Abstract:
Among other things, an ear tip for an earpiece is described. The ear tip comprises a body and two flexible flaps extending from the body. The two flexible flaps together form a generally frustro-conical shape around the body and at least part of the body is partially enclosed by the two flexible flaps.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure generally relates to earpieces for use with electronic devices, which may include one or more flexible flaps. 
       BACKGROUND 
       [0002]    Earpieces can be placed within human ears, e.g., as part of earphones, Bluetooth devices, etc., to deliver sound to the ears. To enhance sound quality and the user&#39;s acoustic experience, earpieces may be configured to enhance passive noise attenuation. For example, an earpiece may substantially seal the entrance of a user&#39;s ear canal so that sound delivered to the ear does not leak to the external environment, and so other sounds, e.g., the passive noise, from the environment, are substantially blocked. In another example, an earpiece may have an incomplete seal to allow for situational awareness. The earpiece may provide a desired level of acoustic leak. 
       SUMMARY 
       [0003]    In one aspect, the disclosure features an ear tip for an earpiece. The ear tip comprises a body and two flexible flaps extending from the body. The two flexible flaps together form a generally frustro-conical shape around the body and at least part of the body is partially enclosed by the two flexible flaps. 
         [0004]    In another aspect, the disclosure features an ear tip comprising a body, a positioning and retaining structure, and two or more flaps extending from and connected to the body. The two or more flaps form a frusto-conical shape. The positioning and retaining structure includes a member extending from the body and configured to rest against and apply outward pressure to the antihelix of a user&#39;s ear to retain the ear tip in the user&#39;s ear. 
         [0005]    In another aspect, the disclosure features an ear tip for an earpiece. The ear tip comprises a body and two compliant flaps together forming a frusto-conical structure surrounding the body. At least part of the body is partially enclosed by the frusto-conical structure. The two flaps each has an inner perimeter connected to the body and an outer perimeter away from the body. The two flaps also each comprises two ends each extending between the inner perimeter and the outer perimeter. At least two ends of the two flaps overlap along a peripheral direction of the inner or outer perimeters in an overlapping region. 
         [0006]    In another aspect, the disclosure features an earpiece comprising a body defining an opening as an acoustic passage to conduct sound waves, two flaps connected to the body, and an acoustic driver configured to radiate sound waves to be conducted through the acoustic passage. Each flap is flexible in response to applied force so as to enclose at least part of the body. 
         [0007]    Embodiments of the ear tips and earpieces may include one or more of the following features. A first flap of the two flaps is smaller in size than a second flap of the two flaps. The body comprises a front part and a back part, and the first flap is connected to the body at a location such that when the ear tip is held in a human ear with the front part of the body positioned at the entrance to the ear canal, the first flap is on an inner side of the tragus of the human ear. The first flap has the shape of a portion of a first oval and has a size smaller than half of the first oval. The second flap has the shape of a portion of a second oval and has a size larger than half of the second oval. A first flap of the two flaps is connected to the body at a first inner perimeter, and has a first outer perimeter and first and second ends extending between the first inner perimeter and the first outer perimeter. A second flap of the two flaps is connected to the body at a second inner perimeter, and has a second outer perimeter and third and fourth ends extending between the second inner perimeter and the second outer perimeter. The first end overlaps with the third end along the first and second inner perimeter, and the second end overlaps with the fourth end along the first and second inner perimeter. The first and third ends are separated by a gap having a width of about 0 mm to about 1 mm at the first and second perimeters. The first and third ends are separated by a gap having a width of about 0.1 mm to about 1.6 mm at the first and second outer perimeters. Each flap has a thickness of about 0.15 mm to about 1.5 mm. The body comprises a front part and a back part, and the back part of the body comprises a surface having a first region having a round shape and one or more second, flat regions under the one or more flaps. The flaps are configured to bend towards the body so that the ends in the overlapping region slide towards each other along the peripheral direction to increase an amount of the overlap. The ear tip comprises three or more flaps. The two flaps comprise silicone. There are exactly two flaps. A first flap of the two flaps is smaller in size than a second flap of the two flaps. The two flaps each have an inner perimeter connected to the body and an outer perimeter away from the body, the flaps also each have two ends each extending between the inner perimeter and the outer perimeter, and at least two ends of the flaps overlap along a peripheral direction of the inner or outer perimeters in an overlapping region. The earpiece comprises three or more flaps that mutually engage to form a conical structure. The frusto-conical shape has an aperture angle of about 30 degrees to about 90 degrees. The ear tip comprises at least two flaps having ends overlap in an overlapping region. The positioning and retaining structure forms a consistent leak of sound external to the human ear to the human ear in the overlapping region. 
         [0008]    Two or more of the features described in this disclosure, including those described in this summary section, may be combined to form implementations not specifically described herein. 
         [0009]    The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1A  is a schematic view of a lateral surface of a human ear. 
           [0011]      FIGS. 1B and 1C  are schematic cross-sectional views of human ears. 
           [0012]      FIG. 2  is an isometric view of an example earpiece. 
           [0013]      FIG. 2A  is an isometric view of an example tip of an earpiece. 
           [0014]      FIG. 2B  is a schematic view of a frusto-conical structure. 
           [0015]      FIGS. 2C and 2D  are top views of example petal flaps. 
           [0016]      FIGS. 2E and 2F  are mechanical drawings of example petal flaps. 
           [0017]      FIG. 2G  is a top view of a frusto-conical structure formed by example petal flaps. 
           [0018]      FIGS. 2H ,  2 I,  2 J, and  2 K are schematic perspective views of parts of example tips of earpieces. 
           [0019]      FIG. 3  is a schematic lateral view of an example ear piece in a human ear. 
           [0020]      FIG. 4A  is a schematic view of a frusto-conical structure. 
           [0021]      FIGS. 4B and 4C  are schematic top views of inner perimeters of multiple flaps. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    An example earpiece includes a tip that can fit ears of different users having a range of sizes and geometries. The tip can also seal to the ears of different users, thereby enhancing user-experienced sound quality. The tip may include one or more petal flaps surrounding a body of the tip. The flap(s) can form a frusto-conical shape, which has a bottom having an oval shape. The flap(s) can also have other shapes, e.g., a bulb shape. The flap(s) can be a continuous piece of material having at least one break along the generatrix of the cone and two ends along a peripheral direction of the bottom of the frusto-conical shape. Each end may extend between a top and the bottom of the frusto-conical shape. In some implementations, two or more petal flaps having the same or different dimensions are arranged along the circumference of the tip body and in combination form the frusto-conical shape. The ends of the flap(s) can overlap along the peripheral direction. 
         [0023]    The flap(s) can allow the tip to be inserted flexibly at different depths of the ear canals to provide an acoustic seal or acoustic coupling to the ear. In some implementations, the acoustic seal is a passive noise seal. In some implementations, the flap(s) can provide a given consistent leak into the ear canal, e.g., by tuning parameters associated with the flap(s), e.g., flap thickness(es) and air gap molded in between ends of the flap(s). The details of these parameters are discussed further below. The flaps can be configured to seal to a user&#39;s ear at the entrance of the ear canal to create a consistent coupling to the user&#39;s ear canal. The flap(s) can conform to the irregular geometry of a user&#39;s ear canal entrance by compressing outer perimeter(s) of the flaps and increasing the overlap between the ends at the outer perimeter(s). The seal to the user&#39;s ear can be formed farther out along the user&#39;s ear canal than the seal formed by a tip without the flap(s). As some users have ear canals that are sensitive, placing the tip farther out, near the entrance of the ear canal, can result in a more comfortable fit. In addition, a tip having the flap(s) can fit differently sized ears more easily than a tip without such flap(s). When adjusted along the major axis of an ear canal, the flap(s) can change their shapes to conform to the unique ear geometry and change length(s) of the outer perimeter(s). For example, the flap(s) can flexibly provide a large initial frusto-conical geometry, in which the petals are uncompressed or slightly compressed to accommodate large ears. The flap(s) can also be compressed to fit smaller ears when the ends of the flap(s) slide past one another, reducing the effective cone size. 
         [0024]    In the example implementations described herein, the left and right earpieces mirror each other, but have the same structure and function. Features of the right earpiece are described below. The left earpiece has the same features in this example implementation. 
         [0025]      FIG. 1A  shows the lateral surface of a human right ear  10 , with features of the ear identified. However, different ears have different sizes and geometries. In this regard, the precise structure of the human ear varies from individual to individual. For example, some ears have additional features that are not shown in  FIG. 1A , and some ears may lack some of the features that are shown in  FIG. 1A . Likewise, some features of different ears may be more or less prominent than those shown in  FIG. 1A . 
         [0026]      FIGS. 1B and 1C  show two cross-sections of the human ears  12 ,  14 . In these examples, the ear canal is an irregularly shaped cylinder having a variable cross-sectional area and a center line that is not straight. Among the features identified in the figures are the entrance to the ear canal and the main portion of the ear canal. In the example, the entrance to the ear canal corresponds to the portion of the ear canal near the concha, where the walls of the ear canal are substantially non parallel to the center line of the ear canal. In contrast to the ear of  FIG. 1C , the ear of  FIG. 1B  has a relatively sharp transition from ear canal walls that are non-parallel to a center line  30 - 1 B of the ear canal to walls that are substantially parallel to a center line of the ear canal. The ear shown in  FIG. 1C  has a more gradual transition from walls that are non-parallel to a centerline  30 - 1 C of the ear canal to walls that are substantially parallel to the centerline  30 - 1 C of the ear canal. The entrance  32 - 1 C to the ear canal is relatively long compared to the entrance  32 - 1 B. 
         [0027]      FIG. 2  shows an example earpiece  20  that is configured to fit in ears  10 ,  12 ,  14  of  FIGS. 1A-1C . The earpiece  20  includes a stem  52  for positioning cabling and the like to receive audio signals to be delivered to an ear, an acoustic driver module  26 , and a tip  60 , which is also shown in  FIG. 2A . Some earpieces may lack the stem  52 , but may include an electronics module (not shown) for wirelessly communicating with external devices. Some ear pieces may include the driver and acoustics but lack stem  52  and electronics module. Other earpieces may lack the stem and the acoustic driver module and may function as passive earplugs. In this context, a passive earplug includes an earplug that does not include acoustic features, i.e., they do not provide sound to the ear. 
         [0028]      FIG. 2A  shows an example tip of the earpiece of  FIG. 2 . The tip  60  includes a positioning and retaining structure  28  connected to a sealing structure  48 . The positioning and retaining structure  28  includes an outer leg  22  and an inner leg  24  that are joined to the sealing structure  48  at one end  30  and that are joined to each other at the other end  32 . The sealing structure includes a body  34  and two petal flaps  38 ,  40  forming a frusto-conical structure  36 . The body  34  includes a back part  42  that is at least partially covered by, or under, the frusto-conical structure  36 , and a front part  44  that extends beyond the frusto-conical structure  36 . The body  34  defines an opening  46  extending from the back part  42  to the front part  44 . In the back part  42 , the acoustic driver module  26  and the stem  52  can mount to the opening  46 . In the front part, sound waves can be delivered through the opening to an ear. Although not shown in the figures, in some implementations, the entire body  34 , including the front and the back parts  44 ,  42 , is covered, or under, the frusto-conical structure. Sometimes part of the body  34 , e.g., the front part  44 , is also called a nozzle. 
         [0029]      FIG. 2B  shows an example frusto-conical structure  36  that is formed from the combination of two petal flaps  38 ,  40 . The bottom  80  of the structure  36  has an oval- or elliptical-like shape. The perimeter of the bottom  80  corresponds to the outer perimeters of the two flaps  38 ,  40 . The top  82  of the structure  36  has a shape that corresponds to the cross-sectional shape of the front part  44  of the body  34 . For example, the shape can be substantially oval, elliptical, or circular. The perimeter of the top  82  corresponds to the inner perimeters of the two flaps  38 ,  40 , at which the flaps connect to the body  34 . The cone surface  84  between the top  82  and the bottom  80  corresponds to outer surfaces of the flaps  38 ,  40  that face an ear wall when the tip  60  is placed in an ear. As is shown in the figure, neither of the bottom  80  nor the top  82  has a perfect oval elliptical or circular shape. This is because there is a gap  86  between the two flaps and the ends of the flaps overlap along a peripheral direction  88 . Accordingly, the outer surfaces of the flaps do not form a continuous surface. The details of the gap and the overlapping are discussed further below. 
         [0030]      FIGS. 2C and 2D  show top views of example petal flaps that form the frusto-conical structure  36  of  FIGS. 2A and 2B . In some implementations, the two flaps  38 ,  40  have different shapes and sizes. Referring in particular to  FIGS. 2 and 2C , the petal flap  38  generally can be viewed as a portion of a shape  90 . The flap  38  has an inner perimeter  92  that is part of a small inner oval  96 , and has an outer perimeter  94  that is part of a large outer oval  98 . The inner perimeter  92  connects to the body  34  of the tip  60 . In some implementations, the petal flap  38  is less than half of the total size of the shape  90  and is symmetric relative to a short axis  104  of the inner oval  96  or a short axis  102  of the outer oval  98 . The part of the inner oval  96  forming the inner perimeter  92  corresponds to a central angle α from a center  100  of the inner oval  96 . In some implementations, the angle α may also correspond to an angle between flap edges  112 ,  116 . In some implementations, the angle α is smaller than 180 degrees, e.g., about 95 degrees to about 175 degrees, or about 157.5 degrees. The part of the outer oval  98  forming the outer perimeter  94  may correspond to the same central angle α or a different central angle of the outer oval  98 . 
         [0031]    Referring to  FIGS. 2 and 2D , the petal flap  40  can also be generally viewed as a portion of a shape  120  that has an inner perimeter  126  that forms part of an inner small ellipse  122  and an outer perimeter  128  that forms part of an outer large ellipse  124 . The inner and outer ellipses are shown for explanation, and are not actually part of the earpieces in this example implementation. The inner perimeter  126  connects to the body  34  of the tip  60 . In some implementations, the large ellipse  124  has a major radius of about 7 mm to about 15 mm, e.g., about 10.75 mm and a minor radius of about 4 mm to about 10 mm, e.g., about 6.75 mm. In some implementations, the small ellipse  122  has a major radius of about 2 mm to about 7 mm, e.g., about 4.65 mm and a minor radius of about 1 mm to about 6 mm, e.g., about 3.75 mm. 
         [0032]    In some implementations, the petal flap  40  is more than half of the total size of the shape  120  and is symmetric relative to the short axis  130 ,  132  of the inner ellipse  122  or the outer ellipse  124 . Compared to the shape  120 , the flap  40  misses a portion that corresponds to a gap  134 , e.g., a fan shaped gap, in the shape  120 . In some implementations, the gap  134  has inner perimeter  136  corresponding to a central angle β of less than 180 degrees, e.g., about 55 degrees to about 150 degrees or about 85 degrees. The outer perimeter  138  of the gap  134  may correspond to the same central angle β or a different angle. 
         [0033]    Referring to  FIG. 2I , in some implementations, each petal flap  38 ,  40  has a thickness  150 ,  152  of about 0.15 mm to about 1.5 mm, e.g., about 0.5 mm. The two flaps can have the same thickness or different thicknesses. An inner surface  154  and an outer surface  156  of the flap  38  can connect at the outer perimeter  94  of the flap  38  through a curved surface, e.g., with a blend radius R b  of about 0.5 mm. The curved surface can provide a smooth touch to the outer perimeter  94 . Similarly, the outer perimeter  128  of the flap  40  can also be smooth. 
         [0034]    The actual sizes and shapes of the petal flaps  38 ,  40  can vary based on various factors including, but not limited to, the sizes of user ears, earpiece material properties, e.g., hardness, of the flaps, the manufacturing processes, e.g., the ease of manufacturing, etc. For example, differently sized petal flaps can be used for different groups of users having different ear sizes. The actual sizes of an example set of petal flaps  38 ,  40  are shown in the mechanical drawings of  FIGS. 2E and 2F , respectively. The dimensions in the drawings are in millimeters, unless otherwise specified. 
         [0035]    Referring to the examples of  FIGS. 2G ,  2 H, and  2 I, the petal flaps  38 ,  40  on the body  34  of the tip  60  overlap along the peripheral direction  160  at both end regions  164 ,  166  of the two flaps. For example, a portion  162  of the inner perimeter  126  of the flap  40  overlaps with the flap  38  by an amount that corresponds to a central angle γ at a center  168  of the inner perimeter  126 . Another portion  170  of the inner perimeter  126  of the flap  40  overlaps with the flap  38  by an amount that corresponds to a central angles θ at the center  168 . In some implementations, the angles γ, θ can be the same or can be different and are in the range of about 10 degrees to about 60 degrees, e.g., about 30 degrees to about 40 degrees, or about 36 degrees. 
         [0036]    In this example implementation, the inner perimeters  92 ,  126  of the flaps  38 ,  40  are connected to the body  34  to form the top of the frusto-conical structure  36  that surrounds the body  34 . The front part  44  of the body  34  extends beyond the frusto-conical structure  36  through an opening  180  defined by the perimeters  92 ,  126 . Referring again to  FIG. 2I , in some implementations, a bottom gap  182  formed between the two flaps  38 ,  40  on the body  34  has a width of about 0 mm to about 1 mm, e.g., about 0.35 mm. In some implementations, the outer perimeters  94 ,  128  of the flaps  38 ,  40  form a top gap having a width of about 0.1 mm to about 1.6 mm, e.g., about 0.8 mm. 
         [0037]    In the example shown in  FIGS. 2G-2I , the flap  38  is arranged in front of the flap  40  such that in the overlapping regions  164 ,  166 , the outer surface  156  of the flap  38  is closer to a front end of the front part  44  than the outer surface of the flap  44 . The flaps  38 ,  40  can also be arranged in a reverse sequence in which the flap  40  is arranged in front of the flap  38 . The location of the flap  38  on the body  34  is chosen such that when the tip  60  is placed and secured in an ear, the flap  38  is on the inner side of the tragus of the ear (see, e.g.,  FIG. 1A ). The relatively small size of the flap  38  can allow the flap to flexibly conform to the tragus shapes of different ears. For some users, this configuration may provide for a more comfortable fit and a more consistent seal to the ear. 
         [0038]    For some users, the overlap between the two flaps in the end regions  164 ,  166  can also provide seal to an ear to reduce an amount of passive noise entering the ear canal. When the outer surfaces of the flaps  38 ,  40  are compressed against the ear wall, the flaps can bend towards the body  34  such that a size of the bottom  80  (see, e.g.,  FIG. 2B ) of the frusto-conical structure  36  is reduced. During compression, the inner perimeters  92 ,  126  of the flaps remain stationary relative to the body  34  of the tip  60 , while the outer perimeters  94 ,  128  slide towards each other within regions  164 ,  166 . As a result, along the outer perimeters, the flaps  38 ,  40  overlap more than when they are uncompressed. For some users, the increased overlap further may seal the entry to the ear without the tip being deep into the ear canal. 
         [0039]    In some implementations, when the main angle of a cone formed by one or more flaps becomes large, i.e., when the cone begins to look more like a disk, the tip  60  may no longer be able to properly locate itself in the ear as its proper position becomes ambiguous. In some examples, the front part  44  of the tip  60  engages the ear canal entrance beyond the sealing location of the flap portions when the tip is properly positioned in the user&#39;s ear. The nozzle can extend past the connection of flaps  40  and  38  with the body  34  and directly engage some portions of a user ear canal. This nozzle can increase the ability of the tip to be properly positioned in the ear and can allow the tip to achieve greater stability. The nozzle is sized so that it is smaller than typical ear canal opening, such that it does not create a static force on the ear canal wall. Rather, the tip is used as a locating feature during installation to help reduce fit ambiguity, which may occur when there is no such nozzle. In some implementations, the nozzle has a profile that is in the shape of an ellipse. The ellipse can have a major axis radius that ranges from about 1 mm to about 5 mm, e.g., about 3.25 mm, and a minor axis radius that ranges from about 0.5 mm to about 3 mm, e.g., about 1.25 mm. In some implementations, the nozzle can have a length that ranges from about 1 mm to about 8 mm, e.g., about 4.25 mm. 
         [0040]    In some implementations (e.g.,  FIGS. 2A and 2I ), to facilitate bending of the flaps  38 ,  40  towards the body  34 , the generally round outer surface of the back part  42  of the body  34  is modified in regions  220 ,  222  under the flaps  40 ,  38 . For example, in the regions  220 ,  222 , body materials are removed to form flat surfaces so that the flaps  40 ,  38  can bend towards the regions  220 ,  222  without the body materials substantially obstructing the bending. 
         [0041]    The flaps can bend by any appropriate amount. The flexibility of the flaps during compression can also allow the tip to consistently fit ears of different sizes and geometries, thereby reducing the need to customize the configuration of the tip for each user. The amount of compression and increased overlap needed or experienced by different users may be different. 
         [0042]    The locations and orientations of the flaps  38 ,  40  relative to the front part  44  of the body  34  can be chosen based on different factors, including for example, manufacturing processes or sizes and geometries of user ears. In some implementations, the tip  60  can be manufactured in several (e.g., three) different sizes, one for a group of users who have relatively small ears, e.g., children, one for a group of users who have medium-sized ears, e.g., a majority of adults, and one for a group of users who have large sized ears. In addition to the arrangement of the flaps  38 ,  40 , as described herein, the sizes and shapes of the flaps can be different for differently shaped tips. 
         [0043]      FIG. 2H  shows a perspective side view of a part of the tip  60  in a plane. For the purpose of describing example sizes of the part shown in the figure, five lines A-E in the same plane are defined as follows: 
         [0044]    Line A is in a plane substantially parallel to the concha plane, which can be substantially parallel to the sagittal plane. Line B is in a plane tangent to the front surface of the petal  40 . Line C is in a plane tangent to the front surface of the nozzle  44 . Line D is in a plane tangent to the outer perimeter  128  of the petal  40 . Line E is in a plane tangent to the front surface of the petal  38 . 
         [0045]    In some implementations, the lines B and E, or the front surfaces of the petals  38 ,  40  form an angle of about 60° to about 180°, e.g., about 116.76° as shown in the figure as an example. This angle defines the angle of the top conical section formed by the petals and locates the petals relative to each other in this view. In some implementations, the lines A and B, or the front surface of the petal  40  and the line A, form an angle of about −30° to about 60°, e.g., about 15.38° as shown in the figure as an example. This angle locates the two petals  38 ,  40  on the body  34 . In some implementations, the lines A and D, or the outer perimeter  128  of the petal  40  and the line  40 , form an angle of about 10° to about 85°, e.g., about 48.00° in the figure as an example. In some implementations, the height of the frusto-conical structure  36  is about 1 mm to about 8 mm, e.g., about 4.66 mm as shown in the figure as an example. The height can be defined as a distance from the rearmost point on the petal  40  to the front most point on the petal  38 . This distance can be measured along a line that is normal to line D or to a plane parallel to the back surface of the petal  40 . In some implementations, the lines A and C, or the nozzle face and the line A, form an angle of about −20° to about 60°, e.g., about 13.00° as shown in the figure as an example.  FIG. 2K  shows a perspective view of a part of the tip  60  in the sagittal plane. For the purpose of describing example sizes of the part shown in the figure, three lines F-H in the same sagittal plane are defined as follows: 
         [0046]    Line F is in a plane that is substantially parallel to the plane of  FIG. 2H . Line G is in a plane tangent to the front surface of the petal  38 . Line H is in a plane tangent to the outer perimeter  128  of the petal  40 . 
         [0047]    In some implementations, the side angle of the conical section formed by the petals  38 ,  40  is about 60° to about 180°, e.g., about 141.05° as shown in the figure as an example. The side angle locates the petals  38 ,  40  relative to each other in this view. In some implementations, the lines F and G, or the conical surface defined by the petals and the line F, form an angle of about 45° to about 150°, e.g., about 109.00°. This angle defines the pitch of the petals  38 ,  40  on the body  34 . In some implementations, the lines F and H, or the outer perimeter  128  of the petal  40  and the line  40 , form an angle of about 45° to about 135°, e.g., about 90.00°. Similar to the view shown in  FIG. 2H , in the sagittal plane, the height of the frusto-conical structure  36  is about 1 mm to about 8 mm, e.g., about 4.66 mm. 
         [0048]    In other implementations, lines or planes other than those shown in  FIGS. 2H and 2K  can be defined or used in determining the different sizes of the tip  60 . 
         [0049]    The shapes and the sizes of the flaps  38 ,  40  and the frusto-conical structure  36  can vary while still providing various advantages for various users. For example, referring to  FIG. 2J , the flaps  38 ,  40  may not have a smooth surface that follows the shape of a cone. Instead the flaps may have flat regions, such as a region  230  of the flap  40 , connected with other regions through corners, such as a corner  232  of the flap  40 . 
         [0050]    The overlapping region(s) between ends of one or more flaps can have different features to provide different degrees of seal to the ear. For example, as described previously, the overlapping region can allow the ear to be fully sealed. When inserted in a user&#39;s ear, the ends of the flap(s) have very little to no gap in the overlapping region. Furthermore, the thickness of the flap(s) can taper down from the inner perimeter to the outer perimeter to be very thin so that the compressed flap(s) create little to no air gap at the sealing location. In some implementations, the overlapping regions can provide consistent leak paths to the ear canal. In this example, the flap thickness may increase from the inner perimeter to the outer perimeter and the gap between flaps is chosen to be larger than the gap used in a tip for providing complete seals. Along the circumference of the tip, the transition from one end of a flap to another end of flap or another end of a different flap is relatively abrupt so that there is a leak path formed between the flaps or between the flaps and the user&#39;s ear canal entrance. 
         [0051]    Referring again to  FIG. 2A , the tip  60  can be manufactured by molding. In some implementations, all parts of the tip  60 , including the sealing structure  48  and the positioning and retaining structure  28 , can be formed integrally. In some implementations, the sealing structure  48  including the body  34  and the flaps  38 ,  40  can be formed integrally through molding using a suitable material including silicone in 8 to 70 Shore A durometer, e.g., 12, 16, or 20 durometer. Other suitable materials can include TPEs, urethanes, or other rubber-type materials. The positioning and retaining structure  28  may be formed integrally through molding. The positioning and retaining structure  28  may then be connected to the sealing structure  48 . In some implementations, the tip  60  can be manufactured in a double injection molding process that molds an insert piece with a hard durometer material first and then molds a soft durometer material around the insert piece. In some implementations, the tip  60  can be coated with an anti-dust coating. Example coating materials is described in U.S. Pat. No. 8,600,096, the entire content of which is incorporated herein by reference. 
         [0052]    Although two petal flaps are described with respect to FIGS.  2  and  2 A- 2 J, a tip can also include a different number of petal flaps. For example, referring to  FIG. 4A , in some implementations, a tip can include a single flap  400  that has a general frusto-conical shape similar to the structure shown in  FIG. 2B . The flap  400  may include a break  402  formed by two ends  404 ,  406  that overlap along a peripheral direction  410  in an overlapping region  408 . The flap  400  can be connected to a body of the tip at an inner perimeter  412 . The overlapping region  408  can have structures and functions similar to those of the overlapping regions of the flaps  38 ,  40  described elsewhere herein. 
         [0053]    In other examples, more than two, e.g., three, four, five, or more, petal flaps can be used in a single earpiece. For example,  FIG. 4B  shows the top view of the inner perimeters  420 ,  422 ,  424  of three flaps  426 ,  428 ,  430 . The edges of the flaps along the peripheral direction  432  overlap in regions  434 ,  436 , and  438 , which can have features and perform functions similar to those of the overlapping regions of the flaps  38 ,  40  described herein.  FIG. 4C  shows the top view of the inner perimeters  450 ,  452 ,  454 ,  456  of four flaps. The edges of the flaps along the peripheral direction  460  overlap in overlapping regions  462 ,  464 ,  466 ,  468 , which can have features and can perform functions similar to those of the overlapping regions of the flaps  38 ,  40  described herein. 
         [0054]    In use, the earpiece  20  of  FIG. 2  is inserted into an ear, such as the ear  10 ,  12 ,  14 , by moving the front part  44  of the sealing structure  48  towards the entrance of the ear canal. As described herein, in response to force produced upon compression against the ear canal, the geometry of the frusto-conical structure  36  changes. The petal flaps  38 ,  40  may also slide relative to each other to adapt to the geometry of the ear or ear canal and to seal the ear canal. The earpiece  20  can be oriented and held in place in a sealing position using the positioning and retaining structure  28  and other portions of the earpiece. 
         [0055]    An example process in which an earpiece is placed and held in an ear is explained in connection with  FIG. 3 . The earpiece  20  of  FIG. 2  is placed in a right ear  70  and pushed inward. The earpiece can be rotated counter-clockwise as indicated by an arrow  41 . Pushing the tip  60  of the earpiece  20  into the ear generates forces that cause the outer leg  22  of the positioning and retaining structure  28  to move into position underneath the anti-helix of the ear  70 . The pushing also generates forces that cause the front part  44  of the sealing structure  48  to enter the ear canal by a small amount (not shown), depending on the dimensions and geometry of the entrance to the ear canal. 
         [0056]    The earpiece  20  is then rotated clockwise as indicated by arrow  41  until one or more conditions occur so that the earpiece cannot be further rotated. The conditions can include, e.g.: an extremity  72  of the tip contacting the base of the helix; the inner leg  24  contacting the base of the helix; or the extremity  72  becoming wedged behind the anti-helix in the cymba concha region. Though the positioning and retaining structure provides all three conditions (hereinafter referred to as “modes)”, not all three conditions will or need to occur for all users, but at least one of the modes will occur for most users. Which condition(s) occur(s) is dependent on the size and geometry of the user&#39;s ears. 
         [0057]    Rotating the earpiece clockwise can cause the extremity  72  and the outer leg  22  to engage the cymba concha region and seat beneath the anti-helix of the ear  70 . When the tip and the positioning and retaining structure  28  are in place, the positioning and retaining structure and/or body contact the ear of most people in at least two, and in some people more, of several ways: a length  74  of the outer leg  22  contacts the anti-helix at the rear of the concha; the extremity  72  of the positioning and retaining structure  28  is underneath the anti-helix; portions of the outer leg  22  or the tip  60  or both are underneath the anti-tragus; and the tip  60  contacts at the entrance to the ear canal under the tragus. The two or more points of contact hold the earpiece in position for many users, providing greater stability for such users. The distribution of force, and the compliance of the portions of the body and the outer leg that contact the ear may lessen pressure on the ear and result in a more comfortable fit. 
         [0058]    It may be desirable to place the earpiece in the ear so that it is oriented properly, so that it is stable (that is, stays in the ear), so that it is comfortable, and, for some applications so that it provides significant passive attenuation of ambient noise. One way of providing stability and proper orientation is described above and is described more completely in U.S. patent application Ser. No. 12/860,531, incorporated herein by reference. 
         [0059]    Elements of different implementations described herein may be combined to form other embodiments not specifically set forth above. Elements may be left out of the structures described herein without adversely affecting their operation. Furthermore, various separate elements may be combined into one or more individual elements to perform the functions described herein.