Potential Destructive Binaural Interaction Effects in Auditory Steady-State Response Measurements.
Sam Watson, Søren Laugesen, Bastian Epp
PMID 34452588WHAT IT FOUND
Sound-field hearing aid verification using ASSR is generally robust if the child moves their head, but fails if a unilateral hearing aid introduces specific delays.
These delays can artificially suppress the response by 10 dB, leading to false referrals for poorly fitted aids.
Key findings
01Simulating a unilateral hearing aid delay that puts the 40 Hz response out of phase caused a significant 10 dB drop in ASSR power compared to the standard diotic condition.
02Simulating a child turning their head away from the speaker (changing the sound angle by 45 or 90 degrees) did not significantly change the ASSR, meaning the test remains valid despite head movement.
03When a unilateral hearing aid delay suppresses the response, it can make a good hearing aid fit look poor, potentially causing clinicians to refer patients for re-fitting unnecessarily.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study used normally hearing adults, not infants or children with hearing loss, so the exact magnitude of interference in the target population is unknown. The interference was only seen in a specific simulated delay condition; it is not known how common this exact delay is in real-world hearing aids. The 64-channel topography analysis had a very small sample size (6 subjects), limiting the certainty of the brain-mapping findings.
Declared interests
Part of the work was supported by the William Demant Fund. The authors declared no potential conflicts of interest.
The easy way to misread this
Do not assume that all unilateral hearing aid delays will cause this interference. The study only found significant suppression when the delay put the 40 Hz modulation specifically out of phase; other delays or head movements did not affect the result.