Discrimination of Gain Increments in Speech.
Benjamin Caswell-Midwinter, William M Whitmer
PMID 31736405WHAT IT FOUND
Small overall gain changes to speech can be noticed, but frequency-specific changes are much harder to hear.
Patients may not notice small hearing-aid fine-tuning changes, especially at high frequencies. This is not evidence that changes improve outcomes.
Key findings
01Broadband gain changes were easier to detect than octave-band or dual-band gain changes.
02High-frequency gain changes were harder to detect than low- and mid-frequency changes.
03High-frequency detection was related to high-frequency pure-tone thresholds and sensation level.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used recorded male sentences in quiet, not real hearing-aid use in everyday environments. Adjustments were made in octave and dual-octave bands, not the narrower bands used by modern hearing aids; narrower changes are expected to be harder to detect. Participants were tested only in their better ear, so results may not apply to poorer ears or bilateral use. Five JNDs, approximately 2% of the total, were excluded because the data fit poorly. Individual differences were large, so a median threshold is not enough to predict what one patient will notice. The study did not test whether these thresholds change over time or affect intelligibility, preference, or sound quality.
Declared interests
The Medical Research Council and the Chief Scientist Office funded the work. The supplied text gives no author conflict-of-interest declaration.
The easy way to misread this
Do not treat these thresholds as universal hearing-aid fitting targets. The study used recorded male sentences, octave and dual-octave bands, and quiet listening, so real-world adjustments and narrower bands may be harder to notice.