HAC Hearing Aid Fitting & Adjustment 3 — Questions and Answers
Question 1: Which compression parameter determines the input level at which the hearing aid transitions from linear to compressed amplification?
- Compression ratio
- Kneepoint (compression threshold) (Correct answer)
- Attack time
- Release time
Correct answer: Kneepoint (compression threshold)
The kneepoint (or compression threshold) is the input SPL level above which compression begins to reduce gain.
Question 2: A dispensed BTE hearing aid produces occlusion effect complaints. The patient says their own voice sounds 'boomy.' What is the best solution?
- Use a closed dome to increase the seal
- Switch to an open-fit or vented earmold (Correct answer)
- Increase low-frequency gain
- Enable the telephone program
Correct answer: Switch to an open-fit or vented earmold
An open fitting or vented earmold allows low-frequency energy from the patient's own voice to escape rather than resonating in the occluded canal.
Question 3: What is the recommended maximum output (OSPL90) verification procedure to ensure the hearing aid will not cause loudness discomfort?
- Compare OSPL90 to the patient's uncomfortable loudness level (UCL) (Correct answer)
- Set OSPL90 to the patient's pure-tone average
- Measure OSPL90 only in a sound booth
- Verify OSPL90 equals the hearing threshold level
Correct answer: Compare OSPL90 to the patient's uncomfortable loudness level (UCL)
OSPL90 should be set so that the maximum output does not exceed the patient's UCL, protecting against uncomfortable loudness or further hearing damage.
Question 4: Which feature allows a hearing aid to automatically switch programs based on the acoustic environment?
- Manual volume control
- Automatic environment classification (Correct answer)
- Directional microphone toggle
- Tinnitus masker
Correct answer: Automatic environment classification
Automatic environment classification uses signal processing algorithms to detect acoustic scene characteristics and seamlessly switch to the most appropriate program.
Question 5: When verifying a hearing aid with probe-microphone measures, the probe tube should be positioned approximately how far from the eardrum?
- 2 mm
- 5 mm
- 28 mm from the tragus notch (Correct answer)
- Flush with the canal entrance
Correct answer: 28 mm from the tragus notch
Positioning the probe tube approximately 28 mm from the tragus notch (about 5 mm from the eardrum) ensures accurate measurement of SPL near the tympanic membrane.
Question 6: A patient with bilateral moderate sensorineural hearing loss prefers the left ear hearing aid louder than the right, even though thresholds are symmetric. What should the fitter do?
- Automatically mirror left settings to right
- Adjust right ear gain upward to match left
- Investigate for asymmetric word recognition scores before adjusting (Correct answer)
- Program both ears identically regardless of preference
Correct answer: Investigate for asymmetric word recognition scores before adjusting
Asymmetric preference despite symmetric thresholds may indicate a difference in word recognition, tolerance, or ear canal acoustics that should be evaluated before changing gain.
Question 7: What term describes the hearing aid's ability to reduce the gain applied to loud sounds while maintaining audibility of soft sounds?
- Frequency compression
- Wide dynamic range compression (WDRC) (Correct answer)
- Peak clipping
- Frequency transposition
Correct answer: Wide dynamic range compression (WDRC)
WDRC applies high gain to soft sounds and progressively lower gain to loud sounds, fitting more of the dynamic range of speech into the patient's residual hearing range.
HAC Hearing Aid Fitting & Adjustment 3
Which compression parameter determines the input level at which the hearing aid transitions from linear to compressed amplification?