Acoustically transparent ingress barrier

Abstract

The present invention relates to an ingress barrier assembly comprising a frame defining a sound opening for the passage of sound and an, essentially acoustically transparent, ingress barrier membrane covering the sound opening, wherein the ingress barrier membrane has a Young's modulus of less than 0.1 GPa, and is configured such that it has a slackequivalent of more than 0.1 mm and a tension point of less than 0.2 kPa. The present invention further relates to a method for manufacturing the ingress barrier assembly; to use of an ingress barrier membrane in an ingress barrier assembly; to a dome incorporating the ingress barrier assembly; and to a device or device part comprising the ingress barrier assembly.

Description

[0001] ACOUSTICALLY TRANSPARENT INGRESS BARRIER

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an essentially acoustically transparent ingress barrier; and to domes and in ear-acoustic devices or parts thereof, such as acoustic transducers, comprising the acoustically transparent ingress barrier. In particular, the present invention relates to an ingress barrier assembly; to a method for manufacturing the ingress barrier assembly; to use of an ingress barrier membrane in an ingress barrier assembly; to a dome incorporating the ingress barrier assembly; and to a device or device part comprising the ingress barrier assembly.

[0004] BACKGROUND OF THE INVENTION

[0005] Acoustic transducers as used herein are microphones such as electret microphones, microelectromechanical system (MEMS) microphones; receivers (speakers) such as balanced armature receivers, moving coil receivers and MEMS speakers; and vibration sensors capable of capturing or transmitting vibrations in the audible to near audible sound range. In particular, acoustic transducers may operate at 1 Hz to 100 kHz, preferably 5 Hz to 60 kHz, more preferably 20 Hz to 20 kHz.

[0006] Acoustically transparent as used herein means that, as compared with a system wherein an acoustic transducer is used without ingress barrier, the ingress barrier provides a maximum Sound Pressure Level (SPL) decrease at 1 kHz of at most 6 dB, preferably at most 3 dB and even more preferably at most 2 dB and a maximum increased Total Harmonic Distortion (THD) of not more than 3%. Measurement of THD and SPL is set out in more detail in example 7 in the description below.

[0007] EP 0 835 042 A2 describes a protective barrier (membrane) for the sound inlet and / or sound outlet of earbuds for hearing devices. The sound outlet and / or inlet is closed off with a nonporous, inert, thin membrane that is capable of sound transmission, in particular a thin (less than 0.01 mm thickness) titanium membrane. The titanium metal membrane moves with applied sound pressure levels and in this way transmits the sound. According to EP 0 835 042 A2 the titanium membrane is capable of transmitting sound without significant gain loss and without disturbing distortion. The titanium membrane suitably has a dual function, also as an acoustic filter and / or an acoustic lens. Thus, this membrane leaves much to be desired in terms of acoustic transparency.

[0008] The background section of US 7,751,579 B2, originally filed more than 2 decades ago, summarizes some 4 decades of research prior to that, to find an acceptable acoustically transparent ingress barrier. US 7,751,579 B2 itself relates to an acoustically transparent ingress barrier for audio transducers. The barrier preferably comprises a very thin film of a polyethylene blend comprising an organometallic complex such as hexane or metalocine, having a thickness of less than 7.5 pm, for example less than 3.75 pm, making it fragile and prone to rupture when cleaning. Further, whilst it was essentially acoustically transparent, with respect to a 'C-Barriertm' product manufactured in accordance with US 7,751,579 B2 and marketed by Sonion for a while, at some frequencies, sound pressure levels and environments, crackling and rattling noises could be experienced by a number of users, especially when the in-ear piece containing the C-Barriertmmoved in-ear due to e.g. chewing or other causes.

[0009] US2019 / 0208303 describes an ear tip with an ingress barrier for an acoustic device. The ingress barrier may be porous or non-porous. Silicone is described as an example of a non- porous barrier material. The barrier is described as acoustically transmissive. It would be desirable to provide an ingress barrier that is essentially acoustically transparent rather than merely transmissive.

[0010] US 10,284,974 B2 relates to an acoustically transparent barrier layer to seal audio transducers. The barrier layer is a thin, low-density layer that is arranged around or on an exposed or open surface of an acoustic sensor. Environmental changes, e.g. differences in temperature or pressure, are accommodated without introducing tension in the barrier layer neutral rest position, for example by pressure balancing mechanisms, such as a pressureequalizing leak path or leak passages in a porous plastic frame capturing the barrier layer etc. Where the ratio of internal volume of sealed cavity to barrier layer surface area is small, it may be sufficient not to have a pressure equalizing path. This translates into a relatively large barrier layer surface area. Whilst this may be advantageous, a large barrier layer surface area may reduce the utility of such barrier layer in receiver in canal designs as the fit rate (i.e. the percentage of adults having the ability to fit a receiver in canal configuration in their ear canal) may reduce to unacceptable low levels. US 10,284,974 B2 does not disclose a thickness of the acoustically transparent barrier layer, except that a heat bonding process for manufacturing is not suitable as acoustic transparency requires very thin film. The barrier layer should further be designed to move without introducing excessive tension.

[0011] US 10,284,974 B2 lists broad categories of barrier layer compositions but does not disclose specific barrier layer compositions other than aluminum or graphene. Thus, the barrier layer may be a thermoplastic material, a thermoset material, an elastomeric material, or blends thereof, optionally coated with other layers such as a metallic layer; may be a metal layer, like aluminum, or graphene or, undefined, other materials.

[0012] US 11,330,382 B2 relates to an acoustical protector for audio devices, which acoustical protector is designed to allow sound to pass through it with minimal distortion, while protecting the audio transducer from foreign material such as dust, magnetized dust, sand and other heavier particles, water, water mixed with particles (i.e. mud and 'grime'), skin cells, oils and ear wax (cerumen). Whilst many of these materials may be partly kept out by screens and porous meshes, these screens and porous meshes invariably let some undesirable foreign material through. The acoustical protector comprises a, preferably rigid, dome-shaped sound radiating element that is allowed to move axially, transmitting sound waves from a sound generating transducer to the eardrum, by means of a flexible bellows. It is important to make the rigid dome as large as possible to limit non-linear displacement behaviour. Non-linear displacement behaviour leads to acoustic distortions. Another reason for the large size of the dome is to lower the acoustical impedance. The acoustical impedance is described as proportional to 1 / d2, where d is the diameter of the dome. According to US 11,330,382 B2 a dome may be constructed from silicone having a wall thickness of from 1,25 centimeter to 25 micrometer, but preferably the dome is made of a stiff thin material such as Kaptontm(polyimide) or PET. The protector device is said to be preferably 3-8 mm in length. A length of a protector device of 3-8 mm may not be acceptable in practice as users of hearing devices require such hearing devices to be as invisible as possible. Adding 3-8 mm to a typical length of a receiver for use in an ear canal, 3-5 mm, may not be acceptable to the end-user. Also, the axially moving rigid dome, when inserted into an ear canal, may result in the dome frequently hitting a wall of the ear canal, leading to discomfort for the end-user. In addition, if a dome were to hit a wall of the ear canal of a user, this may lead to non-linear behaviour, the bellows, being flexible, and result in non-linear behaviour and acoustic distortion. Thus, the design of US 11,330,382 B2 may leave much to be desired for the end-user in terms of visibility, performance and comfort.

[0013] Phonak AG markets wax filters under the trade name "Phonak SmartGuard Wax Protector", which are claimed to be acoustically transparent and made of a thin, highly elastic polymer membrane which is laser-welded to a rigid ring that is to be positioned at a wax filter position commonly incorporated in a hearing device near the sound output of the hearing device. Further analysis of several of these commercially available products revealed inconsistency in acoustic transparency performance and a too high THD. The elastic polymer membrane was analysed to be a thermoplastic polyurethane.

[0014] EP1562400 in the name of Phonak AG describes a wax filter element comprising a highly elastic membrane having a thickness of at most 30 pm, preferably at most 20 pm, such as 15 pm. The membrane is suitably affixed to a ring and having a diameter of about 3 mm, to allow a good fit rate, fitting in the ear canal of most adults. The elastomeric membrane may be selected from a wide range of thermoset and thermoplastic elastomers. As reported in Figure 3 of EP1562400, use of the elastic membrane results in a sound pressure level drop of 2dB across the entire frequency response for the receiver in question. Despite many decades of research into this area, a highly effective, acoustically transparent ingress barrier that is capable of protecting an acoustic transducer, in particular a sound path and opening of an acoustic transducer from solid, liquid and gaseous debris, does not introduce sound artefacts like crackling or rattling noises, is not fragile, can easily be cleaned etc., is, to date, not available on the market. The failure rates of e.g. receivers in the ear canal of a person, such as in Tn the Ear' hearing devices, caused by accumulation of debris, such as cerumen, in the receiver is currently thought to be more than 50 percent. It will be appreciated that from a patient care perspective, cost of repair and replacement, overall healthcare costs and from an environment and sustainability perspective, it would be highly desirable, meet a long-felt need, if such an acoustically transparent ingress barrier could be found.

[0015] As described herein in more detail below, the present inventors have now surprisingly found such an acoustically transparent ingress barrier.

[0016] DESCRIPTION OF THE INVENTION

[0017] It would be desirable to provide for an ingress barrier assembly that overcomes one or more of the drawbacks of prior art ingress barrier assemblies. In particular, it would be desirable to provide for an ingress barrier assembly that is essentially acoustically transparent, and which is capable of protecting an acoustic device against ingress of contaminants such as dust, wax, cerumen, moisture and water.

[0018] It may therefore be seen as an object of embodiments of the present invention to provide for an ingress barrier assembly that combines one or more, preferably all, of these desired advantages.

[0019] Accordingly, the present invention provides according to a first aspect, an ingress barrier assembly in accordance with claim 1. Thus, according to a first aspect, the present invention provides an ingress barrier assembly comprising a frame defining a sound opening for the passage of sound and an ingress barrier membrane covering the sound opening, wherein the ingress barrier membrane has a Young's modulus of less than 0.1 GPa, and is configured such that the ingress barrier membrane has a slackeqUivaient of more than 0.1 mm and a tension point of less than 0.2 kPa.

[0020] The tension point is defined as the minimum amount of DC pressure needed to fully tension an ingress barrier membrane attached to a rigid ring frame. Thus, the minimum DC pressure is sufficient to bring the ingress barrier membrane in a tensioned position substantially without stretching the ingress barrier membrane, i.e. substantially without elastically deforming the ingress barrier membrane. The detailed method to measure the tension point is set out below with reference to figures 12 and 13.

[0021] Slack is defined as the maximum displacement in mm of an ingress barrier membrane of 2.5 mm diameter attached to a rigid ring frame, in the absence of elastic deformation. The detailed method to measure slack is set out below with reference to figures 12 and 13.

[0022] SlackeqUivaient is defined as the maximum displacement in mm of an ingress barrier membrane having a diameter in the range from 1 to 20 mm, attached to a rigid frame, in the absence of elastic deformation, as measured using the detailed method to measure slack as set out below with reference to figures 12 and 13, and recalculated to an equivalent slack for an ingress barrier membrane of 2.5 mm diameter attached to a rigid ring frame, in the absence of elastic deformation. The formula for recalculating to an equivalent slack for an ingress barrier membrane of 2.5 mm diameter attached to a rigid ring frame is as follows:

[0023] Thus, for an ingress barrier membrane having a diameter of 2.5 mm attached to a rigid ring frame, slack will equal slackeqUiVaient. Diameter as used herein is the effective diameter, i.e. the diameter effectively used as ingress barrier. Thus, the ingress barrier membrane may have a larger diameter but upon attachment to a rigid ring, and placing inside and closing a sound opening, the effective diameter of the ingress barrier membrane equals the inner diameter of the rigid ring. Where the ingress barrier assembly according to the invention is not an essentially circular shape, but for example oval or hexagon shaped, the displacement is measured as described herein, and shortest diameter is chosen to calculate slackeqUiVaient.

[0024] The ingress barrier membrane in the assembly according to the invention is essentially acoustically transparent when used in the sound opening of a dome to be positioned in the ear canal of a person. A diameter of about 2.5 mm is advantageous as this fits the ear canals of most persons. It may be desired in certain configurations and embodiments to use an ingress barrier membrane that is smaller than 2.5 mm diameter and it may also be desired in certain configurations and embodiments that an ingress barrier membrane is used having a larger diameter. Typically, the ingress barrier membrane diameter may range from 1 to 20 mm. At a diameter below 1 mm, acoustic transparency may be more difficult to achieve and manufacture of an ingress barrier assembly comprising such ingress barrier membrane becomes more difficult. At a diameter above 20 mm, use of the ingress barrier assembly in or near the ear canal, such as in the concha, becomes more difficult. At the same time, a carefully defined displacement, slack, is less critical in order to achieve an acoustically transparent ingress barrier assembly at an ingress barrier membrane diameter above 20 mm. Preferably, the diameter of the ingress barrier membrane is at least 1.5 mm, more preferably at least 2 mm. Typically the ingress barrier membrane diameter is not more than 10 mm, preferably not more than 5 mm, even more preferably not more than 3.5 mm.

[0025] The present inventors have found that the amount of displacement required to achieve an acoustically transparent ingress barrier assembly according to the invention varies with the diameter of the ingress barrier membrane. The slackeqUivaient formula given above may be used to calculate the minimum amount of displacement needed at a given ingress barrier membrane diameter. Thus, the equation above can be rewritten as follows:

[0026] For an ingress barrier membrane having a diameter of 1.5 mm the minimum displacement (minimum 'slack') should therefore be: 0.1 x 3.14 x (1.25)21 3.14 x (0.75)2= 0.277 mm.

[0027] For an ingress barrier membrane having a diameter of 3.5 mm the minimum displacement (minimum 'slack') should therefore be 0.1 x 3.14 x (1.25)2 / 3.14 x (1.75)2= 0.051 mm.

[0028] Preferably, the ingress barrier membrane has a Young's modulus of less than 0.05 GPa, such as less than 0.04 GPa. Preferably, the ingress barrier membrane has a Young's modulus of more than 0.0005 GPa, in particular more than 0.001 GPa, such as more than 0.01 GPa.

[0029] The ingress barrier membrane may be an elastomeric material such as a thermoplastic elastomer or a thermoset elastomer. Typically, the ingress barrier membrane may comprise, or consist essentially of, a polymer material selected from the group of butyl rubber, polyisoprene rubber, ethylene vinyl acetate, natural rubber, polychloroprene, polyurethane elastomer, polysiloxane, styrene (optionally hydrogenated) alkylene block copolymer and other thermoplastic elastomers. It is also possible that a combination of two or more polymers is used. For example, where a polymer is used that is not biocompatible, it may be preferred to apply a thin layer of a biocompatible polymer on the side of the ingress barrier membrane that in use is intended to be in contact with, or close to, the skin of a person, such as the ear canal of a person.

[0030] Preferably, the ingress barrier membrane comprises a (cured) polysiloxane (silicone) having a Shore A hardness in the range of from 1 to 50, more preferably 3 to 45, even more preferably 6 to 35, in particular 7 to 25. An example of a preferred polysiloxane includes a cured liquid silicone rubber (LSR). Another preferred polysiloxane is room-temperature vulcanisable polysiloxane (RTV). Both LSR and RTV typically use platinum based curing agents to cure the polysiloxane. The ingress barrier membrane typically has a thickness of less than 50pm, preferably less than 40 pm, more preferably less than 30 pm, even more preferably less than 25 pm, such as less than 20 pm. If the ingress barrier becomes too thin, it may rupture easily and becomes difficult to handle. The ingress barrier membrane typically has a thickness of more than 3 pm, preferably more than 4 pm, more preferably more than 5 pm.

[0031] The ingress barrier membrane is typically used in the ear canal of a person. Therefore, it is desired that the ingress barrier membrane has dimensions that fit the ear canal of a person, preferably even smaller to minimize the risk that movement of the ear canal, for example by a person chewing, influences the ingress barrier membrane in undesired ways. Preferably, the ingress barrier membrane is mechanically disconnected from the ear canal. Ways to achieve this are discussed in more detail below. Preferably, the ingress barrier membrane is circular. According to a further preferred embodiment, the ingress barrier membrane has a diameter of not more than 4.5 mm, preferably not more than 4 mm, even more preferably not more than 3.5 mm, such as 2.5 mm. The ingress barrier assembly typically has a diameter of at least 1 mm, preferably at least 1.5 mm, more preferably at least 2 mm, even more preferably at least 2.3 mm.

[0032] The ingress barrier assembly is configured such that the ingress barrier membrane has a slackeqUivaient of more than 0.1 mm and a tension point of less than 0.2 kPa.

[0033] Preferably, the ingress barrier assembly is configured such that the ingress barrier membrane has a slackequivalent of more than 0.15 mm. Preferably, the ingress barrier assembly is configured such that the ingress barrier membrane has a slackequivaient of less than 0.35 mm.

[0034] The ingress barrier membrane may itself be formed such that the slackequivaient is as desired, or the frame of the assembly may cause the slackequivaient in the ingress barrier membrane to form, such as by compression of the diameter of the ingress barrier membrane. In that latter situation, the ingress barrier membrane itself, prior to incorporation into the ingress barrier assembly may have substantially no slackequivaient. Accordingly, the configuration of the ingress barrier assembly to cause a defined slackequivaient in the ingress barrier membrane may involve configuration of the frame, or the ingress barrier membrane or both. Examples of these embodiments are discussed in more detail below.

[0035] Preferably, the ingress barrier membrane is configured so that the tension point is less than 0.15 kPa. Preferably, the ingress barrier membrane is configured so that the tension point is more than 0.001 kPa, even more preferably more than 0.01 kPa, such as more than 0.05 kPa.

[0036] The frame defines the sound opening. 1. Typically, the frame is a rigid frame, wherein the rigid frame preferably has a Young's modulus of at least 0.1 GPa. In some embodiments, the rigid frame is a rigid ring. In one embodiment, the ingress barrier membrane is positioned on or in a rubber ring, wherein the rubber ring is enclosed by the rigid ring, the rubber ring having an outer diameter of at least 0.001 mm more than the internal diameter of the rigid ring.

[0037] Preferably, the sound opening defined by the frame is circular. According to one embodiment of the ingress barrier assembly according to the invention, the frame is a rigid frame. The rigid frame may be made from a polymeric material such as a polymer having a Young's modulus of at least 0.2 GPa, preferably at least 0.5 GPa, more preferably at least 1 GPa, such as more than 2 GPa. The rigid frame may also be made from a ceramic material or a metal or metal alloy like stainless steel, titanium and the like. Preferably a biocompatible polymer is used or a non-allergenic metal like titanium.

[0038] It may be that the frame is a part of a device or device housing. However, for ease of manufacture and in order to be able to replace the ingress barrier assembly, it is preferred that the frame is a rigid ring. The ingress barrier membrane may be connected to the rigid ring, for example by means of an adhesive or by overmoulding. According to a preferred embodiment, the ingress barrier membrane is mounted on or in a rubber ring, wherein the rubber ring is enclosed by the rigid ring, the rubber ring having an outer diameter of at least 0.005 mm, preferably at least 0.01 mm more than the internal diameter of the rigid ring. Preferably, the rubber ring has an outer diameter not more than 0.5 mm more, more preferably not more than 0.1 mm more, than the internal diameter of the rigid ring.

[0039] According to another embodiment, the ingress barrier membrane with a defined slackeqUiVaient may be directly attached to the rigid frame such as the rigid ring. One way to achieve this is by moulding or adhering a curable polymer ingress barrier membrane precursor on or in the rigid frame, partly curing the curable polymer membrane, applying pressure to the partly cured polymer membrane in a direction transversal to the diameter of the partly-cured polymer membrane and continuing curing the polymer membrane until substantially complete, followed by a release of the pressure. The pressure may for example be applied by a blunt protrusion or by applying air pressure, as discussed in more detail below. A curable silicone polymer, such as a curable liquid silicone polymer, is preferably used in this method.

[0040] The present invention provides according to a second aspect, an ingress barrier assembly comprising a frame defining a sound opening for the passage of sound and an ingress barrier membrane covering the sound opening, wherein the ingress barrier membrane is a polysiloxane having a Shore A hardness in the range from 5 to 35, the membrane has a thickness of between 5 and 20 pm, preferably 7 to 13 pm, and a diameter in the range from 2 to 3.5 mm, and is configured such that the ingress barrier membrane has a slackeqUivaient of more than 0.1 mm.

[0041] The present invention provides according to a third aspect, use of an ingress barrier membrane mounted on or in a rubber ring, wherein the ingress barrier membrane has a Young's modulus of less than 0.1 GPa and substantially no slackeqUiVaient, wherein the use of such membrane is in an ingress barrier assembly according to the invention as described above, comprising a rigid ring, wherein the rubber ring is enclosed by the rigid ring, the rubber ring having an outer diameter of at least 0.005 mm more, such as at least 0.01 mm more (and preferably not more than 0.5 mm more) than the internal diameter of the rigid ring. Positioning the ingress barrier membrane comprising the rubber ring inside the rigid ring causes the introduction of slackeqUivaient in the ingress barrier membrane.

[0042] The present invention provides according to a fourth aspect, a method for making an ingress barrier assembly as described above comprising the steps of (1) moulding a membrane from a thermoset elastomer such as a polysiloxane: (2) curing the membrane until the membrane is substantially demouldable and (3) affixing the membrane to an ingress barrier frame; or (1) moulding a membrane and ingress barrier frame together from a thermoset elastomer such as a polysiloxane: (2) curing the membrane and ingress barrier frame assembly until the membrane and ingress barrier frame assembly is substantially demouldable; followed by applying excess pressure to one side of the membrane, and continuing curing whilst continuing to apply pressure until curing is essentially complete, releasing pressure and yielding the ingress barrier assembly.

[0043] The present invention provides according to a fifth aspect, a dome comprising a dome sound opening for the passage of sound and an ingress barrier assembly as described herein, wherein the frame is at least that part of the dome surrounding the dome sound opening and wherein the ingress barrier membrane covers the dome sound opening. The ingress barrier assembly may cover the dome sound opening or sound path on the outside of the dome or inserted in the sound opening or sound path at some distance from the outside of the dome. In one embodiment, the ingress barrier membrane comprises a curable polymer membrane, obtainable by molding a dome with a curable polymer membrane, partly curing the polymer membrane, applying pressure to the polymer membrane and continuing curing the polymer membrane, followed by releasing the pressure. In a further embodiment, the dome comprises a flexible circumferential member arranged circumferentially around the dome sound opening, wherein the flexible circumferential member is configured to mechanically disconnect from at least the part of the dome sound opening comprising the ingress barrier membrane.

[0044] According to a preferred embodiment, the dome may comprise:

[0045] - a circumferential member arranged circumferentially and extending in the longitudinal direction between a front end and a rear end, wherein a sound opening is arranged at the front end, the sound opening being configured for passage of sound,

[0046] - an extension terminating in a free end and extending in the longitudinal direction from an inner surface of the circumferential member, the extension forming a sound path, wherein the ingress barrier assembly is positioned in and covers the sound path. The dome may be a so-called 2K-dome. In this embodiment, the extension is formed by a first material and the circumferential member is formed by a second material, the second material being more flexible than the first material. Suitable first and second materials have been described in more detail in international application publication No. WO2024079173, incorporated herein by reference.

[0047] Alternatively, the extension and the circumferential member may be made of the same material, such as a polysiloxane. An advantage of positioning an ingress barrier assembly in the extension is that the frame and membrane may be made of the same material as the dome, whilst the risk of unwanted interferences from movement of the circumferential member in the ear canal of a person may be reduced or avoided all together.

[0048] Preferably, the ingress barrier membrane comprises a curable elastomeric polymer membrane, and the ingress barrier assembly in the dome is obtainable by molding a dome with a curable elastomeric polymer membrane, partly curing the elastomeric polymer membrane, applying pressure to the elastomeric polymer membrane and continuing curing the elastomeric polymer membrane, followed by releasing the pressure.

[0049] The dome may be custom-made to fit the ear canal of a person. In such case, the dome is preferably made of a rigid polymer, such as polymers having a Young's modulus of more than 0.1 GPa, typically more than 0.2 GPa, or a Shore A hardness of more than 60. Alternatively, the dome may be made of metal, such as titanium. The dome may thus suitably function as the frame in the ingress barrier assembly.

[0050] According to another embodiment, the dome comprises a flexible circumferential member arranged circumferentially around the dome sound opening. In this case, movement of the flexible circumferential member in the ear canal of a person is preferably isolated from movement of the ingress barrier membrane due to acoustic pressure caused by sound waves. According to a preferred embodiment, the flexible circumferential member is configured to mechanically disconnect from at least the part of the dome sound opening comprising the ingress barrier membrane. It will be appreciated that this may be achieved in a number of ways, including providing an ingress barrier assembly with a rigid ring around the ingress barrier membrane; and / or by providing a slit between the part of the dome comprising the ingress barrier assembly and the circumferential member. These embodiments have been discussed in more detail in Figures 6 and 7 described below.

[0051] The present invention provides according to a sixth aspect, a device or device part, in particular an acoustic device or device part, comprising a device sound opening or sound path for the passage of sound and an ingress barrier assembly as described herein, wherein at least the ingress barrier membrane is configured to cover the device sound opening or sound path. The ingress barrier assembly may cover the device sound opening or sound path on the outside of the device or inserted in the sound opening or sound path at some distance from the outside of the device.

[0052] In principle any device that is at risk of ingress of wax, cerumen, moisture, water, dust and the like into the device may benefit from an ingress barrier assembly that is essentially acoustically transparent but at the same time prevents ingress of wax, cerumen, moisture, water, dust and the like into the device, and accordingly, preferably comprises the ingress barrier assembly according to the invention. Where the ingress barrier assembly is to be used in or on a device, it may be preferred that the frame is provided with an engagement structure or engagement structures to releasably attach the ingress barrier assembly to the device (part).

[0053] Examples of devices or device parts that preferably comprise the ingress barrier assembly according to the invention include transducers, such as microphones, speakers (receivers), wax filters, transducers in canal assemblies, including receiver in canal assemblies (RIC) and microphone and receiver in canal assemblies (MRIC), earbuds, hearables, and hearing devices.

[0054] In general, the various aspects of the present invention may be combined and coupled in any way possible within the scope of the invention. These and other aspects, features and / or advantages of the present invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0055] BRIEF DESCRIPTION OF THE FIGURES

[0056] In the following, example embodiments will be described with reference to the figures, wherein:

[0057] Figure 1 illustrates a first method to introduce slackeqUiVaient in an ingress barrier according to the invention.

[0058] Figure 2 illustrates a second method to introduce slackeqUiVaient in an ingress barrier according to the invention.

[0059] Figure 3 illustrates a third method to introduce slackeqUiVaient in an ingress barrier according to the invention.

[0060] Figure 4 illustrates a method of incorporating an ingress barrier assembly into a dome.

[0061] Figure 5 illustrates a further method to introduce slackeqUiVaient in an ingress barrier according to the invention, whereby the ingress barrier is part of a dome. Figure 6 illustrates a dome comprising an ingress barrier assembly according to the invention.

[0062] Figure 7 illustrates a dome comprising an ingress barrier according to the invention whereby the skirt, circumferential member, of the dome is decoupled from the ingress barrier.

[0063] Figures 8, 9 and 10 show results of measurement of acoustical properties of the ingress barrier assembly according to the invention, as compared with no barrier.

[0064] Figure 11 shows results of measurement of acoustical properties of a comparative ingress barrier assembly not according to the invention.

[0065] Figure 12 depicts an analytical method for determining slack.

[0066] Figure 13 shows results of a slack measurement

[0067] Figure 14 depicts an acoustical measurement setup for SPL and THD measurements

[0068] Figure 15 illustrates various designs of the frame part of the ingress barrier assembly.

[0069] DETAILED DESCRIPTION OF THE FIGURES

[0070] Figure 1 illustrates a first method to introduce slackeqUiVaient in an ingress barrier according to the invention. The method involves molding a membrane comprising a curable (thermoset) elastomer, such as a polysiloxane, curing and demoulding when curing is not yet complete, for example approximately 50% complete (not shown), stretching the de-moulded membrane (1) by applying a force perpendicular to the plane as indicated by the arrow (5, 6) in Figure 1(a), continuing curing whilst continuing to apply the force until curing is substantially complete and allowing the membrane (4) to relax as shown in Figure 1(b). The de-moulded membrane (1) is typically temporarily or permanently affixed to or pressed against a ring (2), for example a rigid metal or plastic ring, which is positioned over a blunt protrusion (3). In one embodiment as shown in Figure 1(a), the blunt protrusion may move upward to push the membrane (1) to a desired level of stretch. The force applied is indicated by arrow 5 in Figure 1(a). Alternatively, a demoulded membrane (1) may be positioned on a surface such as a table (not shown) containing fixed protrusions 3. The ring (2) may be pressed downward onto the table by applying a force indicated by arrows 6. It will be appreciated that also a combination of ferees indicated by arrows 5 and 6 may be applied. The membrane (4) having a defined slackeqUiVaient and Young's modulus may be used as an ingress barrier membrane according to the invention, as further exemplified in Example 2 and 4. Further it will be appreciated that the blunt protrusion 3 may be replaced by for example applying fluid (liquid or gas, such as air) pressure through openings (not shown) in a table or other suitable flat surface on which the film is positioned during manufacture of ingress barrier assemblies according to the invention.

[0071] A further variation to the method depicted in Figure 1 involves use of a thermoplastic elastomer. A thin elastomer film is produced by means known in the art such as injection moulding, extrusion, calendaring and solution deposition. The film is positioned on top of a table containing protrusions 3 and rings 2 are affixed, for example by welding to the film and the film is then cut around rings 2 to produce ingress barrier assemblies having a defined slackeqUivaient. It will be appreciated that the same method may be used in case of thermoset elastomers. In that case, a curing step needs to be carried out. In this variation of the method according to Figure 1, it is not necessary to cure until the film is partly cured but, if desired, the film may be cured until curing is substantially complete before applying the rings 2. Also in this embodiment, the blunt protrusion 3 may be replaced by for example applying fluid (liquid or gas, such as air) pressure through openings (not shown) in a table or other suitable flat surface on which the film is positioned during manufacture of ingress barrier assemblies according to the invention.

[0072] Figure 2 illustrates a second method to introduce slackeqUivaient in an ingress barrier according to the invention. Figure 2(a) depicts an elastomeric membrane 7 containing substantially no slackeqUivaient. A flexible ring with a diameter of 2-4 mm, preferably 2.2. - 2.8 mm, such as about 2.5 mm, may be affixed to the elastomeric membrane (not shown). An ingress barrier assembly 8 having a defined slackeqUivaient may be produced using force 9 to compress the flexible ring, and thereby the elastomeric membrane affixed to the flexible ring, to produce an ingress barrier assembly having a defined slackeqUiVaient. The flexible ring is preferably compressed substantially equally in all radial directions. This may be achieved by positioning the flexible ring in a rigid ring having an inner diameter which is smaller than the outer diameter of the flexible ring. Preferably, the rigid ring has an inner diameter which is between 0.1-10% smaller than the outer diameter of the flexible ring, more preferably 0.2- 5% smaller, even more preferably 0.3 to 2% smaller. An embodiment where an elastomeric membrane containing substantially no slackeqUivaient, affixed onto a flexible ring is positioned in a rigid ring incorporated in a dome, is depicted in Figure 4.

[0073] Figure 3 illustrates a third method to introduce slackeqUivaient in an ingress barrier according to the invention. As depicted in Figure 3(a), a metal cast 10 having a preformed curvature 11 is used. A liquid elastomeric solution, such as a liquid polysiloxane solution, is applied on the metal cast 10 with the preformed curvature 11 and cured (in case the elastomer requires curing). The ingress barrier 12 with defined slackeqUivaient is then removed from the metal cast 10. This method is further exemplified in Example 1.

[0074] Figure 4 illustrates an ingress barrier assembly 29, 27, 25 according to the invention incorporated into dome 20. Figure 4(a) depicts a dome 20, comprising a flexible circumferential member 21 (skirt) and a cylindrical stem 26 positioned inside the flexible circumferential member 21, which cylindrical stem 26 (also referred to as extension) is configured for releasably affixing dome 20 onto nozzle 23 of transducer housing 22. Sound opening 30 (figure 4(b)) of dome 20 is in acoustic communication with sound opening 24 of nozzle 23. Transducer housing 22 typically contains a receiver (not shown). If desired, also a microphone may be present in transducer housing 22. Compression ring 25, typically a metal ring, such as a titanium ring, is positioned in sound opening 30 of dome 20. In the embodiment shown in figure 4, compression ring 25 is an U-shaped metal ring. It will be appreciated that also other shapes are possible and for example for ease of manufacturing an L-shaped compression ring may be used. In case an L-shaped compression ring is used, preferably the part of the L with the smallest internal diameter is facing sound opening 30.

[0075] The compression ring 25 is capable of accommodating flexible ring 27 with membrane 28. In the embodiment shown in Figure 4(a), membrane 28 has no defined slackeqUiVaient and the outer diameter of flexible ring 27 is 1% larger than the inner diameter of compression ring 25. The inner diameter of compression ring 25 is that part of compression ring 25 that functions to compress flexible ring 27 in radial direction. Thus, in case the compression ring part 25 is U-shaped or L-shaped, the legs of the U and the horizontal leg of the L are primarily configured to keep the flexible ring 27 in position, not to compress flexible ring 27 in radial direction. As shown in Figure 4(b), positioning flexible ring 27 and membrane 28 into compression ring 25 causes the membrane 28 to deform and an ingress barrier assembly with defined slackeqUiVaient 29 is formed. It will be appreciated that instead of using metal for compression ring 25, another suitable material may be used that is preferably biocompatible; is able to keep membrane 28 in a deformed position and at the same time does not deform when for example dome 20 is inserted in the ear canal of a person. In addition, compression ring 25 should be affixed in dome 20 such that compression ring 25 and / or ingress barrier 27, 29 do not become separated from the dome whilst in use in the ear canal of a person. For example, metal may be replaced by a hard plastic, such as polyethylene or polypropylene.

[0076] Figure 5 illustrates a further method to introduce slackeqUiVaient in an ingress barrier 36 according to the invention, whereby the ingress barrier is part of a dome 37. Figure 5(a) depicts a dome 37, comprising a flexible circumferential member 31 (skirt) and a cylindrical stem (extension) 32 positioned inside the flexible circumferential member 31, which cylindrical stem 32 is configured for releasably affixing dome 37 onto a transducer housing (not shown), typically a nozzle of a transducer housing. Membrane 33 covers the sound opening of dome 37. Membrane 33 in Figure 5(a) is only partly cured. Membrane 33 is stretched to stretched membrane 34 as shown in Figure 5(b) by means of a force 35 applied to the membrane. The force may be air blown through the cylindrical stem 32, or a blunt instrument (not shown) may be used to stretch membrane 33 to stretched membrane 34. Upon removal of feree 35, and when curing is substantially complete, an ingress barrier membrane 36 with defined slackeqUiVaient is formed as shown in Figure 5(c). When dome 37 is inserted in the ear canal of a person, flexible circumferential member 31 may move and deform when the person speaks, chews or makes other movements that influence the precise shape of the ear canal. According to the present invention, the ingress barrier member 36 is able to move substantially independently of the movement of flexible circumferential member 31. Two ways to achieve this are depicted in Figures 6 and 7.

[0077] Figure 6 depicts a dome 40 comprising a rigid ring 41 with ingress barrier membrane 42 with defined slackeqUiVaient. The rigid ring 41 functions to isolate ingress barrier membrane 42 from movement of the dome 40 itself in particular the flexible circumferential member 43.

[0078] Figure 7 depicts a dome 44 comprising a flexible circumferential member (skirt) 46 and cylindrical stem 45 configured for releasably affixing dome 44 onto nozzle 48 of transducer housing 47. Ingress barrier 50 according to the invention is decoupled from flexible circumferential member 46 by means of slit 49.

[0079] Referring to figures 6 and 7, it will be appreciated that the two embodiments 41, 49 to decouple the ingress barrier membrane 42, 50 may be combined. Accordingly, a dome may be provided with a slit 49 and the ingress barrier may be positioned in a rigid ring 41 affixed to the sound opening of dome 40,44. The dome depicted in Figure 4 may also be provided with a slit (not shown) to further decouple ingress barrier assembly 25, 27, 29 from flexible circumferential member 21 of dome 20.

[0080] According to yet another embodiment, dome 20, 37, 40, 44 is custom-made to fit the ear canal of a person. Custom-made domes, such as custom shells, typically are made of hard plastic or metal, such as titanium metal. In this case, compression ring 25 as depicted in Figure 4 may be in the form of a U-shaped or L-shaped groove or indentation.

[0081] Figures 8 to 11 will now be described with reference to the following Examples. In each of the examples, slack (and where a diameter different than 2.5 mm was used, slackeqUiVaient ) was determined according to the method set out in more detail below, with reference to Figures 12 and 13. describes an experiment in which an ingress barrier membrane according to the present invention was prepared by adding a defined slackeqUiVaient during manufacture of the ingress barrier membrane.

[0082] A metal cast having a preformed curvature as depicted in Figure 3(a) was used to produce an ingress barrier membrane. A liquid polysiloxane solution being a commercially available room temperature vulcanization polysiloxane variant using a platinum based curing agent, was applied on the metal cast. The metal cast was kept at a temperature of 80°C and the polysiloxane was allowed to cure for lhr. The cured polysiloxane ingress barrier membrane had a diameter of 2.5 mm, an average thickness of 10 pm, a Young's modulus of 0.3MPa, a Shore A Hardness of 8, a slack (and, as the diameter was 2.5 mm, slackeqUiVaient) of 0.12mm. A stainless-steel ring having a width of 0.3 mm and an internal diameter of 2.5 mm was positioned on top of the ingress barrier and the ingress barrier membrane was affixed to the stainless steel ring with an adhesive to produce an ingress barrier assembly according to the invention.

[0083] To measure the acoustical properties, the ingress barrier assembly was affixed to a dome, as shown in Figure 6.

[0084] Prophetic Example 2 describes an experiment in which an ingress barrier assembly according to the present invention is prepared by molding a polysiloxane membrane onto a titanium ring having a width of 0.31 mm and an internal diameter of 2.5 mm, curing the polysiloxane membrane until curing is partly complete, sufficiently complete to allow handling of the membrane / titanium ring assembly, and affixing the membrane / titanium ring assembly onto a dome as shown in Figure 6, stretching the membrane moulded onto the titanium ring by applying a force 5, 35 perpendicular to the membrane plane by blowing compressed air against membrane 1 as described above in relation to Figure 1(a) and as depicted substantially as in Figure 5(b), continuing curing in an oven at 130°C whilst continuing to apply the force for 4 hours, until curing is substantially complete and allowing the membrane to relax. The cured polysiloxane ingress barrier assembly has a diameter of 2.5 mm, an average thickness of 10 pm, a Young's modulus of 2MPa, a Shore A hardness of 40, and a slackequivalent of 0.3 mm.

[0085] Example 3 describes an experiment in which a membrane for use in an ingress barrier assembly according to the present invention was prepared by compression molding a polysiloxane being a commercially available room temperature vulcanization polysiloxane variant using a platinum based curing agent into a flat membrane having an average thickness of 10 pm and curing at 80°C for 30 minutes. The cured polysiloxane membrane had an average thickness of 10 pm, a Shore A hardness of 40 and a Young's modulus of 2.5MPa.

[0086] Example 4 describes an experiment in which an ingress barrier assembly according to the present invention was prepared similarly to the membrane of Example 3, but curing the polysiloxane membrane until curing is partly complete, sufficiently complete to allow handling of the membrane. A stainless steel ring having a width of 3mm and an internal diameter of 2.5 mm was positioned on top of a membrane manufactured in accordance with the experiment described in Example 3, which membrane was itself positioned on top of a flat surface with a blunt cylindrical protrusion with a diameter of 2 mm and a height of 1 mm relative to the flat surface, substantially as depicted in Figure 1. The membrane was affixed to the stainless-steel ring by cleaning the steel ring with a plasma pre-treatment; applying a silicone primer followed by applying a silicone glue to the steel ring; and gluing the membrane to the stainless steel ring. The ingress barrier assembly, comprising an ingress barrier having a diameter of 2.5 mm, an average thickness of 10 pm, a Young's modulus of 2MPa and a slackeqUiVaient of 0.31 mm and a frame in the form of a rigid stainless steel ring, was removed from the surface after a final cure at 130°C for 4 hours. The acoustical properties of the ingress barrier assembly were measured whilst affixed to a dome, as shown in Figure 6.

[0087] Example 5 describes another experiment in which an ingress barrier assembly according to the present invention was prepared. A polysiloxane rubber ring having a width of 3.14 mm and an internal diameter of 2.5 mm was molded as one piece together with a membrane, using the same polysiloxane as used for the manufacture of the membrane described in Example 3. The rubber ring and membrane assembly was positioned in a stainless steel ring having an internal diameter of 3.12 mm, thereby introducing slackeqUiVaient in the membrane, as depicted in Figures 2 and 4. The ingress barrier assembly thus produced, comprised an ingress barrier membrane having a diameter of 2.5 mm, an average thickness of 10 pm, a Young's modulus of 2.5MPa and a slackeqUiVaient of 0.195 mm contained in a frame in the form of a rubber ring / metal ring assembly. To measure the acoustical properties, the stainless- steel ring was affixed to a dome, as shown in Figure 4.

[0088] Comparative Example 6 describes an experiment in which an ingress barrier assembly not according to the present invention was prepared from the membrane of Example 3. A stainless-steel ring having a width of 3 mm and an internal diameter of 2.5 mm was positioned on top of a membrane manufactured in accordance with the experiment described in Example 3, which membrane was itself positioned on top of a flat surface. The membrane was affixed to the stainless-steel ring by spraying an adhesive onto the stainless-steel ring and applying the stainless-steel ring to the membrane. The ingress barrier assembly not according to the invention, comprising an ingress barrier having a diameter of 2.5 mm, an average thickness of 10 pm, a Young's modulus of 2.5 MPa and substantially no slackeqUiVaient, contained in a stainless-steel ring, was removed from the surface.

[0089] To measure the acoustical properties, the comparative ingress barrier assembly with substantially no slackeqUiVaient was affixed to a dome, as shown in Figure 6.

[0090] Example 7 describes an experiment in which acoustical properties of the ingress barrier assemblies of Examples 1, 4, 5 and Comparative Example 6, whilst contained in / affixed to a dome were measured. Domes containing the ingress barrier assemblies were mounted in a conical coupler interface piece connected to a G.R.A.S. RA0045 coupler with a reference microphone which is a combination of a G.R.A.S. 40AG cartridge and G.R.A.S. 26AK preamplifier. Sound was produced by a Sonion 2600 type receiver connected to an Audio Precision type APx525 audio analyzer via a buffer amplifier, the output of the reference microphone was measured using the same APx525 analyzer via a reference microphone voltage supply, see Figure 14, the Sound Pressure Level (SPL) and Total Harmonic Distortion (THD) at a frequency range from 100 - 10000 Hz was measured by applying a swept sine signal in the range of lOOmV to 3V to the receiver and compared with an experiment where no ingress barrier assembly was present.

[0091] The results are presented in Figures 8, 9, 10 and 11, wherein Figure 8 depicts SPL and THD measurements of 10 samples of ingress barrier assemblies of Example 5; Figure 9 depicts SPL and THD measurements of 4 samples of ingress barrier assemblies of Example 4; Figure 10 depicts SPL and THD measurements of 2 samples of ingress barrier assemblies of Example 1; and Figure 11 depicts SPL and THD measurements of 6 samples of ingress barrier assemblies of Comparative Example 6.

[0092] The results are summarized in Table 1 below.

[0093] Table 1

[0094] Comparative Example 8: SmartGuardtmwax protector is commercially available from Phonak. The SmartGuardtmwax protection system comprises a membrane on a carrier ring. The membrane was analysed to be a thermoplastic polyurethane membrane with an internal diameter, within the carrier ring, of 2.6 mm and a thickness of 14 pm. In a number of samples, some wrinkles were observed in the membrane, and the displacement was determined to be in the range from 0.08 to 0.12 mm according to the method set out in more detail below, with reference to Figures 12 and 13. SlackeqUivaient was determined according to the formula set out above to be in the range from 0.09 to less than 0.13 mm. A stable increase in displacement with increasing DC pressure could only be reached at 0.3 kPa and the tension point was determined to be 0.3 kPa. Four samples were analysed and compared against a carrier ring where the SmartGuardtmmembrane had been removed. The acoustical properties were determined in the same experimental set up as in Example 7. The output (SPL) across the frequency range of 100 to 10000 Hz was smooth, with no artefacts, but significant damping variation was observed. The second frequency response peak virtually disappeared in 2 of the 4 samples and in 2 other samples the second frequency response peak was shifted to a lower frequency with limited damping. The Total Harmonic Distortion was more than 3%, in the range of 4-8% for all samples measured, in particular around 3000 Hz.

[0095] Example 9: Example 5 was repeated to prepare an ingress barrier assembly according to the invention, but instead of using a membrane of example 3, a membrane was prepared in essentially the same way as in example 3, but using a liquid polysiloxane, commonly referred to as liquid silicone rubber (LSR) having a platinum based curing agent. The LSR was cured at 160°C for 10 minutes. The cured membrane had an average thickness of 10 pm and a Young's modulus of 2.5 MPa. The acoustic transparency of the ingress barrier assembly according to this example was comparable to the ingress barrier assemblies according to example 5. The output (SPL) was smooth, with essentially no artefacts and no damping observed. The Total Harmonic Distortion was less than 3%.

[0096] Figure 12 depicts an analytical set-up for determining slack. Figures 12(a) and (c) show in cross-section, ingress barrier assemblies comprising a rigid ring, such as a stainless-steel ring 70 having an internal diameter of 2.5 mm to which an ingress barrier membrane 71, 72 is attached. In Figure 12(a) ingress barrier membrane 71 contains slack, whereas in Figure 12(c) ingress barrier membrane 72 is substantially flat, without slack. Ingress barrier assemblies 70, 71 and 70, 72 are placed in a DC pressure set up 75 where a DC pressure is applied, sufficient to get the membrane in a curved, tensioned position. Figure 12(b) depicts the ingress barrier assembly of Figure 12(a) in a tensioned position and Figure 12(d) depicts the ingress barrier assembly of Figure 12(c) in a tensioned position. Typical DC pressures that are applied range from 0.0 to 0.7 kPa. For the Ingress barrier assembly according to the invention, DC Pressures up to 0.7 kPa are sufficient to bring the ingress barrier membrane in a tensioned position without substantially stretching the ingress barrier membrane, i.e. substantially without elastically deforming the ingress barrier membrane. By measuring the distance, the difference in height of the membrane at the centre and the height where the membrane is connected to the ring, the displacement of the membrane is measured. A membrane is said to have slack where the displacement is at least 0.1 mm, absent elastic deformation of the membrane. In Figure 12(b) the difference in height is indicated by 73 and in Figure 12(d) the difference in height is indicated by 74. The difference in height is suitably measured by means of an optical surface profilometer.

[0097] Figure 13 shows results of slack measurements using the analytical set-up of Figure 12.

[0098] An ingress barrier assembly according to Example 9 was placed in the DC pressure set-up. The DC pressure was increased from 0.0 to 0.7 kPa and the height in the centre of the ingress barrier membrane was determined at various DC pressures in that range, using the method discussed above. Solid line 84a connects the various measurement points. It can be seen that the displacement as measured rapidly increases with application of a DC pressure of less than 0.1 kPa. Starting from a DC pressure of 0.1 kPa, tension point 89a on the graph, the rate of increase in displacement becomes substantially constant with increase in DC pressure to 0.7 kPa, indicative of elastic deformation. A straight dashed line 81a can be drawn connecting the measurement points where the rate of increase in displacement is substantially constant. The slack is the displacement where line 81a intersects with the Y- axis, at point 83a in the graph, i.e. at 0.196 mm.

[0099] An ingress barrier assembly according to Comparative Example 8 was placed in the DC pressure set-up. The DC pressure was increased from 0.0 to 0.7 kPa and the height in the centre of the ingress barrier membrane was determined at various DC pressures in that range, using the method discussed above. Solid line 88 connects the various measurement points. It can be seen that the displacement as measured rapidly increases with application of a DC pressure of less than 0.3 kPa. Starting from a DC pressure of 0.3 kPa, tension point 85 on the graph, the rate of increase in displacement becomes substantially constant with increase in DC pressure to 0.7 kPa, indicative of elastic deformation. A straight dashed line 87 can be drawn connecting the measurement points where the rate of increase in displacement is substantially constant. The slack is the displacement where line 87 intersects with the Y-axis, at point 86 in the graph, i.e. at 0.118 mm, which means a slackeqUivaient of 0.128 mm. Other samples of the ingress barrier assembly according to Comparative Example 8 had a displacement of less than 0.118 mm. The tension point, point 85 on the graph, was invariably at 0.3 kPa, irrespective of the slack that was measured.

[0100] An ingress barrier assembly according to Example 5 was placed in the DC pressure set-up. The DC pressure was increased from 0.0 to 0.7 kPa and the height in the centre of the ingress barrier membrane was determined at various DC pressures in that range, using the method discussed above. Solid line 84 connects the various measurement points. It can be seen that the displacement as measured rapidly increases with application of a DC pressure of less than 0.1 kPa. Starting from a DC pressure of 0.1 kPa, tension point 89 on the graph, the rate of increase in displacement becomes substantially constant with increase in DC pressure to 0.7 kPa, indicative of elastic deformation. A straight dashed line 81 can be drawn connecting the measurement points where the rate of increase in displacement is substantially constant. The slack is the displacement where line 81 intersects with the Y-axis, at point 83 in the graph, i.e. at 0.130 mm.

[0101] Figure 14 depicts an acoustical measurement setup for SPL and THD measurements. A dome, with or without ingress barrier assembly 95, connected to a receiver in canal 94 is connected to a coupler (711 / 2cc / l / 4cc) 97, via a conical coupler interface 96. Signal generator 92 is connected via buffer amplifier 99 to the receiver in canal 94 and causes the receiver to generate sound output. Sound travels through dome with or without ingress barrier assembly 95; conical coupler interface 96 and coupler 97 to a measurement microphone 98, and the signal output of measurement microphone 98 is connected to measurement input 93 in audio analyser 91 via reference microphone supply 90.

[0102] Whilst Figures 4-7 show ingress barrier assemblies where a frame is provided in the form of a rigid ring and / or as integral part of a dome, the present invention is not limited thereto. Figure 15 illustrates various designs of the frame part of the ingress barrier assembly in cross-section. Ingress barrier membrane 100 is connected to frame 101, 102, 103. Sound channel 105 is provided in the frame 101, 102, 103 for the passage of sound. The frame 101, 102, 103 may be provided with an engagement structure for releasably attaching the ingress barrier assembly to another part of a hearing device (not shown) such as a receiver housing or nozzle, a wax bucket, a custom-made shell, a microphone housing or nozzle or other part of a hearing device or hearable that is at risk of contamination with cerumen, wax ingress. Alternatively, the ingress barrier assembly may be used to protect openings in a hearable or hearing device against water. In Figure 15(a) the engagement structure is in the form of a protrusion 106; in Figure 15(c) the engagement structure is in the form of an indentation 107; and in Figure 15(b) the engagement structure is in the form of a stud 108. It will be appreciated that other engagement structures may be possible.

[0103] It will be appreciated that the ingress barrier assembly and / or the dome and / or the device according to the invention may be provided with a barometric vent to equalize pressure differences between the inner and outer part of an ear canal. Such barometric vent comprises a hole or tubular vent, typically having a diameter in the range of from 5 to 100 pm, preferably 30 to 60 pm. The barometric vent may according to one embodiment, be provided in the ingress barrier membrane. Other positions for the barometric vent include in the frame of the ingress barrier assembly; in the nozzle of a receiver in canal assembly; in a receiver, especially a back-vented receiver; and / or in a dome or other device as described herein.

[0104] In one embodiment, the barometric vent is provided in the receiver-in-canal housing (RIC housing) or in an protective element of the RIC housing, such as a sleeve enclosing the RIC housing, so as to provide a "vented RIC housing". In such embodiments, the vented RIC housing, in combination with the ingress barrier assembly and / or dome and / or device according to the invention, seals the receiver from any ingress of water, humidity, or debris, advantageously enabling a water-proof RIC. The barometric vent is advantageous to provide a THD-free hermetic barrier to the system (receiver / receiver housing). In some embodiments of the vented RIC housing, the barometric vent is provided as an air path to the receiver back volume. The barometric vent may be provided as a porous element that allows air to pass through at a small rate, such as but not limited to a porous filter, e.g. Gore-Tex™ membrane, zeolite membrane and the like. Alternatively, the barometric vent may be provided as a very small hole, or a tube vent (optionally with an internal wire to reduce inner diameter and keep the hole at the desired smallness) to the receiver back volume. It will be appreciated that, in some embodiments, the ingress barrier assembly and / or the dome and / or the device according to the invention may be provided with a surface treatment to prevent foreign material such as dust, hair, fibers, wax, etc., stick to the ingress barrier assembly and / or the dome and / or device outer material. Advantageously, the surface treatment reduces the coefficient of friction and helps introducing the ingress barrier assembly and / or the dome and / or device in the ear canal. Examples of surface treatment substances include but are not limited to silicones comprising decamethylcyclopentasiloxane, dodecamethylcyclohexanesiloxane, etc. Commercially available medical grade silicone coatings are represented e.g. by Siliskin (COP-Chimie) Although the present invention has been discussed in the foregoing with reference to exemplary embodiments of the invention, the invention is not restricted to these particular embodiments which can be varied in many ways without departing from the invention. The discussed exemplary embodiments shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary, the embodiments are merely intended to explain the wording of the appended claims, without intent to limit the claims to these exemplary embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using these exemplary embodiments.

Claims

23CLAIMS1. Ingress barrier assembly comprising a frame defining a sound opening for the passage of sound and an ingress barrier membrane covering the sound opening, wherein the ingress barrier membrane has a Young's modulus of less than 0.1 GPa, and is configured such that the ingress barrier membrane has a slackeqUivaient of more than 0.1 mm and a tension point of less than 0.2 kPa.

2. Ingress barrier assembly as claimed in claim 1, wherein the ingress barrier membrane has a Young's modulus of less than 0.05 GPa.

3. Ingress barrier assembly as claimed in claim 1 or claim 2, wherein the ingress barrier membrane has a Young's modulus of more than 0.0005 GPa.

4. Ingress barrier assembly as claimed in any one of the preceding claims, wherein the ingress barrier assembly is configured such that the ingress barrier membrane has a slackeqUivaient of more than 0.15 mm.

5. Ingress barrier assembly as claimed in any one of the preceding claims, wherein the ingress barrier assembly is configured such that the ingress barrier membrane has a slackequivalent of less than 0.3 mm.

6. Ingress barrier assembly as claimed in any one of the preceding claims wherein the ingress barrier membrane is configured so that the tension point is less than 0.15 kPa.

7. Ingress barrier assembly as claimed in any one of the preceding claims wherein the ingress barrier membrane is configured so that the tension point is more than 0.001 kPa.

8. Ingress barrier assembly as claimed in any one of the preceding claims, wherein the ingress barrier membrane comprises a polymer material selected from the group of butyl rubber, polyisoprene rubber, ethylene vinyl acetate, natural rubber, polychloroprene, polyurethane elastomer, polysiloxane, styrene (optionally hydrogenated) alkylene block copolymer and other thermoplastic elastomers.

9. Ingress barrier assembly as claimed in claim 8, wherein the ingress barrier membrane comprises a polysiloxane having a shore A hardness in the range of from 1 to 50, preferably 3 to 45.

10. Ingress barrier assembly according to any one of the preceding claims, wherein the frame is a rigid frame, the rigid frame preferably having a Young's modulus of at least 0.1 GPa.

11. Ingress barrier assembly according to claim 10, wherein the rigid frame is a rigid ring.

12. Ingress barrier assembly according to claim 11, wherein the ingress barrier membrane is positioned on or in a rubber ring, wherein the rubber ring is enclosed by the rigid ring, the rubber ring having an outer diameter of at least 0.001 mm more than the internal diameter of the rigid ring.

13. Use of an ingress barrier membrane mounted on or in a rubber ring, wherein the ingress barrier membrane has a Young's modulus of less than 0.1 GPa and substantially no slackeqUivaient, wherein the use of said membrane is in an ingress barrier assembly according to claim 12.

14. Method for making an ingress barrier assembly of claim 1 comprising the steps of (1) moulding a membrane from a thermoset elastomer such as a polysiloxane: (2) curing the membrane until the membrane is substantially demouldable and (3) affixing the membrane to an ingress barrier frame; or (1) moulding a membrane and ingress barrier frame together from a thermoset elastomer such as a polysiloxane: (2) curing the membrane and ingress barrier frame assembly until the membrane and ingress barrier frame assembly is substantially demouldable; followed by applying excess pressure to one side of the membrane, and continuing curing whilst continuing to apply pressure until curing is essentially complete, releasing pressure and yielding the ingress barrier assembly.

15. Dome comprising a dome sound opening for the passage of sound and an ingress barrier assembly in accordance with any one of claims 1-12, wherein the frame is at least that part of the dome surrounding the dome sound opening and wherein the ingress barrier membrane covers the dome sound opening.

16. Dome according to claim 15, wherein the ingress barrier membrane comprises a curable polymer membrane, obtainable by molding a dome with a curable polymer membrane, partly curing the polymer membrane, applying pressure to the polymer membrane and continuing curing the polymer membrane, followed by releasing the pressure.

17. Dome according to claim 15 or 16, comprising a flexible circumferential member arranged circumferentially around the dome sound opening, wherein the flexible circumferential member is configured to mechanically disconnect from at least the part of the dome sound opening comprising the ingress barrier membrane.

18. Device or device part comprising a device sound opening for the passage of sound and an ingress barrier assembly according to any one of claims 1-12 wherein at least the ingress barrier membrane is configured to cover the device sound opening.

19. Device or device part according to claim 18, wherein the device or device part is selected from the group of transducers, wax filters, transducers in canal assemblies, earbuds, hearables, and hearing devices.

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