Unilateral Acoustic Degradation Delays Attentional Separation of Competing Speech.
Frauke Kraus, Sarah Tune, Anna Ruhe and 2 others
PMID 34184964WHAT IT FOUND
When the attended speech was degraded, 22 normal-hearing adults answered fewer content questions correctly and the brain response that picked out the target voice appeared later.
This does not show a clinical fix for cochlear implant users.
Key findings
01When the attended speech was degraded, correct answers averaged 0.82 of content questions, compared with 0.92 when the attended speech was clear; chance was 0.25.
02Using the whole neural response model, attention enhanced tracking of clear and degraded target speech to similar extents.
03The attentional enhancement was delayed for degraded speech: stronger for clear speech at 144 to 192 ms and stronger for degraded speech at 312 to 336 ms.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The participants were 22 young normal-hearing adults, not unilateral cochlear implant users. Two participants had hearing loss of up to 40 dB HL at some frequencies on the right side, but their data were kept because their overall performance was good. The degraded speech was a laboratory simulation, not an actual cochlear implant, and participants had no prior adaptation or training with degraded speech. The authors say the results should be transferred to actual unilateral cochlear implant users with caution. The headphone presentation placed competing speech at 90 degrees to either side, which is rare in real life and did not allow the two sounds to mix naturally before entering the ears. The statistical test used here does not establish the exact start and end times of the delayed attentional effect. The study did not test whether delayed attentional selection causes poorer speech comprehension in real patients.
Declared interests
The authors declared no potential conflicts of interest. The funding section reports financial support from Cochlear Inc.
The easy way to misread this
Do not read this as proof that unilateral cochlear implant users have a delayed attentional mechanism in everyday listening. The study tested 22 young normal-hearing adults with simulated degraded speech through headphones, and the authors state that results should be transferred to actual unilateral cochlear implant users with caution.