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The following data was collected during the stakeholder
forum and summarizes the comments of forum participants.
- Measurement process needs to be more comfortable for the client by reducing the time that the impression material is in place.
- Earmolds need to be flexible to accommodate changes in head position (tilting the head or when bending over; sitting upright or slouching), and jaw positions or movement (when talking, eating, or laughing).
- Earmold materials need to remain comfortable and unaffected by prolonged contact with the skin, skin oils, or earwax.
- Earmold material needs to remain flexible without hardening over time.
- Need earmolds that are easy to insert into the ear canal.
- Need to reduce/eliminate feedback.
- Need to provide the same quality of sound as a person that doesn't use a hearing aid.
- Need to improve earmold aesthetics by making them less obvious (e.g. smaller earmolds, materials that are clear and will more closely match the wearer's skin color)
Note:
smaller earmolds will impact other aspects of the hearing aid that
are more important to the user. For example, sound quality, keeping
the hearing aid securely in place, and placement of electronic components
within the hearing aid).
- Need to create an earmold that is disposable and low cost.
- Need to eliminate the need for earmolds all together.
- Need ear-hook dampers that do not clog, or are self-cleaning.
- Need to identify a method that accurately measures the shape of the ear canal without the use of casting materials.
- Need to measure points of increased pressure within the ear canal,
or areas that cause skin irritation. Allow measurements to be taken at
different parts of the ear.
- Need to improve the measurement process (more accurate) with standardized methods to reduce the chance of error during the initial casting of the mold, or when replacement earmolds are required.
- Need 3-D image of the ear canal. Images kept in an electronic file could be maintained indefinitely, unlike earmold impressions that are kept for a short period of time.
- Need casting materials that are comfortable to the client, yet is flexible enough to register accurate impressions and will not shrink between the times the impression is taken and the earmold are cast.
- Need casting material that remain fluid until it comes in contact with the ear canal where is sets quickly to reduce the chance of the material leaking out of the canal.
- Need earmolds that accurately fit within the ear canal and conform to changes within the ear throughout the day -- depending on the time of day and on jaw and body movements.
- Need earmold material that is biocompatible with the ear environment
over a long period of time. The ear recognizes an earmold as a foreign
object and tries to eject it by increasing the amount of earwax and skin
oils.
- Need earmold material that is stable for a long period of time; maintain its shape and hardness; does not absorb skin oils, earwax or water; and is non-irritating, non-allergenic, and resists bacteria.
- Need tubing materials that is compatible with the earmold and will not change color, shrink or deteriorate.
- Need to create same day production of the earmold to reduce impact caused by shrinkage that occurs between the time when the measurements are taken and the earmold is produced.
- Need to train technicians so that they employ consistent fitting methods - reduce irregular fittings regardless of the manufacturer.
- Need manufacturers to agree on consistent methods of production, and materials used for creating impressions and for the earmolds themselves.
- Need better communication between the clinician and consumer so they have realistic expectations of the process and end results of using a hearing aid.
- Need to work with other industries to increase the size of the market to increase the value of committing research and development efforts. The hearing industry itself is too small to justify large investments of time and resources.
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- Technology for the hearing industry has been transferred from the dental
industry, however material requirements for dental and hearing applications
differ. Earmold material (1) must be flexible and accommodate changes in the ear canal throughout the day. For example, after being worn a few hours, the earmold will cause the ear canal to stretch. (2) The ear canal is flexible, warm and moist and has many sharp angles and changes of direction. This same flexible material must provide a snug secure fit without causing irritation. (3)
Creating the earmold shape depends upon measurements where the clinician
cannot see the actual anatomy where the product will be used.
- Impressions are a static measurement (snapshot) while the ear canal
constantly changes in response to such factors as head position, jaw
movement, time of day when the impression is made, posture and whether
the person was wearing a hearing aid just prior to the measurements being
taken. Changing the position of the jaw can cause a variance in canal diameter of more than 30% depending upon whether the mouth is opened or closed. It
is best to make more than one impression.
- Casting material and impression making technique differs somewhat between
clinicians and from client to client. A technician's technique for making earmolds from these impressions depends upon who provides their training. "This process [from making the impression to a finished earmold] is considered by industry insiders as an "art form" rather than a science which cannot be repeated consistently. Ten
impressions [for the same client] made by ten clinicians would yield
ten very different earmolds.
- Casting material shrinks as it hardens. The length of time between when the impression is made by the clinician versus when the earmold is produced by the technician will vary greatly by days. The amount of shrinkage depends upon the time difference between measurement and production. For
this reason, it is unreasonable for the manufacturers to keep impressions
for an extended period of time and new impressions must be taken each
time the earmold is reproduced.
- Earmold material differs between manufacturers, with client needs,
and with the type of the hearing loss. Silicone, acrylics and polymers are examples of earmold materials used today. The
clinician may also prefer one material or another based upon their ability
to customize the earmold's shape after it has been cast.
- The body considers the earmold as a foreign body within the ear canal
and tries to remove it by increasing the production of oils or wax. In
addition, skin sensitivity is heightened with a foreign body in place.
Improper measurements (or earmolds that change physical characteristics
over time) may cause irritation and soreness that may result in the hearing
aid not being used.
- Earmolds have an average lifespan of about two years. (Earmold lifespan among forum participants ranged from three months to thirteen years.) Earmold lifespan is dependent upon changes to the ear canal (e.g. canal growth in a young child); by the materials used (e.g. polymers have a relatively short lifespan and quickly discolor from skin oils and earwax); by how well the earmold is maintained (cleaning), and by changes to client's audiogram (requiring a different earmold).
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- Automate and standardize the process by which earmolds are produced.
Eliminate variability in methods and materials starting with the fitting
process through to the finished product. Eliminate the "art" of creating an earmold. Computerized measurement of the ear canal. Create
3-D image and measurements (e.g. by using lasers, MRI or CAT scan etc.)
that can be transformed into a mathematical representation of the ear
canal and used to produce the earmold. This will ensure consistency in
measurements, eliminate errors caused by shrinkage, and provide a permanent
record of the impression to be kept on file.
- Rapid production of the earmold and hearing aid. One-day turn around
from measurement to use is ideal.
- Earmold material:
- Flexibility to adapt to dimensional changes within the ear (e.g. due to head position or movement)
- Long-term stability
- Not susceptible to oils and wax
- Will not shrink over time
- Does not induce increased oil and wax production
- Easy to clean
- Provide "self-disinfecting" characteristics when in contact
with open sores
- Specific earmold design suggestions included:
- Surround the earmold with a gel-like material that will "flex" with
changes that might occur within the ear canal while maintaining a
secure fit.
- A reverse thermal gel that hardens in the ear canal at body temperature (while remaining pliable for comfort) and softens at room temperature (for easy insertion).
- A "pneumatic earmold" that can be "pumped up" to
provide a secure fit and deflated for insertion or removal.
- Prefabricate earmolds in standard sizes and shapes. Each earmold fits a certain range of (ear canal) sizes and shapes. This
technology will enhance the development of disposable earmolds that
are less expensive to purchase and reduces the need for technician
related fittings after the initial measurements have been made.
An earmold that has similar properties/characteristics of a contact lens on the eye.
- An open earmold.
- Material that has a "chameleon-like" ability to adapt to
match the wearer's skin color -- similar to technology used with photo-gray
eye lenses.
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- The hearing aid market is not large enough to encourage investment in research and development efforts.
- Creating an "electronic" or 3-D image of the ear canal is
difficult because of hair, wax or other debris that may be a temporary
affect the shape and size of the ear canal.
- Participants are not aware of any materials suitable for making ear canal impressions that will not shrink.
- Participants are not aware of any materials suitable for making earmolds that have all of the desired characteristics.
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