  109  or other similar attachment means and providing at the other end a curved finger grip  110 . The spring  102  has a central aperture  103  through which the angle adjustment lever  106  extends. At the point adjacent the aperture  103 , the lever  106  is provided with a projecting locking ramp  112 . When the earphone  54  is positioned generally parallel to the earpiece  52  as illustrated in FIGS. 6A and 6B, the locking ramp  112  engages the spring  102 , locking the two pieces in the stored position. To move the earpiece  54  to the operative position shown in FIG. 6C, a slight force on the finger grip portion  110  of the lever  106  serves to release the spring  102  from the locking ramp  112  so that the spring  102  and the earphone  54 , speaker  54   a  and frame assembly assume the position shown in FIG.  6 C. If the earphone  54  is again moved to the position in FIG. 6B, the locking ramp  112  becomes positioned above the spring  102  such that it again serves to retain the spring in the flat-against-the-ear position. 
     FIGS. 7A,  7 B and  7 C illustrate still another mounting position for an earphone assembly  50  including an earpiece or ear mount  52 , an earphone  54  with speaker  54   a  and an earphone frame  55 ′. As best shown in FIGS. 7B and 7C, the earpiece  52  is generally L-shaped with a right angled portion  122  at one end. A spring member  124  is attached to the support portion  122  as shown. This spring  124  is configured and attached to the frame  55 ′ in a way which establishes a toggle mounting structure. The spring  124  is constructed of spring material cut in a generally U-shaped configuration  126  (see FIG.  7 A). The two sides  128  of the U-shaped spring  124  are attached to the frame  55 ′ by fasteners  130 , such as rivets or screws, which distort the spring  124  into a stressed configuration. As seen in FIG. 7A, the outer ends of the side pieces  128  are forced closer together than at the base. This causes the spring  124  to exhibit a toggle effect in positioning the earphone assembly  54  relative to the earpiece  52 . Thus, when the earphone  54  is in the conventional flat-against-the-ear setting shown in FIG. 7B, the spring  124  is in an outwardly curved or convex configuration. Moving the earphone  54  away from the earpiece  52  causes the spring  124  to snap into a concave curvature, as shown in FIG.  7 C. Thus, the earphone  54  may readily be moved between the positions of FIGS. 7B and 7C with very little applied force so that the earphone assumes the position desired by the user. 
     FIGS. 8A and 8B are schematic representations, side and top views, of still another version of the earphone mounting arrangement of the present invention. This version is similar to the others described hereinabove in stereophonic performance and result except that it is less costly to manufacture because of its simple construction. As with the other representations, particularly that depicted in FIGS. 4A and 4B, the unit of FIGS. 8A and 8B can be worn on either the left ear, in which case the earphone is aimed at the auditory canal from slightly forward of the ear, or the right ear, where the earphone would be angled from slightly behind the ear. 
     FIGS. 8A and 8B show a unitary earpiece and earphone mounting assembly  150  comprising an integral mounting and support member  160  to which is affixed an earphone  154  incorporating a speaker  154 A. The member  160  comprises a shaped earpiece portion  152  fashioned for placement over the ear, a portion  156  curved in a general U-shape to establish the desired angle of the earphone and speaker, and a mounting portion  158  to which the earphone is attached by fasteners  159 . It has been found that the best sound effects are achieved with an angle of about 27°, preferably within the range of 25° to 30°, although angles outside this range develop an enhanced stereophonic sound but perhaps less pronounced. These fasteners may be screws, rivets, fused plastic plugs, or any other suitable fastening elements. A wire  162  is shown extending from the lower end of the earpiece  152  (right hand side of FIG. 8A) in phantom outline to the point  164  where it enters the earphone. The support member  160  is formed of a malleable material, preferably soft aluminum, so that there is some adjustability of the angle of the earphone by simply bending the portion  156 . However, the material is sufficiently stiff that it will readily maintain whatever position is established to support the earphone  154  at the selected angle relative to the auditory canal when the assembly is in place on the listener&#39;s ear. 
     Thus the various embodiments shown and described herein provide stereophonic earphones arranged for special mounting with respect to a listener&#39;s ears such that the sound from the earphone speakers reaches the listener with enhanced stereophonic richness, expanded sound stage, and with heightened image realism. The undesirable effects encountered by some listeners from the use of flat-against-the-ear speakers are avoided. This improvement in overall result is achieved without significant added expense. 
     Although there have been described hereinabove various specific arrangements of STEREO HEADSET WITH ANGLED SPEAKERS in accordance with the invention for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art should be considered to be within the scope of the invention as defined in the annexed claims.