IHS Instrument Fitting 3 — Questions and Answers
Question 1: During earmold impression taking, the cotton or foam dam is placed in the ear canal to:
- Reduce patient discomfort
- Protect the tympanic membrane from impression material (Correct answer)
- Improve acoustics of the impression
- Keep the ear canal dry
Correct answer: Protect the tympanic membrane from impression material
The dam acts as a barrier to prevent impression material from contacting or damaging the tympanic membrane.
Question 2: Which hearing aid style is most appropriate for a patient with severe-to-profound hearing loss who also has chronic ear drainage?
- In-the-canal (ITC)
- Completely-in-canal (CIC)
- Behind-the-ear (BTE) with earmold (Correct answer)
- In-the-ear (ITE)
Correct answer: Behind-the-ear (BTE) with earmold
BTE with earmold keeps the electronics away from the moist ear environment, making it suitable for patients with ear drainage.
Question 3: What is the primary purpose of a damper placed in the sound bore of an earmold?
- Increase overall gain
- Smooth peaks in the frequency response (Correct answer)
- Reduce low-frequency output
- Prevent moisture entry
Correct answer: Smooth peaks in the frequency response
Dampers reduce resonance peaks in the frequency response, creating a smoother, more natural sound quality.
Question 4: A receiver-in-canal (RIC) hearing aid is preferred over a standard BTE for mild-to-moderate loss primarily because it:
- Provides more gain
- Has a larger battery
- Reduces the occlusion effect and improves high-frequency response (Correct answer)
- Is more durable
Correct answer: Reduces the occlusion effect and improves high-frequency response
Placing the receiver in the ear canal allows for an open fitting, reducing occlusion and improving high-frequency delivery.
Question 5: When fitting binaural hearing aids, the primary audiological benefit compared to monaural fitting is:
- Doubled gain output
- Improved sound localization and speech in noise (Correct answer)
- Reduced feedback
- Longer battery life per device
Correct answer: Improved sound localization and speech in noise
Binaural fitting allows the brain to use interaural time and level differences, improving localization and speech understanding in noisy environments.
Question 6: Which coupler is used as the standard reference cavity for measuring hearing aid output in a test box?
- 0.6-cc coupler
- 2-cc coupler (Correct answer)
- Zwislocki coupler
- Ear simulator coupler
Correct answer: 2-cc coupler
The 2-cc coupler (HA-1 or HA-2) is the industry-standard reference cavity for measuring hearing aid electroacoustic characteristics.
Question 7: A patient's hearing aid produces an acoustic feedback whistle only when they cup their hand near the ear. The MOST likely cause is:
- Earmold is too tight
- Insufficient vent size
- Inadequate feedback suppression for reflected sound (Correct answer)
- Battery voltage too low
Correct answer: Inadequate feedback suppression for reflected sound
Cupping the hand reflects amplified sound back into the microphone; if feedback suppression cannot cancel this rapidly enough, oscillation occurs.
IHS Instrument Fitting 3
During earmold impression taking, the cotton or foam dam is placed in the ear canal to: