Normative Study of the Binaural Interaction Component of the Human Auditory Brainstem Response as a Function of Interaural Time Differences.
Carol A Sammeth, Nathaniel T Greene, Andrew D Brown and 1 others
PMID 33141776WHAT IT FOUND
A brainstem binaural response (BIC) was measurable in most normal hearing adults, but only 39 of 40 in at least one session and only 46% in both sessions.
It did not match behavioral time-difference thresholds, so it does not support current clinical use.
Key findings
01A BIC DN1 was identified at ITD = 0 in 39 of 40 subjects in at least one session, but only 46% produced one across both sessions.
02BIC DN1 latency increased with ITD, and relative BIC amplitude decreased with increasing ITD.
03BIC measures did not correspond with behavioral ITD discrimination thresholds.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
All subjects were normal hearing adults aged 21 to 48 years, so it does not show how the BIC behaves in children, older adults, or people with hearing loss or auditory processing disorder. Only 46% of subjects produced an identifiable BIC at ITD = 0 across both sessions, and fewer produced it at larger ITDs, so the measure was not consistently reliable. The BIC did not correspond with behavioral ITD discrimination thresholds, so the study does not establish that it measures the same binaural ability as the behavioral task. Muscle artifact and movement were major reasons the BIC was poor or absent, and measurement required long sessions and very many click repetitions. The study was not a diagnostic accuracy study in patients, so it cannot tell clinicians whether the BIC identifies binaural hearing problems in practice.
Declared interests
The supplied metadata indicates NIH extramural research support. No author conflict-of-interest declaration is included in the article text.
The easy way to misread this
Do not conclude that the BIC is a ready clinical biomarker for binaural hearing problems. It was not identifiable in all normal hearing adults, it became less common at larger ITDs, and it did not correspond with behavioral ITD discrimination thresholds.