Abstract:
A hearing protector, including a sealing body with a channel, and a muffling device which is connected to the sealing body and connects to the channel. When the sealing body is placed in an auditory canal, the channel extends between the auditory canal and the atmosphere. The channel has a distal end part at the side of the auditory canal and a proximal end part at the side of the atmosphere. The muffling device connects to the proximal end part of the channel and includes a rotatable control element, provided with at least one through aperture. The muffling device also includes a housing element provided with at least one through aperture. The control element and the housing element are rotatable relative to each other between two or more discrete rotation positions with corresponding muffling value. The apertures in the control element and the housing element overlap each other to a greater or lesser extent depending on a mutual angle of rotation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of copending application International Application No. PCT/NL99/00031, filed on Jan. 18, 1999, and which designated the U.S. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a hearing protector intended for placing in an auditory canal of a user. The hearing protector includes a sealing body with a channel extending through it and a muffling device which is connected to the sealing body and connects to the channel. The sealing body is adapted to be placed in an auditory canal, so that the channel extends between the auditory canal and the atmosphere, in which the channel has a distal end part at the side of the auditory canal and a proximal end part at the side of the atmosphere. The muffling device connects to the proximal end part of the channel and comprises a rotatable control element, which control element is provided with at least one through aperture. The muffling device further comprising a housing element, which housing element is provided with at least one through aperture, the control element and the housing element being rotatable relative to each other between rotational positions with a corresponding muffling value, with the result that the apertures in the control element and the housing element overlap each other to a greater or lesser extent depending on a mutual angle of rotation. 
     BACKGROUND OF THE INVENTION 
     Such a hearing protector is known from DE-A-40 08 982, which discloses a substantially solid sealing body which is made to measure for a particular user (otoplastic). The sealing body contains an aeration channel which is widened at the proximal end part. A muffling device is fitted in the widened end part. The muffling device consists of a cylindrical element which is provided with a through aperture. The through aperture is made eccentrically in the element, the diameter of the aperture corresponding approximately to the diameter of the aeration channel. On the front side, the element is provided with a slot in which a screwdriver can engage. In this way, the element can be rotated relative to the sealing device, with the result that the aeration channel is cleared to a greater or lesser extent by the through aperture. 
     A disadvantage with this known hearing protector is that the muffling device is difficult to control. If a specific muffling value is desired, said value is difficult or impossible to set or distinguish. The design of the muffling element is intended in particular for otoplastics, and it is ill suited for use on a hearing protector with a sealing body of a more open design intended for universal use. In the open position of the muffling device, inadequate sound muffling can be achieved as a result of the relatively large diameter of the through aperture in the cylindrical element. In the fully closed position of the muffling device, undesired acoustic leakage still occurs. Moreover, the muffling device cannot be controlled without an aid. 
     EP-A-0 333 298 and DE-U-93 13 061 disclose hearing protectors with muffling devices, in which the muffling device comprises a housing which is fixed in the channel of the sealing body and comprises a central bore, consisting of a cylindrical threaded part and a part which tapers in the distal direction. A correspondingly threaded adjusting pin, which is formed such that it is complementary to the tapering part of the bore, fits into the bore, which pin can be moved in the axial direction by rotation in the bore, with the result that the passage to the open environment can be adjusted. This permits a stepless adjustment of the passage, and thus of the muffling action of the muffling device. Said stepless adjustment of the muffling action is used for having the muffling action set once by a manufacturer, by way of measurement, at a value specified by a user. 
     As in the case of DE-A-40 08 982, it is also a disadvantage in this type of hearing protector that the muffling device is difficult to control. Any change in the muffling value to a different muffling value will usually have to be carried out again by the manufacturer by means of rotating the adjusting pin and at the same time measuring the muffling value. The setting of the muffling value will generally not be changed by the user. However, if the user still changes the setting of the muffling device himself, it will have to be carried out by feel, and there is a risk here that a muffling effect which is correct by feel will turn out to be too low a muffling value in certain circumstances, so that the user, without noticing it, runs the risk of hearing loss in the long run. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to overcome the abovementioned disadvantages, and in particular to provide a hearing protector in which several desired muffling values of a muffling device can be adjusted quickly, reliably and in a reproducible manner by a user himself. Another object of the invention is to provide a muffling device which is suitable for combining with a sealing body designed for universal use. 
     These objects are achieved according to the invention including a hearing protector. The muffling device comprises a housing element which has at least one through aperture. The elements are rotatable relative to each other between two or more discrete rotation positions with corresponding muffling values. In the discrete rotation positions the apertures in the elements overlap to a greater or lesser extent, depending on the mutual angle of rotation. Various specific muffling values, determined in advance by a manufacturer, can advantageously be set by the user himself in a simple and reproducible manner. The dimensions of the muffling device do not change when the muffling device is adjusted to another muffling value set during use. This provides a very compact hearing protector with adjustable muffling value. The control element and the housing element are provided with complementary position-indicating means, for indicating the two or more discrete rotation positions. Herewith the complementary position-indicating means comprise parts which, through a rotation of the elements relative to each other, snap or click into each other. The muffling device in each case can be rotated until a click is heard and/or felt by the user, which indicates that the muffling device is situationed in a discrete rotational position. If desired, the rotation of the muffling device may also be carried out when the hearing protector is in the user&#39;s ear. 
     The hearing protector with the muffling device according to the invention is suitable in particular for use with a sealing body suitable for universal use. Such sealing bodies are known in many forms; see, for example, NL-A-94 01 212 and U.S. Pat. No. 4, 540 063. However, there is still room for improvement in the wearing comfort and the muffling characteristics of these known sealing bodies. The present invention now provides a hearing protector with a muffling device in which a sealing body is provided which, on the one hand, gives optimum wearing comfort and, on the other hand, in the specific combination with the muffling device according to the invention results in desired muffling characteristics. To this end, the sealing body comprises a central tube having a channel therein, at least one shell provided on the tube and designed to rest in a sealing manner against an auditory canal, and an end wall bounding the distal end part of the channel and having an end edge part of elastically deformable material which is bent inwards in the radial direction. In this case the end edge part is dimensioned in such a way that it deforms elastically in the axial direction under an axial pressure load, for example as a result of fitting the sealing body in an auditory canal. Thus a hearing protector is provided having a universal sealing body made of a flexible plastic which can shut off the auditory canal of different persons without in the process exerting unpleasant or painful pressure on the walls of the auditory canal. With the hearing protector designed in this way, the readily deformable front wall part of the sealing body will yield in the optimum manner, while effective insertion of the earplug body in the auditory canal is still ensured. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in greater detail below with reference to an exemplary embodiment shown in the drawing, in which: 
     FIG. 1 is a view in perspective of a hearing protector according to the invention; 
     FIG. 2 is a view in longitudinal section of FIG. 1; 
     FIG. 3 is a view in cross section on an enlarged scale along the line III—III in FIG. 2; 
     FIG. 4 is a view in cross section along the line IV—IV in FIG. 2, in which view the sealing device being omitted; 
     FIG. 5 is a view in longitudinal section of a second embodiment of a hearing protector according to the invention; 
     FIG. 6 is a view in perspective of the housing element of the muffling device in FIG. 5; 
     FIG. 7 is a view in longitudinal section of FIG. 6; 
     FIG. 8 is a top view of FIG. 7; 
     FIG. 9 is a view in perspective of the control element of the muffling device in FIG. 5; 
     FIG. 10 is a view in longitudinal section on an enlarged scale of FIG. 9; 
     FIG. 11 is a front view of FIG. 9; 
     FIG. 12 is a top view of FIG. 11; and 
     FIG. 13 is a view in longitudinal section of a third embodiment of a hearing protector according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The hearing protector is indicated in its entirety by the reference numeral  1  in FIG. 1, and comprises a sealing body  2  and a muffling device  3 . The sealing body will be explained in further detail below. The sealing body  2 , which is made from a flexible material, for example a thermoplastic elastomer, is intended for placing in an auditory canal of a user. The sealing body  2  is designed in such a way that when placed in the auditory canal of the user a seal is obtained all the way around against the wall of the auditory canal. 
     A channel  4  (see FIG. 2) is present in the central part of the sealing body  2 , which channel in use forms an air communication between the auditory canal and the open environment. The channel  4  comprises a distal end part at the side of the auditory canal and a proximal end part at the side of the open environment. The channel  4  comprises a widened part at the proximal end. A muffling device  3  is placed in this widened part  5 . 
     The muffling device  3  comprises a tubular housing element  6 , which is fitted in the widened part  5  and rests with an outward directed flange  8  against the end of the widened part  5 . The flange  8  ensures that the housing element  6  cannot be pressed further into the channel  4 . The flange  8  is provided on the periphery with eight lips  9 , uniformly distributed along the periphery, and each provided with an inward directed snap groove  10 . 
     The part of the relatively rigid housing element  6  which is placed in the widened part  5  has an external diameter which is slightly larger than the internal diameter of the widened part  5 . When the relatively rigid housing element  6  is placed in the flexible widened part  5 , a close fit of the housing element in the widened part  5  will be produced, so that the housing element  6  will stay in position in the widened part  5  during use of the hearing protector  1 . 
     At the end facing the channel  4 , the housing element  6  is provided with an end wall  11 , in which a through aperture  18  is provided. The through aperture  18  is formed here by breaking through half of the end wall  11  (see FIG.  4 ). 
     A tubular control element  7  is placed in the housing element  6 . The control element  7  has a muffling part projecting into the housing element  6 , and a control part projecting outside the housing element  6 . The control part is widened in the radial direction relative to the muffling part. The control part is provided with a snap edge  12 , which engages in the snap grooves  10  of the lips  9  when the control element  7  is inserted into the housing element  6 , with the result that the control element  7  is locked against axial displacement relative to the housing element  6 . Fixing the control element in the axial direction relative to the housing element can also be carried out in another way. The embodiment with the snap edge  12  has the advantage that not only is the control element  7  fixed in the axial direction in the housing element  6 , but replacement of the control element  7  by another control element  7 , for example with other muffling values, can also be carried out easily if necessary. The control element  7  and the housing element  6  fit rotatably into each other. The control part serves as a knob which can easily be taken between the fingers, in order to rotate the control element  7  relative to the housing element  6 , thus setting the muffling value of the muffling device  3 . 
     The control element  7  is provided with an end wall  13  at the end facing the channel  4 . The end wall  13  is provided with two through apertures  14 ,  15  with different diameters (see FIG.  3 ). The diameters of the through apertures  14  and  15  are small compared with the diameter of the channel  4 , and are, for example, approximately 0.3 and 0.1 mm. The small through apertures ensure a good sound reduction, while ensuring that voice sounds are still audible. 
     A muffling device with three different muffling values is thus obtained, namely the muffling values belonging to the through apertures  14  and  15  and a maximum muffling value belonging to a rotational position of the control element  7  in the housing element  6 , where no air communication is present between the auditory canal and the environment by way of the channel  4 . In the case of the maximum muffling value, the two through apertures  14  and  15  are situated opposite the part of the end wall  11  of the housing element  6  which is without through apertures. 
     The through apertures  14  and  15  and the position with the maximum muffling value are situated at equal angular distances from each other. In addition, the through apertures  14  and  15  and the position with the maximum muffling value are situated on a circle in the example shown, but this is not necessary. In a variant, several through apertures are provided in the housing element and one through aperture in the control element. 
     The elements  6 ,  7  are provided with complementary position-indicating means. A projection  16  is provided on the outside wall of the muffling part. The projection  16  interacts with three recesses  17  present in the inside wall of the housing element  6  (see FIG.  3 ). The recesses  17  are placed at the same angular distances from each other as the through apertures  14  and  15  and the position with maximum muffling. In the example shown, the projection  16  engages on the side of the position with the maximum muffling value by snapping or clicking into one of the recesses  17 . By means of elastic deformation of the projection  16 , when the control element  7  is rotated, a “clicking force” must be overcome in each case in order to move the projection  16  into one of the other recesses  17 . The rotational position in which the control element  7  is situated is preferably marked on the outside of the control part. 
     The operation of the muffling device  3  will be explained below with reference to FIG.  2 . 
     In the rotational position of the control element  7  relative to the housing element  6  shown in FIG. 2, the through aperture  15  in the end wall  13  is situated below the through aperture  18  in the end wall  11 . This means that the channel  4 , and consequently the auditory canal of the user, has an air communication with the environment by way of the through aperture  15 . The muffling device  3  in this position has a muffling value which corresponds to the through aperture  15 . When the control element  7  is subsequently rotated from the rotational position shown in FIG. 2 in an anticlockwise direction until the projection  16  engages in the next recess  17 , the through aperture  14  comes to rest below the through aperture  18 . In this way the muffling device  3  is set at a muffling value corresponding to the through aperture  14 . On further rotation of the control element  7 , a part of the end wall  13  without through aperture subsequently comes to rest below the through aperture  18 , with the result that no air communication is present between the auditory canal of the user and the environment by way of the channel  4 . The muffling device  3  has then been set at the maximum muffling value. 
     Although three discrete rotational positions with corresponding muffling values are given in the exemplary embodiment described above, it is clear that more rotational positions with corresponding muffling values can be provided, for example by providing more through apertures in the end wall of the control element. It is then best to make the through aperture in the housing element smaller, so that in each case only the desired through aperture(s) of the control element come to rest in an overlapping relationship with the through aperture in the housing element. 
     The relatively rigid muffling device  3 , which is made of, for example, PP or POM, advantageously provides the sealing body  2  with a certain rigidity. This means that the hearing protector  1  can be inserted more easily into the auditory canal, while the muffling device can also be easily controlled by hand. 
     The hearing protector in FIG. 5 comprises a sealing body  25  and a muffling device  26 . The sealing body will be explained in greater detail below. The muffling device  26  is, on the whole, the same as the muffling device  3  in FIGS. 1-4, and again comprises a tubular housing element  27  and a tubular control element  28 . The elements  27 ,  28  engage rotatably in each other, in which an axial locking is ensured by two interacting snap edges  30 ,  31 . Three recesses  33  and projections  32  distributed along the periphery are provided on the housing element  27  and the control element  28  respectively. The recesses  33  and the projections  32  together form the complementary position-indicating means. 
     For the sake of clarity, the housing element  27  and the control element  28  are shown separately in FIGS. 6-8 and FIGS. 9-12 respectively. The housing element  27  is provided with one through aperture  35  in its end wall (see FIG. 7,  8 ). The control element  28  is provided with two through apertures  36 ,  37  in its end wall (see FIG.  12 ). The through aperture  35  here is a round recess with a relatively small diameter. The through aperture  35  is situated on the same radius as the through apertures  36 ,  37 . 
     The control element  28  is provided with three grooves  40  extending in the axial direction on its control part. Said grooves  40  contribute to a better grip of a user on the control part. The grooves  40  each have a widened part on their free end. The individual widened parts have differing depths, by means of which the rotational position in which the control element  28  is situated can be established. For example, the greatest depth goes with the smallest muffling value. 
     Although in the drawing a hearing protector having a combination of an adjustable muffling device with a sealing body of the type for universal use is shown, the hearing protector can also comprise an otoplastic. 
     The adjustable muffling devices described above are suitable in particular for use with sealing bodies of the type for universal use. In the case of the embodiment according to the invention in FIGS. 1 and 2, the sealing body  2  is made of a flexible, elastic material, which is, furthermore, suitable for multiple use of the hearing protector over a longer period of time of, for example, several years. The manufacture of the sealing body  2  can be carried out by, for example, injection moulding. 
     The sealing body  2  comprises a central tube  50 , which bounds the through channel  4  with a wall. Two shells  51  and  52  are provided on the central tube  50 . In use, the shells  51  and  52  rest against the wall of the auditory canal of the user and against the opening edge of the auditory canal respectively. 
     The distal end part of the channel  4  is bounded by an end wall  55 . The end wall  55  comprises an end edge part  56 , which is bent inwards in the radial direction. Under a load, the end edge part  56  will deform in the axial direction and be pressed inwards. The end wall  55  further comprises a central part  57 , which is formed curving outwards in the radial direction. The distal end part of the channel  4  bounded by the end wall  55  is widened in a correspondingly spherical shape. 
     At the place where the wall of the central tube  50  merges into the end wall  55 , the shell  51  connects to the outer periphery of the tube  50 . The shell  51  is designed like a parachute, the concave side facing the proximal end part of the channel  4 . 
     Further engaging upon the outer periphery of the wall of the tube  50  is the second parachute-like shell  52 , which is situated closer to the proximal end part, and the concave side of which likewise faces the proximal end part. The dimensions of the second shell  52  are such that said shell comes to rest in a sealing manner against the opening edge of an auditory canal. The shell  52  thus ensures that the sealing body is not inserted too far into the auditory canal. 
     When the sealing device  2  is being placed in the auditory canal of a user, the end wall  55  will be stopped in the axial direction on its end edge part  56 . The ensuing axial deformation of the end edge part  56  ensures that the central part  57  will expand in the radial direction, with the result that the central part  57  will come to rest in a sealing manner against the wall of the auditory canal. With this the radial dimensions of the central part  57  are selected in such a way that the sealing device  2  is easy to place in the auditory canal. 
     The specific deformation of the front part of the sealing body ensures that irritating pressure points in the auditory canal of the user are prevented, and the sealing body placed in the auditory canal will generally feel comfortable. The user will consequently be less inclined to remove the hearing protector from the auditory canal while being exposed to excessive noise. The spherical central part also seals off very well against the wall of the auditory canal. 
     FIG. 5 shows a second embodiment of a sealing body. The sealing body  25  comprises a central tube  60 , on which three shells  61 ,  62  and  63  are provided. The tube  60  bounds a channel  65 , which is widened in a spherical shape at the distal end part. The channel part widened in a spherical shape is bounded by an end wall  66  with an end edge part  67  bent inwards in the radial direction. The end edge part  67  will deform elastically in the axial direction under an axial pressure load. The end wall  66  further comprises a central part  68 , to which the first shell  61  directly connects. The first shell  61  and the end wall  66  have a lower thickness than the thickness of the wall of the tube  60 . If the end edge part  67  deforms, the first shell  61  can then deform outwards slightly in the radial direction. 
     FIG. 13 shows a third embodiment of a sealing body. The sealing body  70  comprises a central tube  71 , on which two shells  72  and  73  are provided. The tube  71  bounds a channel  75 . The front part of the channel  75  opens out into an open chamber  76 . The open chamber  76  is bounded by an end wall  77  with an end edge part  78  bent inwards in the radial direction. The end wall  77  has a smaller thickness than the tube  71 . The end wall  77  further comprises a central part  79  with a substantially constant radial measurement. This ensures that during insertion into an auditory canal the front part of the sealing body is being less flattened than is the case with the embodiment in FIG. 1, making the insertion slightly easier. The end edge part  78  can still deform elastically in a simple manner in the axial direction under an axial pressure load. 
     Thus the invention provides sealing bodies which feel comfortable in the ear without in the process exerting too great pressure on certain points in the auditory canal. The shape is suitable for universal use. Surprisingly, it has been found in practice that the muffling characteristics of the sealing body are very consistent with the muffling characteristics of the muffling device according to the invention. This is probably due to the widened distal end part of the channel which is partly bounded by the end edge part of elastically deformable material bent inwards in the radial direction. However, the sealing body according to the invention can also be used in combination with other muffling devices. 
     In this way, the invention provides a hearing protector with a simple stepwise adjustable muffling device in combination with a universal sealing body which is extremely comfortable to wear, while the muffling characteristics of the hearing protector as a whole meet both the requirements and the statutory standards.