HAC HAC Earmold Selection & Hearing Aid Styles 2 — Questions and Answers
Question 1: Which materials are most commonly used to fabricate custom hearing aid earmolds?
- Acrylic (hard) or silicone (soft) (Correct answer)
- Titanium or stainless steel
- Polyurethane open-cell foam
- Natural rubber latex
Correct answer: Acrylic (hard) or silicone (soft)
Custom earmolds are typically made from hard acrylic or soft silicone, with the choice based on retention requirements, comfort preferences, and acoustic needs.
Question 2: Why is an ear impression taken before fabricating a custom hearing aid or earmold?
- To measure the patient's hearing thresholds
- To capture the exact shape of the ear canal and concha so a precisely fitting shell or mold can be manufactured (Correct answer)
- To assess eustachian tube function
- To determine the correct hearing aid battery size
Correct answer: To capture the exact shape of the ear canal and concha so a precisely fitting shell or mold can be manufactured
An ear impression creates a physical replica of the ear canal and concha, which is used as the model for manufacturing a custom-fit earmold or hearing aid shell.
Question 3: What is an open-fit dome in a RIC or slim-tube BTE hearing aid?
- A fully occluding earmold with no vent holes
- A small non-occluding tip that leaves much of the ear canal open, minimizing the occlusion effect (Correct answer)
- An earmold made of open-cell foam material
- A vented shell for profound hearing loss fittings
Correct answer: A small non-occluding tip that leaves much of the ear canal open, minimizing the occlusion effect
An open-fit dome leaves the ear canal largely unoccluded, reducing the occlusion effect and making it suitable for patients with normal or near-normal low-frequency hearing.
Question 4: Which earmold style provides the most retention and acoustic seal, making it suitable for severe-to-profound hearing loss?
- Canal-only earmold
- Skeleton earmold
- Full shell (concha fill) earmold (Correct answer)
- Half-shell earmold
Correct answer: Full shell (concha fill) earmold
A full shell earmold fills the entire concha bowl, providing maximum surface contact for retention and a secure acoustic seal essential for high-power fittings.
Question 5: What does a CROS hearing aid system do?
- Provides binaural amplification for symmetrical bilateral hearing loss
- Routes sound picked up at a non-aidable ear to a hearing aid worn on the better ear for unilateral hearing loss (Correct answer)
- Programs cochlear implant speech processors
- Delivers bone-anchored amplification for bilateral conductive loss
Correct answer: Routes sound picked up at a non-aidable ear to a hearing aid worn on the better ear for unilateral hearing loss
A CROS (Contralateral Routing of Signal) system transmits sound from the poorer ear's microphone wirelessly to a receiver worn on the better ear.
Question 6: How does a longer canal portion of an earmold affect feedback susceptibility?
- It increases feedback by moving the receiver farther from the eardrum
- It reduces feedback by providing a deeper, tighter acoustic seal in the canal (Correct answer)
- Canal length has no measurable effect on feedback
- Shorter canal lengths always reduce feedback
Correct answer: It reduces feedback by providing a deeper, tighter acoustic seal in the canal
A longer canal portion creates a better acoustic seal deeper in the ear canal, reducing the likelihood that amplified sound will leak back to the microphone and cause feedback.
HAC HAC Earmold Selection & Hearing Aid Styles 2
Which materials are most commonly used to fabricate custom hearing aid earmolds?