Ear insert

Abstract

An ear insert 10 comprises a generally tubular core having an inner wall defining a longitudinal channel 40 for guiding sound waves, in use, from a first end 14 to second, open, end 44. The inner wall

Description

Field of the Invention The term ‘ear insert’ used herein is intended to encompass in-ear devices such as earphones, in-ear waveguide devices, in-ear monitors and in-ear hearing aides and devices. This invention relates generally to an ear insert that, in use, is placed in a user’s ear canal to direct sound through the ear canal toward the user’s ear drum. Background of the Invention Earphones are well known and in widespread use for enabling users to hear audio signals such as music or speech. In general, an in-ear earphone comprises a generally tubular housing of some type, with an acoustic driver unit at one end and an ear bud at the other end for securing the earphone within the entrance of the user’s ear canal. It is well understood, within the field of in-ear earphone design, that there is a trade off between sound quality and the acoustic driver type (and, therefore, cost). However, all acoustic driver units are susceptible to decayed enclosure reflections that degrade the sound quality, an there are a number of earphones available now that seek to address this issue. For example, UK patent application no. GB2614033A describes an in-ear earphone having a tube that is shaped and configured to fit the user’s ear canal, and that has an inner topography shaped such that it receives sound in a straight line from the acoustic driver unit. The sound hits a first planar wall portion that acts to reflect it through 90° to a second planar wall portion. The second planar wall portion reflects the sound back through 90° and thus directs it in a straight line toward the user’s ear drum. In-ear waveguide devices are also known and used to reduce the occurrence of noise distortion created and amplified in the human ear canal, without reducing the quality or volume of the true (undistorted) sound waves reaching the tympanic membrane of a user’s ear and, indeed, improving the sound quality experienced by the user from their environment. For example, UK patent application no. GB2593205A describes an in-ear waveguide device that has an inner tube topography defining a planar reflecting region that reflects sound received from the environment, at a defined angle, toward the user’s ear drum. Both of the solutions described above for improving sound quality experienced by the user have been found to be highly effective in reducing distortion caused by reflected sound and ensuring that as many of the pure sound waves from the source (i.e. the driver or the user’s environment) reach the user’s tympanic membrane. However, when sound waves are reflected, they lose energy. Therefore, although these types of device operate highly effectively to reduce distortion and, therefore, improve the sound quality experienced by the user, this loss of energy caused by reflecting the sound waves to ‘funnel’ them toward the user’s ear drum will, inevitably, result in some loss of sound quality due to the associated loss of energy. It would, therefore, be desirable to provide an ear insert that can reduce or eliminate sound distortion caused by reflected sound waves, without loss of energy in the source sound waves, thereby further improving overall sound quality experienced by the user, and aspects of the present invention seek to address at least one or more of these issues. Statements of Invention In accordance with a first aspect of the invention, there is provided an ear insert comprising a generally tubular core having an inner wall defining a longitudinal channel for guiding sound waves, in use, from a first end thereof to second, open, end, the inner wall defining a first waveguide portion and an integral longitudinally coaxial second waveguide portion, the first waveguide portion extending, and tapering in diameter, from the first end of the channel to a tuning point along the channel, the second waveguide portion extending, and tapering in diameter, from the second end of the channel to said tuning point, such that the diameter of the channel is at its smallest at said tuning point, and the diameter of the channel at said tuning point is substantially 3.6 - 3.7 mm. The inventor has discovered that by having two tapering waveguides, extending from respective ends of the channel and meeting at a tuning point, such that the diameter of the channel is at its lowest, at 3.6 - 3.7 mm, at that tuning point, noise distortion caused by decayed reflections can be significantly reduced and the sound quality experienced by the user is significantly increased. In a preferred embodiment, the tuning point is substantially central between the first and second ends of the channel. However, this is not necessarily essential, and the tuning point could be up to substantially 3 mm either side of the centre of the channel with a barely discernible loss of sound quality. With the central point perfectly balanced between the sound source (at the first end of the channel) and the output (at the second end of the channel, closest to the user’s ear drum), the tuning point of the user’s ear can be precisely achieved using a tuning point of 3.6 - 3.7 mm, located around the midway point of the channel, connecting the two waveguide portions. This means that the optimal sound quality can be experienced by the user. The taper angle of the two waveguide portions may be the same. However, the taper angles of the waveguide portion will be dictated, at least to some extent by the physical parameters of the ear insert and the diameter of the first and second ends of the channel, as well as the overall length of the channel and the location of the tuning point. Thus, the taper angles of the two waveguide portions may be different. The lateral cross-sectional shape of the first and second waveguide portions may be substantially circular. Accordingly, the channel opening at the first end of the housing and the channel opening at the second end of the channel would also be substantially circular. In this case, the taper angle of the first waveguide portion may beneficially be between 1 and 35°, with optimum results being achievable, in an exemplary embodiment, with a taper angle of 12-15°, and a diameter of the entrance to the channel at the first end of the housing of substantially 6 - 7mm. In this case, the taper angle of the second waveguide portion may beneficially be between substantially 3.5 and 5.5°, with a diameter of the channel opening at the second end of the housing of substantially 4 - 5mm. An ear insert according to an exemplary embodiment of the invention may comprise first and second integral housing portions, the first housing portion defining the first waveguide portion and the second housing portion defining the second waveguide portion, with the tuning point located therebetween. In this case, the lateral cross section of the first housing portion could be substantially circular, but it could, alternatively, be oval. In one exemplary embodiment, the first housing portion may have a solid oval cross-section, with the first waveguide portion of circular cross-section extending therethrough. In another exemplary embodiment, the first housing portion may comprise a funnel-like portion of oval lateral cross-section, wherein the oval opening of said funnel-like portion forms the entrance to the first waveguide portion and the lateral cross-section of the first waveguide-portion is also oval. In this latter case, the entrance to the channel at the first end can, in practice, be larger than if the opening is circular e.g. an oval of width substantially 8-12 mm and length substantially 11-16 mm, and the taper angle(s) of the first waveguide portion can also be larger, and in the range 1-14° width-wise and 1 - 44° length-wise. In many of the embodiments of the ear insert device, a resiliently deformable (preferably removable) tip may be provided over the core at said second end of the channel, to allow the ear insert device to be snugly fitted within the entrance to a user’s ear canal. In some embodiments, the first end of the channel may be open, to receive sound from the user’s environment. In other embodiments, where the ear insert device is incorporated into an earphone, an acoustic driver unit may be mounted in a housing over the first end of the channel. It is to be understood that the references herein to “the taper angle” means the angle between a side wall of a waveguide portion and the longitudinal axis of the channel. These and other aspects of the invention will be apparent from the following detailed description. Brief Description of the Drawings Embodiments of the present invention will now be described, by way of examples only, and with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of an ear insert according to an exemplary embodiment of the invention; Figure 2 is a schematic longitudinal cross-sectional view of the ear insert of Figure 1; Figure 3 is a schematic plan view of an ear insert according to another exemplary embodiment of the invention; Figure 4 is a longitudinal cross-sectional view of the ear insert of Figure 3; Figure 5 is an end view (from the first end of the housing) of the ear insert of Figure 3; Figure 6 is a schematic plan view of an ear insert according to another exemplary embodiment of the invention; Figure 7 is a longitudinal cross-sectional view of the ear insert of Figure 6, viewed from a first side; and Figure 8 is a longitudinal cross-sectional view of the ear insert of Figure 6, viewed from a second side orthogonal to said first side. Detailed Description Referring to Figure 1 of the drawings, there is illustrated schematically, an ear insert according to an exemplary embodiment of the invention. The ear insert 10 comprises a generally tubular housing 12 having a first end 14 and an open, longitudinally opposing, second end 16. The second, open end 16 of the housing is shaped and configured to sit, in use, within a user’s ear canal, facing the tympanic membrane. Accordingly, the housing 12, at the second, open end 16 incorporates a first integral circumferential ridge portion 18 which extends outwardly, at an angle (of, for example 45° relative to the longitudinal axis of the housing 12), from the edge of the open end 16, along a short portion of the length of the housing 12, and terminates at a first curved recess 20. The housing 12 further comprises a second circumferential ridge portion 22 approximately halfway along the length of the housing 12. The second circumferential ridge portion 22 is defined by a circumferential ‘step’ 24 where the outer diameter of the housing 12 increases relative to the portion 26 of the housing extending between the first and second circumferential ridge portions 18, 22. A second curved recess 28 is defined between the first end of the second circumferential ridge portion 22 (defined by the ‘step’ 24) and the portion 26 of the housing extending between the first and second circumferential ridge portions 18, 22. The second circumferential ridge portion 22 widens gradually, at an angle (relative to the longitudinal axis of the housing 12) along a portion of the length of the housing 12 and terminates, by another ‘step’ 29, to a third curved recess 30. The outer diameter of the portion 26 of the housing 12 extending between the first and second circumferential ridge portions 18,22 gradually increases at a small angle (e.g. 2° relative to the longitudinal ais of the housing 12) from the first circumferential ridge portion 18 to the second circumferential ridge portion 22. An integral collar 32 forms the portion of the housing exterior, immediately adjacent the first end 14, with a substantially cylindrical portion 34 of the housing 12 extending between the third curved recess 30 and the circumferential edge of the collar 32. It will be appreciated by a person skilled in the art that the housing is beneficially moulded as a single piece, with the exterior features 18, 26, 28, 22, 30, 34, 32 formed integrally. The housing can be formed of any suitable material, such as silicone or even metal, and the present invention is not necessarily intended to be limited in this regard. Referring now additionally to Figure 2 of the drawings, a channel 40 extends through the housing from an opening 42 at the first end 14 to an opening 44 at the second end 16. In the example illustrated, the diameter of the channel opening 42 at the first end 14 of the housing 12 is greater than the diameter of the channel opening 44 at the second end 16 of the housing 12, although this is not necessarily essential. In practice, the diameter of the channel opening 44 at the second end 16 of the housing 12 is limited by the fact that, in use, it has to pass through a portion of the user’s ear canal, and the outer diameter of the first circumferential ridge 18 (which is dependent, at least to a large extent on the diameter of the channel opening 44 at the second end 16 of the housing 12) is similarly limited and may also be dictated by the need to allow a resiliently flexible tip (not shown) to be mounted thereover for use. In an exemplary embodiment, the diameter of the channel opening 44 at the second end 16 of the housing 12 may be substantially 4 - 5mm (e.g. substantially 4.6mm in one preferred example embodiment), but it will be appreciated by a person skilled in the art that this could be varied, and the present invention is not necessarily intended to be strictly limited in this regard. In use, a resiliently flexible tip, such as the type in common usage for in-ear earphones, can be fitted over the first circumferential ridge 18 of the housing, such that its edge engages in the first curved recess 22, thereby removably securing the tip over the second, open, end 16 of the housing 12. The first end 14 of the housing 12 is intended, in use, to sit adjacent the user’s tragus, outside of their ear canal, such that the opening 42 at the first end 14 of the housing 12 can be of a larger diameter than that of the opening 44 at the second end 16 of the housing 12. In an exemplary embodiment of the invention, the opening 42 at the first end 14 of the housing 12 may be substantially 6- 7mm (e.g. substantially 6.5mm in one preferred example embodiment), but it will again be appreciated by a person skilled in the art that this may be varied according to various different factors. Whilst not being limited by the inner diameter of the average user’s ear canal, there are practical limitations to the maximum diameter, including the space available between the entrance to the use’s ear canal and the tragus. However, if the overall length of the housing were such that the first end 14 protrudes further from the user’s ear canal (e.g. beyond the tragus), then the diameter of the opening 42 at the first end 14 of the housing 12 could, in theory at least, be larger. In some embodiments, where the ear insert is incorporated into an earphone, the size of the opening 42 at the first end 16 of the housing 12 may be dictated by the driver required to sit against it. Suffice it to say that the present invention is not necessarily intended to be limited in this regard. A first waveguide portion 48 extends from the opening 42 at the first end 14 of the housing 12 to a tuning point 50 located along the length of the channel 40, and an integral second waveguide portion 52 extends from the tuning point 50 to the opening 44 at the second end 16 of the housing 12. In this example, the tuning point 50 is located substantially centrally along the length of the channel 40, such that the length of both the first and second waveguide portions 48, 52 is substantially equal. However, it will be appreciated that the tuning point 50 could be located slightly off-centre (e.g. up to substantially 3mm either side of the central point along the length of the channel 40), to allow for design criteria and limitations as well as manufacturing tolerances, without significant loss of sound quality experienced by the user. The channel 40 is at its narrowest (i.e. has the smallest diameter) at the substantially central tuning point 50. Thus, the first waveguide portion 48 gradually widens along its length, at an angle (relative to the longitudinal axis of the channel 40), from the tuning point 50 to the opening 42 at the first end 14 of the housing 12; and the second waveguide portion 52 gradually widens long its length, at an angle (relative to the longitudinal axis of the channel 40) from the tuning point 50 to the opening 44 at the second end 16 of the housing 12. In the example illustrated, the angle between the side walls of the first waveguide portion 48 and the longitudinal axis of the channel 40 is approximately 13.5° and the angle between the side walls of the second waveguide portion 52 and the longitudinal axis of the cannel 40 is approximately 4.75°. Thus, in this specific example, the angle between any two diametrically opposed points along the wall of the first waveguide portion 48 is approximately 27°, and the angle between two diametrically opposed points along the wall of the second waveguide portion 52 is approximately 9.5°, with the length of each waveguide portion 48, 52 being substantially 6mm. However, it is important to appreciate that the embodiment illustrated, and the dimensions given above, are purely provided by way of examples. In practice, the length of each waveguide portion 48, 52 could vary between substantially 4 and 10 mm (and the overall length of the ear insert could, therefore, be substantially 8-20 mm) and, as stated above, they need not be precisely equal in some embodiments. The angle of the wall of the first waveguide portion 48 (relative to the longitudinal axis of the channel 40) could, in theory, be between substantially 1 and 43.5°, although in practice, at least in some embodiments, it would more practically be between substantially 22 and 32°. The angle of the wall of the second waveguide portion 52 (relative to the longitudinal axis of the channel 40) could be between substantially 1 and 7°, wherein both of these angles will ultimately be dependent on the selected diameters of the first and second openings 42, 44 and the length of the channel 40. The inventor has discovered that by providing a channel 40 incorporating a pair of integral ‘funnel-like’ waveguide portions 48, 52, end-to-end, with the narrowest point 50 located generally centrally along the length of the channel 40, between the two waveguide portions 48, 52, the narrowest point (referred to herein as “the tuning point” 50) acts to ‘tune’ the user’s ear to the sound as it reaches the tympanic membrane, thereby improving the sound quality experienced. The angled waveguide portions 48, 52 act to ensure that the sound entering the channel 40 at the opening 42 at the first end 14 of the housing 12 travels ‘smoothly’ through the channel 40 to the opening 44 at the second end 16 of the housing 12, with minimal distortion or interference by reflected sound waves. The inventor has further discovered that the optimum location of the tuning point 50 is substantially centrally along the channel 40, between the two waveguide portions 48, 52, and that the optimum diameter of the tuning point is substantially 3.6 - 3.7 mm, although it is to be understood that variations in this diameter and the location of the tuning point 50 along the channel 40, to allow for manufacturing tolerances or to suit different configurations of the ear insert 10, are possible, with barely discernible loss of sound quality experienced by the user. Referring to Figures 3 to 5 of the drawings, there is illustrated schematically an ear insert 100 according to a second exemplary embodiment of the present invention. The ear insert 100 comprises a generally tubular housing having first end 104 and an open, longitudinally opposing, second end 106. Once again, the second end 106 is shaped and configured to sit, in use, within a user’s ear canal, facing the tympanic membrane. Accordingly, the housing 102 at the second, open end 106 incorporates a first integral circumferential ridge portion 108 which extends outwardly, at and angle (of, for example, approximately 45° relative to the longitudinal axis of the housing 102), from the edge of the open end 106, along a short portion of the exterior length of the housing 102, and terminates at a first recess 110. The housing 102 further comprises a second circumferential ridge portion 112, approximately halfway along the length of the housing 102. The second circumferential ridge portion 112 is defined by a first circumferential ‘step’ 114 where the outer diameter of the housing 102 increases relative to the portion 116 of the housing 102 extending between the first and second circumferential ridge portions 108, 112. A second, curved recess 118 is defined between the first end of the second circumferential ridge portion 112 (defined by the first ‘step’ 114) and the portion 116 of the housing extending between the first and second circumferential ridge portions 108, 112. In this embodiment, the outer diameter of the second circumferential ridge portion 112 is substantially uniform. The second, longitudinally opposing, end of the second circumferential ridge portion 112 is adjacent a second circumferential ‘step’ 118 where it meets a third circumferential ridge portion 120 of oval cross-section, the longitudinal axis of which is substantially orthogonal to the longitudinal axis of the housing 102. The outer width and length of the third circumferential ridge portion 120 increases gradually from the second end of the second circumferential ridge portion 112 to the first end 104 of the housing 102. It will be appreciated that the housing 102 is beneficially moulded as a single piece, with the exterior features 102, 116 and 118 being formed integrally. The housing 102 can be formed of any suitable material, such as silicone or even metal, and the present invention is not necessarily intended to be limited in this regard. Referring now specifically to Figure 4 of the drawings, a channel 124 extends through the housing from the first end 104 to the second end 106. The entrance opening 126 to the channel 124 at the first end 104 of the housing 102 is of substantially circular crosssection. Thus, an oval, substantially planar surface 129 is defined at the first end 104 of the housing 102, through which the entrance opening 126 to the channel 124 extends. In the example illustrated, the length and width of the oval-shaped surface 129 of the third circumferential ridge portion portion 120 are greater than the diameter of the housing 102 at its second end 106. In practice, the diameter of the second end 106 of the housing 102 is limited by the fact that, in use, it has to pass through a portion of the user’s ear canal, and the outer diameter of the first circumferential ridge portion 108 is similarly limited, and may be dictated by the need to allow a resiliently flexible tip (not shown) to be mounted thereover for use. In an exemplary embodiment, the diameter of the channel opening 128 at the second end 106 of the housing 102 may be substantially 4-5 mm (e.g. substantially 4.6 mm in one preferred example embodiment), but it will be appreciated by a person skilled in the art that this could be varied, at least by a small amount, and the present invention is not necessarily intended to be limited in this regard. In use, a resiliently flexible tip, such as the type in common usage for in-ear earphones, can be fitted over the first circumferential ridge portion 108 of the housing 102, such that its edge engages in the first recess 110, thereby removably securing the tip over the second, open, end 106 of the housing 102. In this exemplary embodiment, the first end 104 of the housing 102 is intended, in use, to sit adjacent the user’s tragus, just outside their ear canal, such that the dimensions of the substantially oval surface 129 at the first end 104 of the housing 102 can be larger than the diameter of the housing 103 at the second end 106 and, therefore, the entrance opening 126 to the channel 124 at the first end 104 can be larger than the opening 128 at the second end 106 of the housing 102. In an exemplary embodiment of the invention, the oval surface 129 at the first end of the housing 102 may be of (outer) width 8-10 mm and (outer) length 12-14 mm. However, it will be appreciated that this is, at least in part, dependent on the diameter of the entrance opening 126 to the channel, and could be varied according to various design characteristics. It is thought that the oval surface could have a width range of substantially 4-14 mm and a length range of substantially 7-17 mm, and it will again be appreciated by a person skilled in the art that these dimensions can be varied according to various different factors, and the present invention is not necessarily intended to be limited in this regard. The oval shape of the first end 104 of the housing, and particularly the oval surface 129, which is intended to sit in the user’s ear between the front of the tragus and the entrance to the ear canal, is beneficial in that it better fits and fills the ear cavity in that region and, therefore, acts to help to prevent incoming sound from being reflected from the walls of the ear cavity and distorting the incoming sound waves. If the overall length of the ear insert were such that it extends beyond the ear cavity between the tragus and the entrance of the ear canal, in use, the outer dimensions of the third circumferential ridge portion 120 could, in theory, be larger still. Referring particularly to Figure 5 of the drawings, the channel 124 comprises a first waveguide portion 130 that extends from the entrance opening 126 at the first end 104 of the housing 102, gradually decreasing in diameter, to a narrowest point (hereinafter referred to as the tuning point) 132 located along the length of the channel 124. In this specific example, the first waveguide portion 130 extends longitudinally through the thickness of the third circumferential ridge portion 120, gradually decreasing in diameter to the tuning point, which is located adjacent the base of the third circumferential ridge portion 120, at the second end of the second circumferential ridge portion 112. However, this is not absolutely essential, and will be dependent on the various lengths and dimensions of the various (outer) elements of the housing 102. An integral second waveguide portion 134 extends from the tuning point 132, gradually increasing in diameter, to the opening 128 at the second end 106 of the housing 102. In this example, the tuning point 132 is located substantially centrally along the length of the channel 124, such that the length of both the waveguide portions 130, 134 is substantially equal. However, it will be appreciated that the tuning point 132 could be located slightly off-centre in some embodiments (e.g. up to substantially 3mm either side of the central point along the length of the channel 124), to allow for design criteria and limitations, as well as manufacturing tolerances, with little discernible loss of sound quality experienced by the user. The channel 124 is at its narrowest (i.e. has the smallest diameter) at the substantially central tuning point 132. Thus, the first waveguide portion 130 gradually widens along its length, at an angle (relative to the longitudinal axis of the channel 124) from the tuning point 132 to the entrance opening 126 at the first end 104 of the housing 102; and the second waveguide portion 134 gradually widens along its length, at an angle (relative to the longitudinal axis of the channel 124) from the tuning point 132 to the opening 128 at the second end 106 of the housing 102. In the example illustrated, the angle between the side walls of the first waveguide potion 130 and the longitudinal axis of the channel 124 is approximately 13.5° and the angle between the side walls of the second waveguide potion 134 and the longitudinal axis of the channel 124 is approximately 4.75°. Thus, in this specific example, the angle between any two diametrically opposite points along the side wall of the first waveguide portion 130 is approximately 27°, and the angle between any two diametrically opposite points along the side wall of the second waveguide portion 134 is approximately 9.5°, with the length of each waveguide portion 130, 134 being substantially equal and approximately 6 mm. However, it is important to appreciate that the embodiment illustrated and described above, and the dimensions given, are provided by way of examples in relation to one ‘optimum’ example embodiment of the invention. In practice, the length of each waveguide portion 130, 134 could vary between substantially 4 and 10 mm (and the overall length of the ear insert could, therefore, be substantially 8-20 mm) and, as stated above, they need not be precisely equal in some embodiments. The angle of the wall of the first waveguide portion 130 (relative to the longitudinal axis of the channel 124) could, in theory, be between 1 and 43.5°, although in practice, at least in some embodiments, it would be more likely (and practically) be between substantially 20 and 35°. The angle of the wall of the second waveguide portion 134 (relative to the longitudinal axis of the channel 124) could be between substantially 1 and 7°, wherein both of these angles will ultimately be dependent on the selected diameters of the first and second openings 126, 128 and the length of the channel (and, therefore, the lengths of the first and second waveguide portions 130, 134). The inventor has discovered that by providing a channel 124 incorporating a pair of integral ‘funnel-like’ waveguide portions 130, 134, end-to-end, with the narrowest point 132 located generally centrally along the length of the channel 124, between the two waveguide portions 130, 134, the narrowest point (herein referred to as ‘the tuning point’ 132) acts to ‘tune’ the user’s ear to the sound as it reaches the tympanic membrane, thereby improving the sound quality experienced by a highly unexpected and surprising degree. The angles waveguide portions 130, 134 act to ensure that the sound entering the channel 124 at the opening 126 at the first end 104 of the housing 102 travels ‘smoothly’ through the channel 124 to the opening 128 at the second end 106 of the housing 102, with minimal distortion or interference by reflected sound waves. Referring now to Figures 6 to 8 of the drawings, a third example ear insert 200 is illustrated schematically. The ear insert 200 comprises a generally tubular housing having first end 204 and an open, longitudinally opposing, second end 206. Once again, the second end 206 is shaped and configured to sit, in use, within a user’s ear canal, facing the tympanic membrane. Accordingly, the housing 202 at the second, open end 206 incorporates a first integral circumferential ridge portion 208 which extends outwardly, at and angle (of, for example, approximately 45° relative to the longitudinal axis of the housing 202), from the edge of the open end 206, along a short portion of the exterior length of the housing 202, and terminates at a first recess 210. The housing 202 further comprises a second circumferential ridge portion 212, approximately halfway along the length of the housing 202. The second circumferential ridge portion 212 is defined by a first circumferential ‘step’ 214 where the outer diameter of the housing 202 increases relative to the portion 216 of the housing 202 extending between the first and second circumferential ridge portions 208, 212. A second, curved recess 218 is defined between the first end of the second circumferential ridge portion 212 (defined by the first ‘step’ 214) and the portion 216 of the housing extending between the first and second circumferential ridge portions 208, 212. In this embodiment, the outer diameter of the second circumferential ridge portion 212 is substantially uniform. The second, longitudinally opposing, end of the second circumferential ridge portion 212 is adjacent a second circumferential ‘step’ 219 where it meets a ‘funnel’-like portion 220 of oval cross-section, the longitudinal axis of which is substantially orthogonal to the longitudinal axis of the housing 202. The outer and inner widths and lengths of the funnel-like portion 220 increase gradually from the second end of the second circumferential ridge portion 212 to the first end 204 of the housing 202. It will be appreciated that the housing 202 is beneficially moulded as a single piece, with the exterior features 208, 212 and 220 being formed integrally. The housing 202 can be formed of any suitable material, such as silicone or even metal, and the present invention is not necessarily intended to be limited in this regard. Referring now specifically to Figures 7 and 8 of the drawings, a channel 224 extends through the housing from the first end 204 to the second end 206. The entrance opening 226 to the channel 224 at the first end 104 of the housing 102 is, in effect, the oval opening of the funnel-like portion 220 of the housing 202, and the second channel opening 228, which is of circular cross-section is at the second end 206 of the housing 202. In the example illustrated, the length and width of the oval cross-section of the funnellike portion 220 of the housing 202 can be greater than the diameter of the housing 202 at its second end 206. In practice, the diameter of the second end 206 of the housing 202 is limited by the fact that, in use, it has to pass through a portion of the user’s ear canal, and the outer diameter of the first circumferential ridge portion 208 is similarly limited, and may be dictated by the need to allow a resiliently flexible tip (not shown) to be mounted thereover for use. In an exemplary embodiment, the diameter of the channel opening 228 at the second end 206 of the housing 202 may be substantially 4-5 mm (e.g. substantially 4.6 mm in one preferred example embodiment), but it will be appreciated by a person skilled in the art that this could be varied, at least by a small amount, and the present invention is not necessarily intended to be limited in this regard. In use, a resiliently flexible tip, such as the type in common usage for in-ear earphones, can be fitted over the first circumferential ridge portion 208 of the housing 202, such that its edge engages in the first recess 210, thereby removably securing the tip over the second, open, end 206 of the housing 202. In this exemplary embodiment, the first end 204 of the housing 202 is intended, in use, to sit adjacent the user’s tragus, just outside their ear canal, such that the dimensions of the substantially oval outer of the funnel-like portion 220 of the housing 202 can be larger than the diameter of the housing 202 at the second end 206 and, therefore, the entrance opening 226 to the channel 224 at the first end 204 can be larger than the opening 228 at the second end 206 of the housing 202. In an exemplary embodiment of the invention, the oval channel opening 226 at the first end of the housing 202 may be of (outer) width 8-9 mm and (outer) length 12-13 mm. In another exemplary embodiment, the outer width may be 11.5 - 12.5 mm and the outer length may be 15.5 - 16.5 mm. However, it will be appreciated that this could be varied according to various design characteristics. It is thought that the outer oval circumference of the funnel-like portion 220 could have a width range of substantially 4-14 mm and a length range of substantially 7-17 mm, and it will again be appreciated by a person skilled in the art that these dimensions can be varied according to various different factors, and the present invention is not necessarily intended to be limited in this regard. The oval circumferential shape of the first end 204 of the housing, which is intended to sit in the user’s ear between the front of the tragus and the entrance to the ear canal, is beneficial in that it better fits and fills the ear cavity in that region and, therefore, acts to “funnel” more sound waves into the user’s ear and help to prevent incoming sound from being reflected from the walls of the ear cavity and distorting the incoming sound waves. If the overall length of the ear insert were such that it extends beyond the ear cavity between the tragus and the entrance of the ear canal, in use, the outer dimensions of the funnel-like portion 220 could, in theory, be larger still. Referring particularly to Figures 7 and 8 of the drawings, the channel 224 comprises a first waveguide portion 230, that is formed by the inner circumferential wall of the funnellike portion 220, extends from the entrance opening 226 at the first end 204 of the housing 202, gradually decreasing in diameter, to a narrowest point (hereinafter referred to as the tuning point) 232 located along the length of the channel 224. In this specific example, the first waveguide portion 230 extends longitudinally through the funnel-like portion 220, gradually decreasing in diameter to the tuning point, which is located adjacent the base of the third circumferential ridge portion 220, at the second end of the second circumferential ridge portion 212. An integral second waveguide portion 234 extends from the tuning point 232, gradually increasing in diameter, to the opening 228 at the second end 206 of the housing 202. In this example, the tuning point 232 is located substantially centrally along the length of the channel 224, such that the length of both the waveguide portions 230, 234 is substantially equal. However, it will be appreciated that the tuning point 232 could be located slightly off-centre in some embodiments (e.g. up to substantially 3mm either side of the central point along the length of the channel 224), to allow for design criteria and limitations, as well as manufacturing tolerances, with little discernible loss of sound quality experienced by the user. The channel 224 is at its narrowest (i.e. has the smallest diameter) at the substantially central tuning point 232. Thus, the first waveguide portion 230 (which has an oval cross-section) gradually widens (length-wise and width-wise) along its ‘height’, at an angle (relative to the longitudinal axis of the channel 224) from the tuning point 232 to the entrance opening 226 at the first end 204 of the housing 202; and the second waveguide portion 234 gradually widens along its length, at an angle (relative to the longitudinal axis of the channel 224) from the tuning point 232 to the opening 228 at the second end 206 of the housing 202. In the example illustrated, the angle between the side walls at the widest point of the first waveguide portion 230 and the longitudinal axis of the channel 224 is approximately 24° (see Figure 7) and the angle between the side walls at the widest part of the second waveguide potion 234 and the longitudinal axis of the channel 224 is approximately 38° (Figure 8). Thus, in this specific example, the angle between two opposite points across the width of the side wall of the first waveguide portion 230 is approximately 48° (Figure 7) and the angle between two opposite points across the length of the side wall of the second waveguide portion 234 is approximately 76° (Figure 8) with the length of each waveguide portion 230, 234 being substantially equal and approximately 6 mm. However, it is important to appreciate that the embodiment illustrated and described above, and the dimensions given, are provided by way of examples in relation to one ‘optimum’ example embodiment of the invention. In practice, the length of each waveguide portion 230, 234 could vary between substantially 4 and 10 mm (and the overall length of the ear insert could, therefore, be substantially 8-20 mm) and, as stated above, they need not be precisely equal in some embodiments. The angle of the wall of the first waveguide portion 230 (relative to the longitudinal axis of the channel 224) could, in theory, be between 1 and 44° (width-wise or and / or length-wise) although in practice, at least in some embodiments, it would be more likely (and practically) be between substantially 15 and 45°. The angle of the wall of the second waveguide portion 234 (relative to the longitudinal axis of the channel 224) could be between substantially 1 and 7°, wherein both of these angles will ultimately be dependent on the selected diameters of the first and second openings 226, 228 and the length of the channel (and, therefore, the lengths of the first and second waveguide portions 230, 234). The inventor has discovered that by providing a channel 224 incorporating a pair of integral ‘funnel-like’ waveguide portions 230, 234, end-to-end, with the narrowest point 232 located generally centrally along the length of the channel 224, between the two waveguide portions 230, 234, the narrowest point (herein referred to as ‘the tuning point’ 232) acts to ‘tune’ the user’s ear to the sound as it reaches the tympanic membrane, thereby improving the sound quality experienced by a highly unexpected and surprising degree. The angles waveguide portions 230, 234 act to ensure that the sound entering the channel 224 at the opening 226 at the first end 204 of the housing 202 travels ‘smoothly’ through the channel 224 to the opening 228 at the second end 206 of the housing 202, with minimal distortion or interference by reflected sound waves. The inventor has further discovered that the optimum location of the tuning point 232 is substantially centrally along the channel 124, between the two waveguide portions 230, 234, and that the optimum diameter of the tuning point 232 is substantially 3.6 - 3.7 mm, although it is to be understood that small variations in the diameter and location of the tuning point 232, to allow for manufacturing tolerances and design limitations and requirements, are possible, with barely discernible loss of sound quality. Some embodiments of the ear insert 10, 100, 200 could be utilised for enhancing the sound quality experienced by a user in relation to sound being generated within an environment. For example, to enhance the user’s enjoyment of a music concert or cinema experience. Other embodiments of the ear insert could be incorporated into an earphone including a driver located adjacent the opening 42, 126, 226 at the first end 14, 104, 204 of the housing 10, 102, 202. The ear insert may, in some embodiments, include a circumferential (external) sheath (not shown) located around the opening 42, 126, 226 at the first end 14, 104, 204 of the housing 12, 102, 202. The sheath may be integral with, affixed to or removably secured to the housing 12, 102, 202. The sheath acts, in use, to block and / or deflect reflected sound waves from the shell of the user’s ear such that those reflections do not enter the channel 40, 124, 224 and distort the sound waves received at the user’s tympanic membrane. The sheath may comprise a resiliently deformable or rigid ear piece that fits in the cavity between the tragus and the inner wall of user’s ear shell. The sheath may be custom made to fit precisely within a specific user’s ear cavity, or it may, for example, be formed of silicone (or other resiliently flexible material, to allow a user to ‘mould’ the ear piece to the shape of their inner ear cavity. In other embodiments, the sheath may be shaped and configured to deflect, rather than block, reflected sound waves from the ear shell defining the inner ear cavity. It will be apparent to a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiment without departing from the scope of the invention as defined by the appended claims.

Claims

1. An ear insert comprising a generally tubular core having an inner wall defining a longitudinal channel for guiding sound waves, in use, from a first end thereof to second, open, end, the inner wall defining a first waveguide portion and an integral longitudinally coaxial second waveguide portion, the first waveguide portion extending, and tapering in diameter, from the first end of the channel to a tuning point along the channel, the second waveguide portion extending, and tapering in diameter, from the second end of the channel to said tuning point, such that the diameter of the channel is at its smallest at said tuning point, and the diameter of the channel at said tuning point is substantially 3.6 - 3.7 mm.

2. An ear insert according to claim 1, wherein the tuning point is substantially central between the first and second ends of the channel such that the lengths of said first and second waveguide portions are substantially equal.

3. An ear insert according to claim 1, wherein the tuning point is located up to substantially 3 mm either side of the centre of the channel.

4. An ear insert according to any of claims 1 to 3, wherein the taper angles of the first and second waveguide portions are different.

5. An ear insert according to any of the preceding claims, wherein the lateral cross-sectional shape of the first and second waveguide portions is substantially circular.

6. An ear insert according to claim 5, wherein the taper angle of the first waveguide portion is between 1 and 35°7. An ear insert according to claim 5 or claim 6, wherein the taper angle of the first waveguide portion is 12 -15° and the diameter of said channel at said first end of said housing is substantially 6-7 mm.

8. An ear insert according to any of the preceding claims, comprising first and second integral housing portions, the first housing portion defining the first waveguide portion and the second housing portion defining the second waveguide portion, with the tuning point located therebetween.

9. An ear insert according to claim 8, wherein the lateral cross-section of the first housing portion is substantially circular.

10. An ear insert according to claim 8, wherein the lateral cross-section of the first housing portion is substantially oval.

11. An ear insert according to claim 10, wherein the first housing portion has a solid oval lateral cross-section, with a first waveguide portion of circular cross-section extending longitudinally therethrough.

12. An ear insert according to claim 10, wherein the first housing portion comprises a funnel-like portion of oval lateral cross-section, wherein the oval opening of said funnellike portion forms the entrance to the first waveguide portion and the lateral crosssection of the first waveguide-portion is also oval.

13. An ear insert according to claim 13, wherein the entrance to the channel at the first end is an oval of width substantially 8-12 mm and length substantially 11-16 mm.

14. An ear insert according to claim 13 or claim 14, wherein the taper angle(s) of the first waveguide portion are in the range substantially 1-14° width-wise and substantially 1 - 44° length-wise.

15. An ear insert according to any of the preceding claims, wherein the taper angle ofthe second waveguide portion is between substantially 1 and 7°.

16. An ear insert according to any of the preceding claims, wherein the taper angle of the second waveguide portion is substantially 4 -5° and the diameter of said channel at said second end of said housing is substantially 4 - 5mm.

17. An ear insert according to any of the preceding claims, further comprising a resiliently deformable tip over the core at said second end of the channel.

18. An ear insert according to any of the preceding claims, further comprising anexternal sheath located around said first end of said housing, the sheath being shaped and configured to, in use, block and / or deflect reflected sound waves from within auser’s ear cavity, and thereby prevent such reflected sound waves from entering said longitudinal channel.

19. An in-ear waveguide device, comprising an ear insert according to any of the preceding claims, wherein the first end of the channel is open to receive, in use, sound 5 from a user’s environment.

20. An earphone comprising an ear insert according to any of claims 1 to 18, and an acoustic driver unit mounted in a housing over the first end of the channel.

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