Patent Publication Number: US-2022217484-A1

Title: Ingress protection from foreign material in hearing instruments

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/907,276 filed Sep. 27, 2019 and U.S. Provisional Application No. 62/941,250 filed Nov. 27, 2019, the contents of each of which are incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to hearing assistance devices such as hearing aids, wireless ear-buds, head-sets, and other devices for hearing sound. 
     BACKGROUND 
     Hearing assistance devices (also commonly referred to as “hearing aids” and “hearing instruments”) include tubes or other apertures through which foreign material enters hearing assistance devices. The foreign material, such as water, sweat, wax, and the like, can negatively impact the operation of the hearing assistance devices. 
     SUMMARY 
     In one example, the disclosure describes a hearing assistance device comprising an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user when the hearing assistance device is worn, and a tube coupled to the receiver to direct the sound waves into the ear canal of the user, wherein the tube comprises magnetized particles that form a magnetic field through the tube. 
     In one example, the disclosure describes a hearing assistance device comprising an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user when the hearing assistance device is worn, and a tube coupled to the receiver to direct the sound waves into the ear canal of the user, wherein the tube comprises a portion of hydrophilic coating and a portion of hydrophobic coating. 
     In one example, the disclosure describes a hearing assistance device comprising an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user when the hearing assistance device is worn, a tube coupled to the receiver to direct the sound waves into the ear canal of the user, and a coiled wire configured to carry an alternating current to generate an electro-magnetic field through the tube. 
     The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description, drawings, and claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A through 1D  are conceptual diagrams illustrating an example hearing assistance system, in accordance with one or more aspects of the present disclosure. 
         FIG. 2  is a conceptual diagram illustrating an example of a surface of a tube of a hearing assistance device having at least one of hydrophobic and hydrophilic layers. 
         FIGS. 3A-3D  are conceptual diagrams illustrating different perspectives of a tube of a hearing assistance device having magnetized particles. 
         FIG. 4  is a block diagram illustrating an example of a tube of a hearing assistance device immersed in a magnetic field. 
         FIG. 5  is a block diagram illustrating another example of a tube of a hearing assistance device immersed in a magnetic field. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to example techniques to protect hearing assistance devices from ingress of foreign material. For example, sweat from the user may enter through an aperture in the hearing assistance device. As another example, water from showering or swimming may enter through an aperture in the hearing assistance device. As yet another example, earwax build-up may enter through an aperture in the hearing assistance device. 
     A user may periodically clean the hearing assistance device. However, if the user fails with upkeep of the hearing assistance device, the foreign material may impede the operation of the hearing assistance device. For example, in a behind-the-ear (BTE) hearing aid, a behind-the-ear portion and an in-the-ear portion are coupled to one another via an acoustical conduit in the form of a tube, which may be hollow. Foreign material that enters through the tube may reach a transducer of the in-the-ear portion and cause the transducer to malfunction. 
     The disclosure describes example ways in which to limit the ingress of such foreign materials into the hearing assistance device, and in some examples, ways in which to push out the foreign material. A commonality between example foreign materials may be the existence of water. The example techniques described in this disclosure leverage the chemical properties of water as a way to change properties of the foreign material and slow down the ingress of the foreign material, including examples of expelling the foreign material from the hearing assistance device. For example, some existing techniques to slow down the ingress of foreign material or expel the foreign material from the hearing assistance device are not based on the chemical properties of water, such as in cerumen or sweat, that can be leveraged to slow down the ingress of or expel the foreign material, like cerumen or sweat. 
     As one example, a water molecule is a dipole molecule where the two oxygen-hydrogen bonds are oriented at an angle of approximately 104.5° with a dipole moment of 1.84 debyes (D). The dipolar nature of water allows its bulk properties to be influenced by electric and magnetic fields. Furthermore, sodium chloride and potassium chloride, two compounds contained in human cerumen within the ear canal, have dipole moments of 9.0 D and 10.2 D, respectively, which can also be influenced by electric and magnetic fields. There may be additional examples of foreign material. 
     As one example, water tends to flow through a path with lower magnetic field levels due to the diamagnetic property of water. Accordingly, in the presence of a magnetic field, the flow of water can slow down. In some examples, a tube of the hearing assistance device is formed with magnetic microspheres interspersed in the tube material. The magnetic microspheres have properties where, if an external magnetic field is applied to the oxide material, the magnetic microspheres are magnetized, and then once the external magnetic field is removed, the magnetic microspheres remain magnetized. Examples of magnetic microspheres include colloidal magnetic silica microspheres. In some examples, the tube may be formed with permanent magnets interspersed in the tube material. In some examples, recently formed magnetic liquid may be interspersed in the tube material. Other ways in which to include magnetized material in the tube are possible, and the techniques are not limited to the above examples. For instance, in some examples, the magnetized material may be within a coating that is cured on the tube, in addition to or instead of the magnetized material being formed in the tube material. Because the foreign material tends to include water, having a magnetic field emanating from the magnetic materials in the tube may reduce the rate of ingress of the foreign material. 
     Although water may flow through paths having lower magnetic field, water may still enter the magnetic field. Also, in some examples, there may not be magnetized material in the tube. In some examples, including examples where there is magnetized material in the tube and excluding examples where there is magnetized material in the tube, an electro-magnetic field source may be used to apply an electro-magnetic field to the foreign material. 
     When water is exposed to electro-magnetic fields, the dipole nature of the water causes the water molecules to align in a certain configuration. When aligned in the certain configuration, in response to being exposed to the electro-magnetic fields, the cohesive forces of the water molecules, and therefore, the cohesive forces of the foreign material are altered with the goal of containing the material to local regions, thereby inhibiting its ability to ingress onto critical electromechanical components such as acoustic transducers. 
     A hearing assistance device, in accordance with one or more examples described in this disclosure, may be configured with an electro-magnetic field source. The electro-magnetic field source outputs an electro-magnetic field that causes the water molecules of the foreign material to orient in a manner that lowers the cohesive force of the foreign material. 
     In some examples, an internal energy source may output energy that pushes out the foreign material out of the hearing assistance device, or at least impedes the movement of the foreign material towards the hearing assistance device. As one example, a hearing assistance device includes an acoustic source (e.g., internal energy source) that is configured to generate an acoustic wave having a frequency outside of human hearing range that gently and slowly pushes the foreign material outwards. As another example, a vibrating source is an example of the internal energy source, and the vibrating source causes the tube to vibrate and gently dislodge the foreign material. 
     Due to power constraints and that the hearing assistance device is in the ear, in one or more examples, the techniques may be related to low energy usage such that the foreign material is gently moved or dislodged. Furthermore, low energy techniques may ensure no negative impact to the user such as impact on hearing. 
     Moreover, the example hearing assistance devices may be configured with additional materials to protect against the ingress of foreign materials. As one example, portions of a hearing assistance device may be engineered with a certain texture or coated in a hydrophobic material to repel water molecules, and portions of the hearing assistance device may be engineered with a different texture or coated in a hydrophilic material that tends to bond with water molecules. In some examples, texturing may be sufficient to form hydrophobic and/or hydrophilic portions without the need for additional coatings or materials (e.g., textures can achieve similar results as coatings). In this manner, the foreign material is guided away from the hydrophobic material and towards the hydrophilic material. Based on the location of the hydrophilic and hydrophobic materials, it may be possible to slow the ingress of the foreign material in the hearing assistance device. 
     The above example techniques may be performed together or separately. For example, a hearing assistance device may include one or more (e.g., subset) of magnetic material, an electro-magnetic field source, an internal energy source, and hydrophobic and/or hydrophilic material but not all of magnetic material, an electro-magnetic field source, an internal energy source, and hydrophobic and/or hydrophilic material. In some examples, the hearing assistance device may include all of magnetic material, an electro-magnetic field source, an internal energy source, and hydrophobic and hydrophilic material. In some examples, the magnetic material may be part of the hydrophobic or hydrophilic material. 
     Moreover, the above examples are described with respect to the tube of the hearing assistance device, but the example techniques are not so limited. The example techniques may be applied to other parts of the hearing assistance device. For example, the hydrophobic and/or hydrophilic material may be used in the tube and/or in the body of the hearing assistance device. 
     Although described primarily from the perspective of hearing assistance devices or hearing assistance systems, the described techniques are applicable to other types of “hearables.” For example, the described techniques are applicable to a hearing assistance device, a hearing instrument, a hearing aid, a personal sound amplification product (PSAP), a headphone set, an earbud, a wireless ear-bud, or other hearing instrument that provides sound to a user for hearing. 
       FIGS. 1A through 1D  are conceptual diagrams illustrating an example hearing assistance system, in accordance with one or more aspects of the present disclosure.  FIG. 1A  shows an example of system  100 A which includes portable case  104  and hearing assistance device  102  (referred to simply as “HAD  102 ”).  FIG. 1B  shows an example of system  100 B, as an alternate view of system  100 A, after tube  110  has been detached from behind-ear portion  106 A.  FIG. 1C  shows HAD  102 A as an example of HAD  100  from  FIGS. 1A and 1B . HAD  102 A includes behind-ear portion  106 A, tube  110 , and in-ear portion  108 .  FIG. 1D  shows HAD  102 B as an example of HAD  100  from  FIGS. 1A and 1B . HAD  102 B omits behind-ear portion  106 A and includes only tube  110  and in-ear portion  108 . 
     In the example of  FIG. 1A , HAD  102  includes behind-ear portion  106 A coupled to in-ear portion  108  via tube  110 . Behind-ear portion  106 A of HAD  102  is housed in a retention structure of portable case  104 , for example, either to be subsequently detached from tube  110  for charging, or to be removed from portable case  104  via tube  110  to be worn by a user. In addition to storing (and in some instances charging) behind-ear portion  106 A, portable case  104  also may charge one or more other behind ear portions. For example, in  FIG. 1A , portable case  104  is also shown storing and/or charging behind ear portions  106 B and  106 N. 
     In  FIG. 1B , tube  110  and in-ear portion  108  have been detached from behind-ear portion  106 A. With tube  110  and in-ear portion  108  removed,  FIG. 1B  shows openings  116  in cover  118  of portable case  104 , which are included in cover  118  to enable insertion and removal of behind-ear portions  106 A, B, and N. Also identified in  FIG. 1B  are retention structures  112 A and  112 N; each of retention structures  112 A and  112 N is configured to retain one of behind-ear portions  106 . As one example, retention structure  112 N is empty and retention structure  112 A includes behind-ear portion  106 A. 
     In the examples of each of  FIGS. 1A and 1B , portable case  104  is configured in a carousel arrangement to facilitate quick and easy exchange of one behind-ear portion  106  for a different behind-ear portion  106 . In other examples, portable case  104  may be configured in a linear or other such arrangement. 
     A user may manipulate cover  118  of portable case  104  to expose, via openings  116 , an individual retention structure  112  or multiple retention structures  112  at a time (e.g., to retrieve a pair of behind-ear portions  106 ). For example, a user may manipulate cover  118  to expose, via one of openings  116 , retention structure  112 A (which is empty at the time). Next, the user may insert behind-ear portion  106 A into retention structure  112 A and detach behind-ear portion  106 A from tube  110 . The user may then manipulate cover  118  to cover retention structure  112 A and expose, via one of openings  116 , retention structure  112 N. Finally, the user may attach behind-ear portion  106 N to tube  110  and remove behind-ear portion  106 N from retention structure  112 N. 
     Although primarily described as being a rotary type cover (e.g., similar to that which may be used for some types of fishing tackle containers such as rotary slip shot sinker containers), cover  118  may be a hinge type cover (e.g., similar to a typical dental floss container lid) configured to flip up and down to open and close. Alternatively, cover  118  may be configured to slide to open and close. Cover  118  may be configured to reveal two or more retention structures  112  at a time (e.g., via openings  116 ) so multiple behind-ear portions  106  could be changed without further manipulation of cover  118 . Likewise, cover  118  may be configured to reveal a single one of retention structures  112  at a time or more than two retention structures  112  at a time. 
       FIG. 1C  shows an example of HAD  102 A which includes behind-ear portion  106 A, tube  110 , and in-ear portion  108 .  FIG. 1D  shows an example of HAD  102 B omitting behind-ear portion  106 A and including only tube  110  and in-ear portion  108 . 
     Various attachment features can be used to attach behind-ear portion  106 A to portable case  104  and to attach behind-ear portion  106 A to tube  110 . The various attachment features may include mechanical and/or magnetic components that enable easy (e.g., one-handed) exchange of behind-ear portion  106 A to and from portable case  104  and to and from tube  110 . 
     For example, as shown in  FIGS. 1C and 1D , tube  110  includes attachment feature  150  (also referred to as “coupling feature  150 ”). Attachment feature  150  is configured to mate with an attachment feature of behind-ear portion  106 A. When detached from attachment feature  150 , the attachment feature of behind-ear portion  106 A is configured to mate with one of retention structures  112 . Such attachment features may include mechanical and/or magnetic components that enable tube  110  and behind-ear portion  106 A to maintain a strong physical bond when being worn, enable retention structures  112  and behind-ear portion  106 A to maintain a strong physical bond when behind-ear portion  106 A is charging. Such mechanical and/or magnetic attachment features may further enable behind-ear portion  106 A to quickly disconnect from retention structures  112  and tube  110 . 
     In some examples, a mechanical catch may prevent two parts from being detached without sufficient force for overcoming the mechanical catch. And, in the case of a magnetic feature, the attachment features may be a mechanically and/or magnetically self-aligning design. That is, to configure behind-ear portion  106 A for use, a user may simply bring attachment feature  150  near an attachment area of behind-ear portion  106 A and the magnetic attraction between attachment feature  150  and the attachment area of behind-ear portion  106 A may force the two parts together and enable an electrical connection between the two parts. Similarly, to configure behind-ear portion  106 A for storage or charging in portable case  104 , a user may simply position the attachment area of behind-ear portion  106 A above an empty one of retention structures  112 , and the magnetic attraction between the empty retention structure  112  and the attachment area of behind-ear portion  106 A may allow a user to simply drop behind-ear portion  106 A into the empty retention structure  112  where the electrical contacts of behind-ear portion  106 A may automatically align with the charging contacts of the empty one of retention structures  112 . 
     In some cases, the mechanical and/or magnetic attachment features described above enable release of their bonds via rotation. That is, with both portable case  104 , behind-ear portions  106 , and attachment feature  150  of tube  110  having magnets or mechanical catches, the magnets and/or mechanical catches can be configured so that after two parts are physically mated together, a ninety-degree rotation of either part may cause the magnetic attraction to switch to magnetic repulsion or may cause the mechanical catch to be bypassed, thereby releasing one part from the other. For example, to remove behind-ear portion  106 A from portable case  104 , a user can simply turn either part, e.g., ninety degrees, to cause behind-ear portion  106 A to pop out of case  104 ; to detach behind-ear portion  106 A from tube  110 , a user can simply turn either part, e.g., ninety degrees, to cause behind-ear portion  106 A to separate from tube  110 . 
     The attachment features described above may be improved via an electro-permanent magnetic catch. For example, portable case  104  may include circuitry to cause electro-permanent magnets in retention structure  112 A to have a greater amount of magnetic attraction to behind-ear portion  106 A when charging to prevent a user from separating the two parts prematurely. When behind-ear portion  106 A is charged, portable case  104  may activate circuitry to switch the electro-permanent magnet of retention structure  112 A to reduce the magnetic attraction between the two parts and enable mechanical disengagement of the charged behind-ear portion  106 A with minimal force. Similar electro-permanent magnets may be used in tube  110  for varying the magnetic attraction between attachment feature  150  and behind-ear portion  106 A depending on whether the parts are being mated together or separated. 
     Tube  110  provides a mechanism to connect in-ear portion  108  and behind-ear portion  106 A. For example, behind-ear portion  106 A includes a microphone, amplifier, and receiver (also called speaker). The microphone captures sound and converts the sound into electrical signals. The amplifier amplifies the electrical signals, and possibly performs some filtering operations. The speaker receives the amplified electrical signals and generates sound waves through tube  110  into in-ear portion  108 . 
     Tube  110  may also provide an inlet for foreign material that can enter and travel to behind-ear portion  106 A and cover the receiver (also called speaker) within behind-ear portion  106 A. The foreign material may also clog tube  110  reducing the amount of sound waves that enter the ear canal. Examples of the foreign material include sweat and cerumen (earwax). For example, sweat and/or cerumen may gather within the ear and travel through tube  110  to the receiver within behind-ear portion  106 A. The foreign material may cover the receiver and negatively impact sound traveling to the ear canal through in-ear portion  108 . 
     The above description is described with respect to a receiver in canal (RIC) or behind-the-ear (BTE) configuration. However, the example techniques described in this disclosure are applicable to other examples of hearing assistance devices. For example, the example techniques are applicable to invisible in canal (IIC), completely in canal (CIC), mini in canal (MIC), microphone in helix (MIH), and in the ear (ITE) hearing aids as a few examples. 
     In general, the example techniques are applicable to examples where a hearing assistance device includes an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user. The receiver may be in the behind-ear portion  106 A, or in the enclosing structure of the IIC, CIC, MIC, MIH, or ITE. For IIC, CIC, MIC, MIH, or ITE, there may not be a tube as large as tube  110 . However, for IIC, CIC, MIH, or ITE, there is some structure through which sound waves travel into the ear canal of the user. The example techniques described in this disclosure for tube  110  are applicable to the structures through which sound travels in hearing assistance devices other than a BTE. That is, tube  110  and the structure through which sound waves travel into the ear canal of a user in IIC, CIC, MIC, MIH, or ITE are all examples of a tube coupled to the receiver to direct sound waves into the ear canal of the user. For ease of description, the examples are described with respect to tube  110 , but the techniques are applicable to other types of tubes for other hearing assistance devices (e.g., techniques are applicable to structures in hearing assistance devices through which sound waves travel into the ear canal of the user). 
     As described above, foreign material such as sweat or cerumen can clog tube  110  or deposit on the receiver, thereby impacting the operation of the hearing assistance device. For example, water, sodium, and potassium in tube  110  can impact the operation of the hearing assistance device. The above examples of foreign material entering or forming in tube  110  are non-limiting and the example techniques described in this disclosure are applicable to other example ways in which foreign material may ingress into tube  110 . 
     One commonality of the example foreign material is the inclusion of water. The example techniques described in this disclosure may exploit the chemical properties of water to condition the foreign material or the tube such that ingress of the foreign material through the tube is slowed and potentially to condition the foreign material or the tube such that the foreign material can be more easily expelled from the tube. For example, the techniques described in this disclosure may utilize magnetic fields and/or hydrophobic and hydrophilic materials (e.g., coatings) to slow down or expel foreign material from the tube. In examples where magnetic fields are utilized, this disclosure describes example techniques that utilize sufficiently low-level magnetic fields to slow down or expel foreign material while ensuring no impact to the hearing of the patient. Existing techniques may not have been based on the properties of the foreign material, like cerumen or sweat, that allow magnetic fields to slow down or expel such foreign material from the tube. 
     For example, water is a diamagnetic material, and tends to flow through paths where magnetic field levels are minimized. In some examples, tube  110  may be formed with magnetized materials that generate a magnetic field through tube  110 . The magnetic field through tube  110  may then slow the ingress of the foreign material in tube  110  and reduce the chances of the foreign material clogging tube  110  or the foreign material reaching behind-ear portion  106 A. 
     As another example, tube  110  may be formed with at least one of hydrophilic coating and at least one hydrophobic coating. The hydrophilic coating attracts (e.g., pulls) water and hydrophobic coating repels water. By using a combination of a hydrophilic coating and a hydrophobic coating, it may be possible to move the foreign material in a particular location or direction so that the foreign material can be easily removed such as when tube  110  is removed for manual cleaning. 
     In some examples, the hydrophobic and/or hydrophilic coatings may be applied to behind-ear portion  106 A or in-ear portion  108  to direct the foreign material in a particular direction or to restrict foreign material from entering behind-ear portion  106 A and/or in-ear portion  108 . For example, behind-ear portion  106 A may be formed with a plurality of segments that are sealed. Even though the plurality of segments are sealed, there is a possibility of water entering through the seam created from connecting the segments. By applying a hydrophobic coating at the seam between the segments, there is a reduction in the chances of water entering through the seam. 
     Using magnetized materials in tube  110  and using a hydrophobic and/or hydrophilic coating are two example ways in which ingress of foreign material can be slowed (e.g., with magnetized materials in tube  110 ) or controlled (e.g., with hydrophobic and/or hydrophilic coating). In some examples, behind-ear portion  106 A and/or in-ear portion  108  (e.g., such as in examples where the hearing assistance device is an IIC, CIC, MIC, or ITC) includes a drive circuit and a coiled wire. The drive circuit outputs an alternating current through the coiled wire that causes the coiled wire to radiate an electro-magnetic field. 
     The drive circuit and the coiled wire may be within behind-ear portion  106 A and near the receiver. The coiled wire may be external to tube  110 . In some examples, the drive circuit may be within behind-ear portion  106 A and the coiled wire may be coiled around tube  110  (e.g., encircling tube  110 ). 
     As described above, the water molecule is a dipole, and therefore, in the presence of a magnetic field, the water molecules reorient in a manner that changes the cohesive properties of the water molecules. With the current flowing through the coil, the resulting magnetic field may cause the foreign material to orient such that the foreign material is less likely to stick to the inside of tube  110 . 
     The user may periodically and manually clean tube  110 . By reducing the cohesiveness of the foreign material (e.g., through the application of an electro-magnetic field), by directing foreign material in a particular direction or location (e.g., through hydrophobic and/or hydrophilic coatings), and/or by reducing the amount of foreign material that ingresses into tube  110  (e.g., by including magnetized material in tube  110 ), the user may be able to more easily clean tube  110 . For example, the foreign material may be positioned such that there is a reduction in the amount of effort that the user needs to expend to clean tube  110 . 
     There may be other ways in which to clean tube  110 . As one example, behind-ear portion  106 A and/or in-ear portion  108  (e.g., such as in examples where the hearing assistance device is an IIC, CIC, MIC, or ITC) includes an energy source that can be used to expel the foreign material from tube  110 . One example of the energy source is a mechanical vibrating component that vibrates tube  110  can dislodges the foreign material. Another example of the energy source may be the receiver itself that is designed to generate an inaudible signal that pushes the foreign material through tube  110 . In some examples, such as by the inaudible signal vibrating tube  110  or by the inaudible signal pushing foreign material, the foreign material may travel towards the user&#39;s ear canal. However, the amount of foreign material may be sufficiently small that pushing the foreign material towards the user&#39;s ear canal does not cause any negative impact to the user (e.g., damage or discomfort). 
       FIG. 2  is a conceptual diagram illustrating an example of a surface of a tube of a hearing assistance device having at least one of hydrophobic and hydrophilic layers. For example,  FIG. 2  illustrates surface  200 . One example of surface  200  is tube  110  folded open to form a rectangular surface. Surface  200  may be an inner surface of tube  110  after tube  110  is folded open. 
     Surface  200  may be formed with at least one of hydrophobic and hydrophilic coatings. For example, surface  200  may include a portion of a hydrophilic coating and a portion of a hydrophobic coating. As one example, the hydrophilic coating can be a material such as Grilamid TR55-LX which has a surface energy contact angle of less than 90 degrees, anti-fog from Rain X, FluoroPel 800 from the company Cytonix for hydrophilic and hydrophobic coatings and bare Grilamid. Acetic acid (HAc) coating can be used for the hydrophobic coating as well. 
     Various design choices may be available when including hydrophobic or hydrophilic portions. The surface area of each coating may only be limited to the application method. The portions could be strips vertical, horizontal, flat, inside between or outside of the device from 0.025 inches to complete coverage of the surface. The geometry and orientation of the geometry should be taken in consideration and what is near that which is protected from the foreign material. A hydrophilic coating near electronics on a vertical surface would draw moisture from the air and condensate on the surface first and could be channeled by geometric texturing to another place with another kind of surface texture that has a hydrophobic coating to move the moisture from that area. The areas of each coating may be a factor in hydrophilic or hydrophobic coatings. 
     As one example, as illustrated in  FIG. 2 , surface  200  includes a plurality of strips  202 A- 202 D and a plurality of strips  204 A- 204 C. Strips  202 A- 202 D are one example of the portion of hydrophobic coating. Strips  204 A- 204 C are one example of the portion of hydrophilic coating. As illustrated, in some examples, strips  204 A- 204 C of hydrophilic coating are interleaved with strips  202 A- 202 D of hydrophobic coating. In some examples, strips  204 A- 204 C of hydrophilic coating interleaved with strips  202 A- 202 D of hydrophobic coating form a helix shape. 
     Also, although surface  200  is described as being part to tube  110 , the example techniques are not so limited. In some examples, surface  200  may represent the inner portion of the enclosing structure (e.g., behind-ear portion  106 A for BTE hearing assistance devices or in-ear portion  108  for IIC, MIC, ITE, CIC hearing assistance devices) that houses the receiver that transmits sound waves through tube  110 . In other words, the enclosing structure that includes the receiver may include a portion of hydrophilic coating and a portion of hydrophobic coating. 
     In some examples, surface  200  is a textured surface. For example, rather than being a smooth surface, surface  200  may include bumps and grooves. As a few examples, the textured surfaces may include V-Grooves, Simi-spheres, bumps and cones as a few typical geometry cuts and speed of the cutting tools leave tool marks. In some examples, water droplets may stick to the textured areas. When hydrophobic surface treatment is added to the textured area, the droplets may bounce off the textured area, which increases the sliding effect of the water droplets. When hydrophilic surface coating is applied to the textured area, the droplets may adhere to the surface with greater surface tension. This process amplified the coating that is applied to the textured surface. On example of the texture that is added to the chip is peaks of 0.0054″ spread apart at 0.0028″. 
     Accordingly, this disclosure describes examples of a hearing assistance device that includes an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user when the hearing assistance device is worn. Examples of the enclosing structure include behind-ear portion  106 A for BTE or in-ear portion  108  for IIC, CIC, MIC, MIH, or ITE. 
     The hearing assistance device also includes a tube (e.g., surface  200  when surface  200  is folded back to make tube  110 ) coupled to the receiver to direct the sound waves into the ear canal of the user. The tube (e.g., surface  200 ) comprises a portion of hydrophilic coating (e.g., strips  204 A- 204 C) and a portion of hydrophobic coating (e.g., strips  202 A- 202 D). 
       FIGS. 3A-3D  are conceptual diagrams illustrating different perspectives of a tube of a hearing assistance device having magnetized particles. For instance,  FIGS. 3A-3C  illustrate tube  300  and  FIG. 3D  illustrates tube  306 . Tubes  300  and  306  may be substantially similar, including identical, to tube  110  or the tube formed by folding back surface  200 . 
     As illustrated in  FIGS. 3A-3C , tube  300  include particles  302 A- 302 N. Particles  302 A- 302 N may be dispersed randomly throughout the volume formed between the external and internal surfaces of tube  300 . In some examples, particles  302 A- 302 N may be arranged in a particular pattern with a particular placement. The shape of particles  302 A- 320 N may be approximately spherical, and the size of particles  302 A- 302 N may be approximately 65 μm 3  (e.g., 5 μm diameter sphere). Particles  302 A- 302 N may occupy approximately 5% to 50% of volume between the external and internal surfaces of tube  300 . 
     Examples of particles  302 A- 302 N include permanent magnetic material (e.g., ferromagnetic and ferrimagnetic materials). In some examples, particles  302 A- 302 N may be magnetic microspheres, such as colloidal magnetic silica microspheres. In such examples, particles  302 A- 302 N may have the property that once magnetized, particles  302 A- 302 N remain magnetized. 
     The following are some examples of magnetic microspheres. For instance, various combinations of the elements iron (Fe), nickel (Ni), cobalt (Co) and gadolinium (Gd) are materials that may be used to form magnetic microspheres, including iron oxides. The combination of these metals has direct influence of the H field, which represents the magnetic field strength. These material combinations also influence the B field, which represents is the density of the magnetic field. These material combinations are considered ferromagnetic and will retain or not lose the field once the applied field is removed. As one example, a mix of chromium dioxide with the iron oxide may cause the combination to retain the magnetic field once the applied magnetic field is removed. The material could be used to manufacture parts that work with one or more, including all, examples described in this disclosure. The particle size of the material is 2 to 120 nanometers. The mix of chromium dioxide with the iron oxide may work in CFM-20-10 SPHERO™ Carboxyl Ferromagnetic Particles. 
     In general, most materials, including possibly any material, that remains ferromagnetic after being subjected to a magnetic field may be used as a magnetic microsphere. The types of materials that may not work as well are classified as paramagnetic (i.e., they react to a magnetic field but do not remain magnetic when that field is removed). 
     In some examples, a silica coating may be applied to the magnetic microspheres, which may offer processing ease, but such coating is not necessary. Chromium Dioxide may be added to the magnetic microspheres. In general, magnetic powder such as powders used to make neodymium magnets may be used in addition to or instead of magnetic microspheres. The smaller the powder (e.g., the more crushed) the less magnetism it has, and may be one way to impart a magnetic field with flux lines relatively perpendicular to the surface of debris ingress. In some examples, dependent on the degree of surface roughness, perpendicular may be a relative term to the degree of slope of the texture to the direction of ingress. If surface roughness depth is 0.0035″ and the peak to peak width is 0.004,″ the flux lines may be normal or orthogonal to the 59.490 degrees slope of the surface roughness. 
     Accordingly, in some examples, the magnetic microspheres are mixed within an injection-molded or injection-moldable material. When the injection-molded or moldable material is cured from a liquid state to solid within vicinity of a magnet to form an injection-molded part, the microspheres are aligned per the magnetic field from the magnet. 
     There may be other ways in which to include microspheres as particles  302 A- 302 N in tube  300 . For instance, in some cases, microspheres can be wasted in the vents of the molding tool when the magnetic microspheres are mixed with injection-molded material and injected into tube  300 . The microspheres may be expensive, and the wasted microspheres may result in unneeded extra costs. Also, in the examples where the microspheres are mixed with an injection-molded or moldable material and injected into tube  300 , it may be difficult to corral the microspheres to a particular region since the microspheres are pre-mixed and uniformly distributed throughout the injection resin (e.g., injection-molded material). 
     In some examples, rather than or in addition to using injection-molded or moldable material for including microspheres in tube  300  as particles  302 A- 302 N, a coating process may be utilized. For example, the injection-molded or moldable material is used to create a substrate and the substrate is cured (e.g., the substrate is injection molded and cured). 
     In the coating process, the cured part (e.g., substrate) is coated with a coating material includes one or more solvents and microspheres. In some examples, the coating may include hydrophobic, hydrophilic, and/or oleophobic (e.g., oil repellent) polymers and/or elastomers together with the one or more solvents and microspheres. After the coating is applied (e.g., brushed, dipped, sprayed, or any other application), the one or more solvents may flash off (e.g., flash cure) leaving the coating material and the microspheres (e.g., the hydrophobic, hydrophilic, and/or oleophobic polymers and/or elastomers and the microspheres may remain). Inclusion of the hydrophobic, hydrophilic, and/or oleophobic polymers and/or elastomers is not necessary in all examples. In this way, the one or more solvents may be removed as part of curing the coating. There may be various ways in which to “flash off” the one or more solvents such as by heat, evaporation, and the like. An example of magnetic materials being included in the coating material is illustrated in  FIG. 3D . 
     The coating material may cross-link with the substrate, and during this cross-linking stage, an external magnetic field may be applied to align the microspheres. That is, the one or more solvents allow the hydrophobic, hydrophilic, and/or oleophobic polymers and/or elastomers to cross-link with the substrate, and the microspheres are aligned during this cross-linking phase. The cross-linking phase may be a UV (ultra-violet) curing step but use external magnetic field. The result of applying the external magnetic field may be a thin material coating of cross-linked microspheres. Similar to above, these microspheres retain their magnetic properties and interact with the cerumen, keeping the cerumen from processing over a distance, etc. In some examples, the coating material, once the one or more solvents has flashed off, may be based on hydrophobic and/or hydrophilic compounds (e.g., including the hydrophobic, hydrophilic, and/or oleophobic polymers and/or elastomers). 
     A result of utilizing the coating process described above with a hydrophobic and/or hydrophilic compound may be that the coating is more likely to stay on tube  300  as compared to other techniques of including hydrophobic and/or hydrophilic coating. For instance, some other types of hydrophobic coatings may lack toughness and can easily scrape off of tube  300 . 
     In some examples, the injection-molded/moldable material may include polymers and/or elastomers in addition to the microspheres. The polymers and/or elastomers give the material hydrophilic, hydrophobic, and/or oleophobic properties such that when the solvent is flashed off, the remaining coating may be hydrophilic, hydrophobic, and/or oleophobic, and when a magnetic field is applied, the microspheres become magnetic and retain their magnetism to slow or stop the movement of cerumen, as described above. 
     In some examples, particles  302 A- 302 N may be droplets of magnetic fluid. Rather than having droplets of magnetic fluid, it may be possible for tube  300  to be filled with (partially or fully) magnetic fluid. Magnetic fluid may be similar to ferrofluid that becomes magnetic in the presence of a magnetic field. However, the magnetic fluid maintains its magnetism even after removal of the magnetic field. The magnetic fluid may include ferromagnetic nanoparticles suspended in fluid. The magnetic field may utilize iron oxide nanoparticles. In some examples, the magnetic fluid may be formed with injecting water into a tube of silicone oil mixed with a nanoparticle surfactant that forms an elastic film. The iron oxide nanoparticles may form a shell at the interface between the water droplets and the oil suspension. Examples of the magnetic fluid are described in https://www.sciencealert.com/scientists-have-printed-droplets-of-permanently-magnetic-liquid-and-boy-is-it-trippy. 
     As illustrated in  FIG. 3B , tube  300  temporarily includes magnets  304 A- 304 N during the molding process (e.g., a pin used during injection molding), where every other magnet is orthogonal to the previous and subsequent magnet. This orientation of magnets  304 A- 304 N magnetizes and/or aligns previously-magnetized particles  302 A- 302 N. For example, particles  302 A- 302 N align and then the injection molding material cures into an elastomer or plastic. Other orientations of magnets  304 A- 304 N are possible. Once magnetized, particles  302 A- 302 N form a magnetic field around tube  300 . In some examples, the magnetic field created by particles  302 A- 302 N at a location along the surface of the conduit is approximately within a range of 100 nanoTesla to 100 micro Tesla. 
     As illustrated in  FIG. 3C , tube  300  may temporarily include cylindrical magnets arranged with a common axis. As illustrated, the cylindrical magnets may alternate between N/S alignment.  FIG. 3C  illustrates the magnets with an oblique visual angle. 
     As described above, due to the diamagnetic properties of water, water tends not to flow through areas having a magnetic field. Therefore, the magnetic field formed by magnetized particles  302 A- 302 N slows ingress of a foreign material having water through tube  300  when the hearing assistance device is worn. 
       FIG. 3D  illustrates tube  306 , which includes conduit internal coating  310  with magnetic material, such as magnetized particles  302 A- 302 N. In  FIG. 3D , tube  306  is shown with bolded lines to distinguish the components illustrated in  FIG. 3D . For example, between the bolded lines of tube  306  is the volume formed between the external and internal surfaces of tube  306 . 
     Coating  310  is referred to as a conduit internal coating because coating  310  may be on an internal surface of tube  306 . For example, tube  306  forms conduit  308  that is surrounded by the internal surface of tube  306 . As described above, in some examples, coating  310  may be hydrophobic, hydrophilic, or oleophobic coating. The magnetic material, such as magnetized particles  302 A- 302 N, may be within the hydrophobic, hydrophilic, or oleophobic coating. That is, during the curing of coating  310  (e.g., due to heat or ultra-violet (UV)), the magnetic material remains cured on the internal surface of tube  306 . 
       FIG. 3D  also illustrates an example manner in which to magnetize the magnetic material in coating  310 . As one example, radially magnetized ring magnet  312  may be placed inside conduit  308 , with the south pole of ring magnet  312  proximate to the inner surface of tube  306  and the north pole of ring magnet distal from the inter surface of tube  306 . Radially magnetized ring magnet  314  may be placed outside tube  306 , which the north pole of ring magnet  314  proximate to the outer surface of tube  306  and the south pole of ring magnet  314  distal from the outer surface of tube  306 . 
     The pole-orientation of ring magnets  312  and  314  is illustrated as one example and should not be considered limiting. Also, the use of ring magnets  312  and  314  to magnetize particles may also be utilized in examples where magnetic particles  302 A- 302 N are within the volume formed between the external and internal surfaces of a tube, as illustrated in  FIG. 3A . In some examples, it may be possible to magnetize the magnetic material in coating  310 , in  FIG. 3D , using the example techniques described above with respect to  FIGS. 3B and 3C . Moreover, in the example illustrated in  FIG. 3D , in addition to magnetic particles in coating  310 , it may be possible to include magnetic particles  302 A- 302 N throughout the volume formed between the external and internal surfaces of tube  306 , similar to the example of  FIG. 3A . 
     Accordingly, this disclosure describes examples of a hearing assistance device that includes an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user when the hearing assistance device is worn. Examples of the enclosing structure include behind-ear portion  106 A for BTE or in-ear portion  108  for IIC, CIC, MIC, MIH, or ITE. 
     The hearing assistance device also includes a tube (e.g., tube  300 ) coupled to the receiver to direct the sound waves into the ear canal of the user. Tube  300  comprises magnetized particles  302 A- 302 N that form a magnetic field through the tube  300 . Tube  306  includes magnetized particles in coating  310  that form a magnetic field through tube  306 . 
       FIG. 4  is a block diagram illustrating an example of a tube of a hearing assistance device immersed in a magnetic field.  FIG. 4  illustrates tube  400 . Tube  400  may be substantially similar, including identical, to any one or combination of tubes  110 , a tube having surface  200 , tube  300 , or tube  306  described above. 
     As illustrated in  FIG. 4 , the enclosing structure (e.g., behind-ear portion  106 A for BTE or in-ear portion  108  for IIC, CIC, MIC, MIH, or ITE) includes drive circuit  402  and coiled wire  404 . As illustrated, coiled wire  404  is external and not coupled to tube  400 . Although shown as being below tube  400 , in some examples, coiled wire  404  may be above tube  400  or at any other location generally proximate to tube  400 . 
     Coiled wire  404  may be coiled around (e.g., encircle) a core external to tube  400 . In  FIG. 4 , coiled wire  404  is coiled in air (e.g., the core is air); however, other types of cores may be used. As one example, the core may be silicon steel. 
     Drive circuit  402  may be configured to output an alternating current through coiled wire  404 . For example, coiled wire  404  may be configured to carry any alternating current. The alternating current flowing through coiled wire  404  causes an electro-magnetic field  408  to emanate from coiled wire  404 . In some examples, the amplitude of the alternating current is approximately in range of 200 mA to 500 mA such as when external to the user (e.g., on charging station) or approximately in range of 0.1 mA to 7 mA such as when the user is wearing the hearing assistance device. 
     In some examples, the amplitude of the alternating current may be based on various factors such as the rail voltage of drive circuit  402 , the type of power converter (e.g., buck converter or charge pump) used by drive circuit  402 , and the duty cycle of the current output by drive circuit  402 . The rail voltage may be based on the type of battery used for drive circuit  402 . For example, zinc air batteries provide 0.9 V to 1.3 V, lithium ion rechargeable batteries provide 1.2 V to 2.5 V, and in some examples, provide up to 3.6 V. The type of power converter may affect the peak electrical current and duty cycle before brown-out artifacts occur. 
     In some examples, the range of the amplitude may be 200 mA to 700 mA, over a 2 to 10 microsecond period, with a frequency of 0.2 Hz to 0.067 Hz (e.g., every 5 second to 15 second interval), such as 500 mA, over 5 microsecond period with a frequency of 0.1 Hz (e.g., every 10 second interval). Utilizing such example ranges for current amplitude and duration may allow jostling the ionic flow of the foreign material with a quick electromagnetic field and keep the foreign material from further ingress without applying a constant electrical current. The above ranges are provided merely as examples and should not be considered limiting. The range may be less than or greater than 200 mA to 700 mA, the duration of the current may be longer than or shorter than 2 to 10 microseconds, and the interval between which the current is delivered may be longer than or shorter than 5 to 15 seconds. 
     In some examples, the range of the amplitude of the current may be 0.1 mA to 7 mA, as described above. In such examples, the duration of the current may be from 2 to 10 microseconds, but may be longer or shorter as well. Also, the interval between which the current is delivered may be 5 to 15 seconds, but may be longer or shorter as well. 
     As described above, although water may flow through paths with reduced or no magnetic field, when water does enter a magnetic field, the dipole structure of water causes the water to reorient. For example, when the molecules reorient, this change makes the hydrogens turn parallel and perpendicular between magnetic and electromagnetic fields. Since hearing assistance devices have gotten more complex with wireless and stronger digital signal processors (DSPs) and are already frequently in magnetic fields, modifying or making programs to run circuits like this to generate magnetic fields can be implemented in hearing assistance devices. In some examples, the creation of the magnetic field may be timed with a low frequency sound wave. 
     The result of the reorientation may be that the cohesive forces of the foreign material are reduced making it easier to expel the foreign material. 
     In some examples, energy source  406  may be used to expel the foreign material. Energy source  406  is not required in every example. In the example illustrated in  FIG. 4 , energy source  406 , coiled wire  404 , and drive circuit  402  are within the enclosing structure. Therefore, the foreign material, when expelled may enter the ear canal of the user. However, the amount of foreign material may not be sufficiently large to negatively impact the user. 
     As one example, energy source  406  may be a structure that generates a force to expel the foreign material from tube  400 . For example, energy source  406  may generate a vibrating force that causes tube  400  to vibrate. The vibration causes the foreign material to vibrate and shake down towards the ear canal and out of tube  400 . Another example of the force is an audio signal that pushes the foreign material. For instance, energy source  406  may be the receiver that generates an audio signal that is inaudible to the user but has sufficient force to move the foreign material. Energy source  406  may be configured to provide both vibration and audio signal that is inaudible, as two non-limiting examples of force, to expel the foreign material. 
       FIG. 5  is a block diagram illustrating another example of a tube of a hearing assistance device immersed in a magnetic field.  FIG. 5  illustrates tube  500  which may be similar, including identical, to any one or combination of tube  110 , a tube formed by surface  200 , tube  300 , or tube  400 . 
     The example illustrated in  FIG. 5  is similar to the example illustrated in  FIG. 4 , except coiled wire  504  is coiled around (e.g., encircles) tube  500 , and in contrast, coiled wire  404  is external and separate from tube  400 . 
     As illustrated in  FIG. 5 , the enclosing structure (e.g., behind-ear portion  106 A for BTE or in-ear portion  108  for IIC, CIC, MIC, MIH, or ITE) include drive circuit  502  and coiled wire  504 . Unlike coiled wire  404 , coiled wire  504  may be coiled around tube  500 . 
     Drive circuit  502  may be configured to output an alternating current through coiled wire  504 . For example, coiled wire  504  may be configured to carry an alternating current. The alternating current flowing through coiled wire  504  causes an electro-magnetic field  508  to emanate from coiled wire  504 . In some examples, the amplitude of the alternating current is approximately in range of 200 mA to 500 mA such as when external to the user (e.g., on charging station) or approximately in range of 0.1 mA to 7 mA such as when the user is wearing the hearing assistance device. Similar to above, electro-magnetic field  508  may reorient the water molecules to reduce the cohesive forces of the foreign material. 
     In some examples, energy source  506  may be used to expel the foreign material. Energy source  506  is substantially similar, including identical, to energy source  406 . 
     Accordingly, this disclosure describes examples of a hearing assistance device that includes an enclosing structure configured to house a receiver that generates sound waves into an ear canal of a user when the hearing assistance device is worn. Additionally, the hearing assistance device also includes a tube coupled to the receiver to direct the sound waves into the ear canal of the user. The hearing assistance device also includes a coiled wire (e.g., coiled wire  404  or  504 ) configured to carry an alternating current to generate an electro-magnetic field through tube  400  or  500 . 
       FIGS. 1A-1D and 2-5  illustrate different examples of tubes that are used in hearing assistance devices and different configurations of hearing assistance devices. These examples may be implemented separately or in combination. For example,  FIGS. 3A-3C  illustrate tube  300  that includes magnetized particles  302 A- 302 N that form a magnetic field through the tube (magnetic fluid may be used instead of or in addition to magnetized particles  302 A- 302 N).  FIG. 3D  illustrates tube  306  that includes coating  310  having magnetized particles similar to (including same as) magnetized particles  302 A- 302 N. In some examples, the internal surface of tube  300  or tube  306  may be the same as surface  200  of  FIG. 2 . However, the example techniques do not require the internal surface of tube  300  or tube  306  to be the same as surface  200 . 
     As another example, the examples of  FIG. 4  and/or  FIG. 5  may be used in combination with the example of  FIGS. 3A-3D . For instance, tube  400  or tube  500  may be formed in the same way as tube  300  or tube  306 . However, the example techniques do not require tube  400  and tube  500  to be formed in the same way as tube  300  or tube  306 . 
     As another example, tube  400  or tube  500  may include an internal surface similar to surface  200 . However, the example techniques do not require tube  400  or tube  500  to include an internal surface similar to surface  200 . 
     It is to be recognized that depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially. 
     In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over, as one or more instructions or code, a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processing circuits to retrieve instructions, code and/or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium. 
     By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, cache memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection may be considered a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non-transitory, tangible storage media. Combinations of the above should also be included within the scope of computer-readable media. 
     Functionality described in this disclosure may be performed by fixed function and/or programmable processing circuitry. For instance, instructions may be executed by fixed function and/or programmable processing circuitry. Such processing circuitry may include one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor,” as used herein may refer to any of the foregoing structures or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules. Also, the techniques could be fully implemented in one or more circuits or logic elements. Processing circuits may be coupled to other components in various ways. For example, a processing circuit may be coupled to other components via an internal device interconnect, a wired or wireless network connection, or another communication medium. 
     Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, various units may be combined in a hardware unit or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.