IHS Instrument Fitting 2 — Questions and Answers
Question 1: Which real-ear measurement (REM) target is most commonly used when fitting hearing aids to adults using evidence-based best practices?
- NAL-NL2 (Correct answer)
- COSI
- APHAB
- DPOAE
Correct answer: NAL-NL2
NAL-NL2 (National Acoustic Laboratories Non-Linear version 2) is a widely adopted prescriptive target for fitting hearing aids in adults.
Question 2: When performing a real-ear aided response (REAR) measurement, the probe microphone is placed:
- At the entrance to the ear canal
- Approximately 5–6 mm from the eardrum (Correct answer)
- Behind the pinna
- At the tip of the earmold
Correct answer: Approximately 5–6 mm from the eardrum
The probe tube is inserted to approximately 5–6 mm from the tympanic membrane to accurately capture the sound at the eardrum.
Question 3: A patient reports that soft speech sounds are inaudible even at maximum volume. The MOST likely fitting issue is:
- Compression ratio set too high
- Insufficient gain for soft inputs (Correct answer)
- Excessive high-frequency gain
- Feedback suppression over-activation
Correct answer: Insufficient gain for soft inputs
Insufficient gain for soft-level inputs means quiet sounds are not amplified enough to reach audibility.
Question 4: The DSL m[i/o] prescriptive method was specifically developed for:
- Adults with sensorineural hearing loss
- Pediatric populations and infants (Correct answer)
- Patients with conductive hearing loss only
- Unilateral hearing loss fittings
Correct answer: Pediatric populations and infants
DSL m[i/o] (Desired Sensation Level) was designed to optimize audibility of speech for children, including infants.
Question 5: Which term describes the maximum output of a hearing aid regardless of input level?
- AGC threshold
- OSPL90 (Correct answer)
- MPO target
- Saturation SPL
Correct answer: OSPL90
OSPL90 (Output Sound Pressure Level at 90 dB input) is the standardized measure of a hearing aid's maximum output.
Question 6: A first-time hearing aid user complains that their own voice sounds hollow or like they are talking in a barrel. This is most likely caused by:
- Insufficient low-frequency gain
- The occlusion effect (Correct answer)
- Feedback cancellation
- Excessive compression
Correct answer: The occlusion effect
The occlusion effect occurs when a closed earmold blocks the ear canal, amplifying bone-conducted low-frequency energy of one's own voice.
Question 7: To reduce the occlusion effect without sacrificing low-frequency amplification for a patient with a sloping high-frequency loss, the best earmold modification is:
- Increase vent diameter (Correct answer)
- Add a longer canal portion
- Switch to a power earmold
- Reduce earmold thickness
Correct answer: Increase vent diameter
Increasing the vent diameter allows low-frequency bone-conducted sound to escape, reducing the hollow sensation without affecting amplification for patients who do not need low-frequency gain.
IHS Instrument Fitting 2
Which real-ear measurement (REM) target is most commonly used when fitting hearing aids to adults using evidence-based best practices?