Quantifying the Range of Signal Modification in Clinically Fit Hearing Aids.
Varsha Rallapalli, Melinda Anderson, James Kates and 4 others
PMID 31408045WHAT IT FOUND
Clinically fit hearing aids changed speech signals over a range from 0.36 to 0.94 on a scale where 1 means least change.
The change was greater in noisier and louder conditions, differed by manufacturer, and was not explained by premium versus basic technology.
Key findings
01Across clinically fit hearing aids, average signal modification ranged from 0.36 to 0.94 on a 0 to 1 scale where 1 means least modification.
02Signal modification increased as background noise worsened and input level rose, and the pattern differed by manufacturer.
03Premium versus basic hearing aid technology did not have a significant effect on signal modification.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study measured hearing-aid output only; it did not test whether patients understood speech better or preferred the sound. Only the right ear was used, so binaural effects and ear-to-ear wireless noise reduction were not captured. Speech and babble came from the same direction, so directional microphones may not have been evaluated. Only speech in quiet and in babble was used, so music and environmental noise were not covered. Custom mold fittings were excluded, so results may not apply to fully custom devices. Six receiver-in-the-canal models from three manufacturers were studied, so other devices and styles were not tested.
Declared interests
The authors declared no conflicts of interest. The supplied text does not report funding.
The easy way to misread this
Do not treat the 0.36 to 0.94 range as proof that some hearing aids will sound better or worse to patients. The study measured hearing-aid output only and did not test listening outcomes.