Earmolds Flashcards
An earmold that fills the entire concha bowl and canal portion is what type and what type of HL do these suit
Shell earmold and suits severe to profound HL as it seals the canal and outer ear
Resemble a shell but only fill the bottom half of the ear. What type of mold?
Half Shell
Which type of earmold outlines the rim of the outer ear while effectively sealing the canal.
Skeleton EM AKA Phantom or silhouette EM
What type of HL does a Skeleton EM suit
Moderate to moderately severe HL
Occurs when air is enclosed in an earmold with rigid walls
Acoustic Compliance
Highly compliant Earmolds aid the transmission of which sounds
HF sounds
When the volume of air increases by Belling canal or shortening a earmold, compliance increases
The Horn Effect
What type of losses require less material in the aperture and intertragal notch area, retaining a natural ear canal resonance
More mild HL’s
What kind of vent opens up the canal on a shell, skeleton or canal earmold, creating a non-occluding earmold
Parallel Vent
What are some features of a parallel vent
More and more canal resonance naturally occurs depending on size of vent
Low Frequencies bleed off through the opening emphasizing higher frequencies and affecting both gain and output by a few dB
Occurs when a volume of air oscillated with compressing to any significant extent, as in tubing or a bore at a vent
Acoustic Inertance
Which vents bleed off only extreme lows, and may include more than one vent when necessary
Angle or Diagonal Vents
What are some features of an external vent
Reduces the fullness or occlusion rather than fulfilling an acoustic modification.
Mostly often used to solve a problem on an unvented ITE or canal instrument.
The gain and output of any HA increase or decreases by changing what
Changing tube diameter
What kind of tubing should you use if feedback is a problem or if fitting is tubing only
Heavy Wall Tubing
What is the purpose of using dampers, filters or lambs wool in the tubing
Restrict the acoustic flow across frequencies. Based on position of filter or damper in the HA earhook or EM determines the frequency response change.
What are some deciding factors when choosing Earmold materials?
Power level requirements, patient dexterity, ear texture, allergy problems and cosmetic appeal
What are some benefits when using Lucite (acrylic) EM
Ease of modification, maintenance, durability, and cosmetic appeal
Which EM material is best to use when allergy is an issue?
Polyethylene, a semi rigid white material resembling paraffin wax
Which EM material is best to use when power is a requirement
Silicone
When performing an impression, why is it important to stay buried in the impression material?
To prevent air pockets, cracks, lines or bubbles nor will you have distorted the ear with any manual pressure
When the mold exceeds past the second bend what is eliminated and increased
Occlusion effect is eliminated and intensity doubles as the distance to the Ear drum is shorter
When using the syringe method, what should you do to prevent air pockets, cracks, lines or bubbles
Keep the tip of the syringe buried in the impression material while taking the impression—-this is the opposite for Gun method
Longer earmold canal increases what? And Shorter decreases what?
Response Curve
If a pt is complaining of their own voice, background noise, car noise, full ear or harshness of other peoples voice along with when they chew what should be done
Larger vent is needed
A small pressure vent (0.020 to 0.030) in an earmold will
Have little or no effect on frequencies above 400 Hz
Generally reduce levels at frequencies below 200 Hz
Reduce atmospheric pressure build up
A long canal on the earmold has the effect of
Accentuating the low frequencies
Venting an Earmold
Is the most common modification made on an earmold
The non-occluding earmold is excellent to use on
A CROS fitting
Earmold have two important parts
Outer appearance and canal acoustics
The greatest acoustic change in an earmold or ITE is
Parallel venting
The greatest deciding factors in material selection for an earmold are
Power requirements
To shift the resonant peak upward between 1500-3000 Hz use
Larger bore diameter
In general, mold modifications are as follows
Venting affects lows, damping the midrange and horn effects boost highs
Which molds have the same outer appearance
Skeleton and 2 HF
