Abstract:
A fitting provided for earbud-type personal audio speakers may be formed as a homogeneous, integral component molded from an elastomeric polymer, such as silicone, urethane, or other elastomeric resins. A sleeve fitted to the speaker engages the fitting to the speaker, while ribs extending from the sleeve terminate in flutes conformal to an ear canal of a user. Axial insertion of the fitting and speaker into an ear of a user results in localized deflection of flutes and ribs in order to accommodate size and shape of an ear canal, resulting in transmission of sound from the speaker directly through the sleeve into an ear canal of a user, while also permitting environmental sounds to pass along a parallel path over the outside of the sleeve, between the ribs.

Description:
RELATED APPLICATIONS 
     This application: claims the benefit of U.S. Provisional Patent Application Ser. No. 61/579,596, filed on Dec. 22, 2011; which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. The Field of the Invention 
     This invention relates to sound speakers and, more particularly, to novel systems and methods for earbud-style, miniature or personal audio system speakers. 
     2. The Background Art 
     Music, podcasts, and other audio materials are now available to listeners. With the advent of the ipod™ and other MP3 audio players, individuals can carry with them gigabytes of data representing audio files for their listening desires. Personal audio devices have given rise to a plethora of speaker systems requiring very low power and fitted to a user. Such systems include headsets, earbuds, and the like. These speaker systems are very light weight, require very low power, and require very little space in most circumstances. 
     Pedestrians on the street, drivers in vehicles, and individuals at their work stations may often be found listening to their choice of music or other audio materials. This has become a traffic and safety issue in certain circumstances. For example, a pedestrian walking on a street needs to be aware of certain sounds in the environment. Public transportation agencies spend tremendous amounts of advertising dollars educating the public as to safety around mass-transit rail systems. An individual who cannot hear a coming commuter train, particularly quiet light-rail types of systems, may step into the path of a train, approach too close to the tracks, or otherwise be endangered because the speaker systems of an audio player block out other sounds. 
     Typically, a speaker system based on earbud technology includes a speaker that transmits sound directly into the outer ear channel of a user. Typically, a plug surrounds the central sound channel. Thus, not only is the sound directed immediately into the outer ear channel, other sounds are blocked out. Thus, the earbuds act not only as speakers but also as earplugs to cut out surrounding sound. 
     Thus, an individual who is listening to music or other audio materials not only has the volume of the sound obscuring any environmental sound sources but also has the effect of an ear plug blocking out any sounds other than those emanating from the speaker. 
     It would be an advance in the art to develop a speaker that is safer, by permitting bypass of certain sounds in order to allow a user to still detect environmental sounds affecting safety. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including an apparatus having flutes that fit within the outer channel of an ear of a user, having apertures between the flutes. A sound channel is typically directed along the center of the apparatus, with the flutes extending away therefrom in order to support the apparatus in the outer ear channel of a user. 
     Apertures are sized to provide passage of sounds having a wavelength suitable for safety. Thus, apertures may have one dimension of about ⅛ inch or less, and another dimension of over a ¼ of an inch to about ½ inch. Typically, the apparatus will be provided with a sleeve surrounding the sound channel. The sleeve fits over the housing of a speaker system. The speaker system may include a housing around a speaker itself, as well as a stem that transitions the electrical connections with electronics and eventually connects to a cord. 
     In certain embodiments, the housing may provide a shank adapted to secure into the sleeve. The speaker may contain electrically active elements operated in response to electrical signals passed through a cord into the speaker. The shank and the sleeve each surround the channel or lumen that carries sound from the speaker directly into the ear channel of a user. In some embodiments, the flutes may be supported and maintained a distance away from the sleeve in order to provide pressure against the inside surface of an outer ear channel of a user in order to maintain the apparatus firmly positioned. 
     In certain embodiments of apparatus and methods in accordance with the invention, a speaker may be provided having an interface specifically fitted to hold or secure a shank on the speaker. Deforming and resilience help interface between the comparatively harder plastic of a speaker and the comparatively softer and more sensitive tissue in an outer ear canal of a user. The shank includes a hollow center channel (lumen) that propagates sound waves into the interface. The interface may be thought of as a fitting that surrounds the speaker and provides the interface between a user and the speaker. Accordingly, the interface may typically be formed of a comparatively soft and flexible elastomeric polymer material. The speaker will typically be contained in a housing of comparatively harder and more rigid material, such as a metal, hard plastic, or the like. 
     In one contemplated embodiment, the interface (i.e. fitting) may include a sleeve configured as a cylindrical element having fins radiating outward therefrom and extending along at least a portion of the length of the sleeve. Each of the fins will typically terminate at its outermost radius by becoming, or terminating in, a flute. 
     By flute here is meant a broader based portion of material having a comparatively larger area in contact with an outer ear canal of a user. The flutes thus remediate the pressure that might otherwise be exerted by the comparatively narrower or thinner ribs. Thus, whereas a rib might exert a comparatively larger pressure over a smaller area, that same force will generate a comparatively smaller pressure over a larger area when passed through a flute to the skin lining the outer ear canal of a user. 
     The length of a fin along the sleeve, as well as the thickness circumferentially of the fin in a circumferential direction around the sleeve may be designed according to the size of the canal expected to be fitted by the fitting, and the pressure expected to be suitable for comfort for a user. 
     For example, the ribs may be formed of an expanded polymeric foam, such as an expanded elastomeric polymer material. Thus, the ribs may be comparatively softer and more flexible than the housing, instead approximating the tissue of the ear of a user. Moreover, the ribs may be comparatively thinner in the circumferential direction, and sized in thickness in an aspect ratio with radial height selected to initiate column buckling. 
     For example, a comparatively thinner rib will deflect by buckling, yet the flute, having a larger area in contact with an outer ear canal of a user may still remain oriented thereagainst. Accordingly, column buckling of the rib provides relief in the backing force urging each flute against the wall of the outer ear canal. 
     In certain embodiments, the polymer from which the interface is formed may be molded. For example, injection molding has been found suitable and various elastomeric materials have proven suitable. Elastomeric materials of those which maintain a certain resilience and deflect elastically, completely recovering upon removal of an applied stress. Polyurethane, silicone, and other synthetic elastomeric polymers have been found suitable. 
     The path of sound waves emanating from the speaker passes through the central canal of the shank and into the central canal of the interface. Thus, the interface directs sound waves directly into the outer ear canal of a user, toward the eardrum. Meanwhile, parallel paths are formed to propagate environmental sounds through channels formed by each pair of adjacent fins and the intervening portion of the sleeve. The outer wall in such a channel may be a combination of the flutes and the wall of the outer ear canal of a user. 
     In the contemplated embodiments, the dimensions for the thickness, length along the sleeve, and radial height from the sleeve to the flute for each rib may be selected to be identical to all others. In an alternative embodiment, these may vary. Nevertheless, in one currently contemplated embodiment, the interface may be made point symmetric having a plurality of ribs and their corresponding flutes, radially opposite one another about a circumference of the interface. 
     Accordingly, the characteristic length may include each dimension across or along a channel between the ribs. Characteristic lengths may relate to the frequency and wavelength of sound propagated. Thus, the channels may tend to filter out longer wavelengths that do not match the characteristic lengths (e.g., circumferential width, radial height, and axial length) of the bypass channels along the outside of the sleeve. 
     In certain embodiments, the flutes may be spaced apart to provide more or less distance therebetween. Meanwhile, the flutes may be sized in thickness to provide more or less distance therebetween. Nevertheless, it has been found effective to provide about twenty five percent of the circumferential distance in open space between flutes. This permits the flutes to move toward one another, closer together and the ribs to deflect to accommodate that deflection or movement by the flutes. Accordingly, the flutes maintain open the channels defined by the adjacent ribs and intervening sleeve in each case. 
     In some embodiments, the ribs may actually deflect circumferentially and tip over. To the extent, that a rib does so deflect, it may leave behind a channel nevertheless. Thus, the channels need not all be identical in shape or size about the entire circumference of the fitting. 
     In some embodiments, it has been found suitable to provide a rim interconnecting the flutes at their front end (insertion end) near the outlet of the sound channel of the sleeve, at the rear (speaker end) of the fitting, or both. In certain embodiments, it has been found that the deflection suitable for comfortable fitting of the interfacing fitting with the outer ear canal of a user is best served without a rim, or with rimless flutes that are free to move with the deflection of the ribs in multiple dimensions. In this way, no rim need remain to enforce the spacing between flutes. Accordingly, the flutes may move closer together with circumferential deflection of the ribs, thus providing stabilization, a comfortable fit, and channel maintenance. This buckling or distortion of ribs minimizes the force applied by the resilient ribs and flutes against the wall of the outer ear canal of user. 
     The fitting thus provides two parallel paths for sound. While orienting the shank (e.g., outlet channel) of the speaker to propagate sound waves directly into the outer ear channel of a user, the interface also establishes, defines, and provides outer channels. Environmental sound passes around the sleeve and speaker, through channels defined by adjacent ribs and their intervening sleeve portion. Sound waves propagate directly into the outer ear channel of a user. 
     It has been found that two significant properties affect the sound quality perceived by a user of the ear bud or personal earphone type of speakers. First, is providing a direct line of sound propagation from a speaker into an outer ear channel of a user. Second is occlusion or blocking of environmental sounds. However, in certain environments, environmental sound is critical to safety. Thus, by providing the environmental sound channels around the outside surface of the sleeve, and the propagated sound from speakers from the inside channel along the interior of the sleeve, both environmental and propagated audio sound are provided to a user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
         FIG. 1  is a frontal perspective view of one embodiment of an apparatus in accordance with the invention; 
         FIG. 2  is a rear perspective view thereof; 
         FIG. 3  is front elevation view thereof; 
         FIG. 4  is a rear elevation view thereof; 
         FIG. 5  is a top plan view thereof; 
         FIG. 6  is a bottom plan view thereof; 
         FIG. 7  is a right side elevation view thereof; 
         FIG. 8  is a left side elevation view thereof; 
         FIG. 9  is a front perspective view thereof one embodiment of speaker housing system; 
         FIG. 10  is a rear perspective view thereof suitable for securing a fitting such as the audio-bypass safety earbud fitting; 
         FIG. 11  is a rear perspective view of an alternative embodiment of a sleeve of a fitting in accordance with the invention. 
         FIG. 12  is a frontal perspective view of a fitting having discrete apertures distributed over the outer wall of the fitting; 
         FIG. 13  is a front perspective view of an alternative embodiment of a fitting in accordance with the invention; 
         FIG. 14  is a rear perspective view thereof; 
         FIG. 15  is a front perspective view of an alternative embodiment for a fitting in accordance with the invention; 
         FIG. 16  is an alternative embodiment thereof, using a serrated or undulating edge on selected flutes thereof; 
         FIG. 17  is a perspective view of a one embodiment of a fitting in accordance with the invention; 
         FIG. 18  is a frontal perspective view of an alternative embodiment of a fitting in accordance with the invention; 
         FIG. 19  is an alternative embodiment of a fitting having flutes without a surrounding rim; 
         FIG. 20  is a front elevation view thereof; 
         FIG. 21  is a front elevation view of the apparatus of  FIG. 18 , showing distortion that may typically occur when positioned in place 
         FIG. 22  is a frontal perspective view of one embodiment of an apparatus in accordance with the invention; 
         FIG. 23  is a rear perspective view thereof; 
         FIG. 24  is front elevation view thereof; 
         FIG. 25  is a rear elevation view thereof; 
         FIG. 26  is a top plan view thereof, the bottom plan view being the same; and 
         FIG. 27  is a right side elevation view thereof, the left side elevation view being a minor image thereof about any vertical plane extending into the page to the left or right of the image. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
     Referring to  FIGS. 1-8 , while referring generally to  FIG. 1-27 , an apparatus  10  may include a speaker system having a fitting  11  adapting the speaker system  10  to fit within an outer ear channel of a user. In the illustrated embodiment, the fitting  11  may be formed to have flutes  12  acting to apply a force to a wall of the outer ear channel of a user or wearer of the apparatus  10 . 
     In the illustrated embodiments, the flutes  12  of the fitting  11  may include apertures  14  formed in the flutes  12  of the fitting  11  or positioned between adjacent flutes  12 . The apertures  14  provide a bypass region  14  in order that sound may pass through the fitting  11 , past the apparatus  10 , and into the ear of a listener. The apertures  14  thus provide a sound channel  14  for environmental sounds to bypass the apparatus  10 , and reach a user. The apertures  14  thus do tend to pass filtered background sounds a means to bypass the fitting  11 , thus rendering the fitting  11  no longer an ear plug as a sound deadening device. 
     An apparatus  10  provided with a fitting  11  presenting flutes  12  that are formed of a resilient material, such as a rubber, synthetic polymer, or other elastomeric material, provides a compressible fit within the outer ear of a user. Thus, the flutes  12  secure the apparatus  10 , in place, by virtue of the compressibility of the flutes  12  of the fixture  11 . Meanwhile, apertures  14  provided among the flutes  12  provide a bypass channel  14  in order to pass sound through the fitting  11  and apparatus  10  to the outer ear channel of a wearer or user. 
     A channel  16  is formed within a sleeve  18 . The sleeve  18  is typically centrally located from the outer surface of the fitting  11 . Typically, the outer surface of the fitting  11  is the outer surface of the flutes  12  themselves. 
     However, the flutes  12  may be formed in a variety of configurations in order to accomplish their functions. In some embodiments the flutes  12  may actually be constituted by a surface. In other embodiments, the flutes  12  may be narrower or wider and may be rib-like in their shape. Accordingly, such flutes  12  may fold, compress, or the like in order to deflect to fit within the outer ear channel of a wearer. 
     Meanwhile, the sound channel  16  is formed in the sleeve  18 , and the sleeve  18  forms the central element connecting between the speaker  20  of the apparatus  10  and the outer ear channel of a user. 
     For example, the speaker  20  may be enclosed in a housing  22 . The housing may typically be formed of a comparatively rigid or stiff polymeric material, such as a hard plastic. The housing  22  thus provides a degree of protection to the overall speaker system  20  or speaker  20 . 
     By the same token, a stem  24  may form a transition member  24  between the housing  22 , and a cord  26  carrying the electronic signals to the speaker  20 . After conversion by the speaker  20  into audio waves or sound waves, the music or other material can be heard by a user after transmission through the channel  16  into the outer ear channel of the user. 
     The apertures  14  may be sized to have a width and a length of characteristic acoustic distances. The wavelengths that pass through openings are controlled by the dimensions of the openings that will permit those wavelengths to pass. Thus, an aperture  14  operates to a certain degree as a filter for sound. Sound waves that will be passed through air through the apertures  14  must have a wavelength less than the characteristic length defined by an aperture  14 . 
     In operation, each fitting  11  fits into an outer ear channel of a user, and thus may be partially closed. Nevertheless, the clearance or relief provided between the flutes  12  and the sleeve  18 , is bounded. The boundary is defined by the outer ear channel or the wall of the outer ear channel of a user. The flutes and ear wall define the passage opening the apertures  14  provide or enforce. 
     Referring to  FIGS. 7-10 , while continuing to refer generally to  FIGS. 1-27 , the sleeve  18  may fit around a portion of the housing  22  that houses the speaker  20 . A housing  22  may have a shank portion  28 , or a mount  28 , that extends away from the larger portion of the housing  22  in which an actual speaker  20  is contained in the speaker system  20 . Typically, the shank  28  is slightly larger than the internal diameter of the sleeve  18 . Thus, the sleeve  18  may form a friction fit around the shank  28 . This maintains the sleeve  18  and the resulting fitting  11  of the apparatus  10  firmly secured to the shank  28 . In certain embodiments, a relief, detent, or other interference on the shank  28  may interact with a corresponding portion in the side the sleeve  18 . This provides an affirmative grip or securement of the sleeve  18  on the shank  28 . 
     In general, the directions  30  of  FIG. 2 , defining the apparatus  10  and its use with respect to a wearer, may be defined as an axial direction  30   a  that effectively runs parallel to the channel  16  and down the center of the sleeve  18  as well as the center of the shank  28 . This forms the axis along which the audio waves are transmitted from the speaker  20  into the ear of a wearer. 
     Likewise, a lateral direction  30   b  may be thought of as a horizontal direction, nominally, while a transverse direction  30   c  may be thought of as a nominal vertical direction. Nevertheless, both the lateral direction  30   b  and the transverse direction  30   c  are actual radial directions  30   d . A radial direction  30   d  is orthogonal to the axial direction  30   a  but may go in any direction around a full 360 degrees in a plane, any plane, perpendicular to the axial direction  30   a.    
     Accordingly, ribs  32  formed behind the flutes  12 , or as a supporting portion of a flute  12 , or in some embodiments as the structure of the flute  12 , maintain an outer surface against the inner surface of the outer ear channel of a user. 
     For example, in the embodiments of  FIGS. 1-8  and  17 - 27 , the ribs  32  may serve as spacers or supports for the flutes  12 . Thus, the ribs  32  extend between the sleeve  18  and the flutes  12 . Thus, the ribs  12  each provide a column  32  that may apply a force to the flutes  12 , thus urging the flutes  12  to fit snugly against the inside surface of the wall of an outer ear channel of a user. 
     The ribs  32  may be formed of a suitable material, and typically will be homogeneously molded with the sleeve  18  and flutes  12  as a monolithic, integrated, and homogeneous construction. Nevertheless, the apparatus  10  may be assembled, and even the fitting  11  may be assembled. It may be productively manufactured in a molding process as a single integrated piece  11 . 
     Referring to  FIGS. 11-27 , while continuing to refer generally to  FIGS. 1-27 , various alternative embodiments for a fitting  11  of an apparatus  10  may include variations in the size, shape, orientations, positions, and the like of the flutes  12  and their intermediate apertures  14 . 
     Referring to  FIG. 11 , various mechanisms for securement may be provided. In this embodiment of a fitting  11 , a sleeve  18  is centered within the fixture  11 . The flute  12  is shown as an entirely enclosed surface. Nevertheless, the embodiment of  FIG. 11  illustrates a shaping of the interior channel  16  of the sleeve  18  in order to provide easier deflection, and yet a gripping by the sleeve  18  against the shank  28  of a housing  22 . The outer surface or material of the fitting  11  may be perforated with apertures  14  according to any or all of the suitable embodiments illustrated, for example, that of  FIG. 12 . 
     Referring to  FIG. 12 , in one embodiment of an apparatus  10  in accordance with the invention, the flutes  12  are actually simply the material of the fitting  11 . The fitting  11  is, provided with apertures, discretely positioned and separated from one another. Thus, the sleeve  18  and the sound channel  16  through the fitting  11  operate in accordance with the other embodiments illustrated herein. 
     Referring to  FIGS. 13-14 , the flutes  12  may be spaced a substantial distance apart. For example, the illustrated embodiments of  FIGS. 13-14  show alternative mechanisms for supporting the flutes  12  spaced away from the sleeve  18 . In the embodiment of  FIG. 13 , no ribs  32  are shown. 
     However, in the embodiment of  FIG. 14 , ribs  32  space the flutes  12  a distance away from the sleeve  18 . The ribs  32  each form a support member  32  that may flexibly urge each of the corresponding flutes  12  into contact against the surface of an outer ear channel of a wearer. 
     Referring to  FIGS. 15-16 , flutes  12  may be separated from one another, and each may emanate, by extending in a radial direction  30   d , away from the center sleeve  18 . In the illustrated embodiment, the convergence of the individual flutes  12  actually forms the central sleeve  18 . The sleeve  18  then may or may not be discretely identifiable separate from the flutes  12 , as the sleeve  18  defines the sound channel  16 . 
     Referring to  FIG. 16 , the flutes  12  in one embodiment may be serrated along their edges in order to provide a more gripping surface. For example, by having a serrated edge on one or more of the flutes  12 , areas of higher and lower pressure alternate. Thus, the tendency is for a greater resistence to sliding. That is, each area of higher compression corresponds to an area of a higher tooth on the serrated edge of a flute  12 . In this manner, the tooth has a larger incursion in depressing the outer ear channel wall against which it fits, leaving less depression in the areas or valleys between the teeth (or crests) of the serrations. Thus, greater support against axial movement may be achieved. 
     Referring to  FIG. 17 , the embodiment of  FIG. 17  may or may not include ribs  32  as illustrated in  FIGS. 1-8 . In this embodiment, as in the embodiment of  FIG. 13 , a stiffer material may not benefit as much from the presence of ribs  32 . Likewise, manufacturing may be somewhat simpler. Nevertheless, a substantially softer material, even a foamed elastomeric material, may be used to mold many of the embodiments of fittings  11 , thereby providing sufficient flexibility for comfort. Meanwhile, ribs  32  may act as stiffeners. A rib  32  provides additional radial force. Ribs  32  act as supports, stabilizers, or the like in order to maintain the distance, spacing, or he like. Ribs  32  enforce, under pressure, the original tendency of flutes to stay spaced apart from the sleeve  18  and from the other flutes  12 . 
     Referring to  FIGS. 18-27 , while continuing to refer generally to  FIGS. 1-27 , a fitting  11  may take on various configurations suitable to the material selected and the comfort of a user. For example, radial supports, such as ribs  32 , may apply force in a radially outward direction against a flute  12 , on the outside. They may apply corresponding force against the sleeve  18  located on the inside thereof Likewise, circumferential support may be provided by and actually may deflect the flutes. 
     Referring to  FIG. 18 , for example, the flutes  12  extend circumferentially around the sleeve  18 , spaced away from the sleeve  18  by the ribs  32 . Meanwhile, the flutes  12  have a convoluted shape that varies in diameter and radius as the flutes progress along the axial direction  30   a . Thus, one or more ribs  32 , which may or may not be continual in the axial direction, space the sleeve  18  from the flutes  12 , and represent a somewhat convoluted outer surface. Thus, in this embodiment, as in the embodiment of  FIG. 16 , alternating areas of higher pressure and lower pressure tend to provide additional gripping against axial dislodgement of the apparatus  10 . 
     Referring to  FIG. 19 , an embodiment having no outer rim for the flutes  12 , but simply the flutes  12  themselves, are effectively like ribs  32 . They extend from the sleeve  18  and contact directly the surface of the outer ear channel of the wearer. In this embodiment, the edge of each flute  12  itself may fit against the ear channel of a user, and maintain the sleeve  18  against dislodgement. In this embodiment, a stiffer material may be needed than in certain of the other embodiments, where more surface area, more material, and more contact area are provided. 
     However, in this embodiment, the aperture region  14  is substantial, and effectually is most of the projected area of the entire fitting  11 . That is, for example, proceeding in an axial direction  30   a , the majority of the cross-sectional area circumscribed by the envelope around the fitting  11  is the aperture region  14  itself. Only the four flutes  12 , which could be three flutes  12  in certain embodiments, or another number, actually represent spacing and structure between the sleeve  18  and the wall of the outer ear channel. 
     Referring to  FIG. 20 , in one embodiment, as illustrated in  FIG. 19 , the flutes  12  may compress, deflect, or otherwise change shape in order to fit within the ear channel of a user. In the illustrated embodiment, two of the flutes  12  maintain substantially their shape, while two others are deflected or distorted in order to fit in the ear channel of the wearer. 
     Referring to  FIG. 21 , similarly, the embodiment of  FIG. 18  shows the flutes  12  that basically rely on the rim  34  around the ribs  32 . All may deflect selectively in order to fit within the outer ear channel of a user. Thus, a rim  34  may be desirable to maintain a certain amount of stability between the ribs  32  that together with the rim  34  actually form the flutes  12  or the structure  12  that axial flutes  12  would otherwise provide. 
     Referring to  FIGS. 22-27 , while continuing to refer generally to  FIGS. 1-27 , a speaker system  10  may be provided with a fitting  11  (i.e., interface) suitable for interfacing between an outer ear canal of a user and the speaker system  20  of an audio device. In the illustrated embodiment, the rim  34  is noticeably absent between the adjacent ribs  32  and flutes  12 . In this embodiment, it has been found effective to provide a fitting  11  having flutes  12  surrounding the sleeve  18 . Each flute  12  is supported by a rib  32  extending radially between the sleeve  18  and the corresponding flute  12 . 
     The material of which the fitting  11  is molded or cast may be any suitable material, but an elastomeric polymer material has been found most suitable. For example, silicone compounds have been found suitable, and sufficiently durable. Meanwhile, they have sufficient softness (e.g., by durometer test value) and flexibility (e.g., by mechanical stiffness and deflection underload) to match mechanical properties of, fit well into, the outer ear canal of a user in the dimensions illustrated. 
     In other embodiments in which a rim  34  interconnects the ribs  32  or flutes  12  of the fitting  11 , a conservation-of-mass principle as well as the mechanical stiffness of the rim  34  and rib  32  combination tends to stabilize the flutes  12  more than necessary. Inasmuch as the shape of the flutes  12  is fitted to contact the surface of the skin lining the outer ear canal of a user, the flutes  12  tend to stabilize within the ear channel. 
     Meanwhile, deflections as required may occur in the flutes  12 . Of particular note, the ribs  32  are made to have a thickness and height (height measured radially from the sleeve  18 ) to be sufficiently flexible to engage in column buckling. To the extent that the fitting  11  needs to deform or deflect to fit inside the outer ear canal, that deflection may be provided by buckling of one or more of the ribs  32 . By buckling, the ribs  32  necessarily displace into the channels  14  between the ribs  32 . Nevertheless, to the extent that a rib  32  occludes part of a channel  14 , it will tend to open up the adjacent channel  14  on the opposite side of the rib  32 . 
     In the illustrated embodiment, it has been found that comfort, fit, and ease of application are all well served by the fitting  11  made in accordance with the illustrated embodiment, and lacking any rim  34  interconnecting the flutes  12 . One may form the ribs  32  to be of any suitable thickness and height, depending on comfort for the wearer. That is, for example, the thickness of the ribs  32  will influence the effective pressure exerted by the ribs  32  on the flutes  12 . The flutes  12 , in turn, exert pressure against the skin of a user. 
     It has been found effective to make the fitting  11  in the dimensional relationships illustrated, of a silicone material in three different sizes. A larger diameter size is for adults having a larger outer ear channel, the medium size is for other adults, and the smaller size is for children and those adults having a comparatively narrower ear channel. The safety passages  14  carry environmental sound into the outer ear channel improving safety of a wearer. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.