Olivocochlear Efferent Activity Is Associated With the Slope of the Psychometric Function of Speech Recognition in Noise.
Ian B Mertes, Erin C Wilbanks, Marjorie R Leek
PMID 29135685WHAT IT FOUND
At a fixed noise level, brain-to-ear feedback activity was not linked to word or sentence recognition.
In this small lab study, stronger feedback activity was linked to greater improvement in recognition as the noise became less severe.
Key findings
01Contralateral suppression was not significantly correlated with speech recognition at a fixed noise level.
02Contralateral suppression was significantly correlated with the slope of performance across noise levels for each test.
03The slope correlations were positive, meaning larger contralateral suppression was associated with steeper performance gains as the noise level improved.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only 15 of 16 participants were analyzed, so the correlations are unstable and could change with more data. The sample was mostly older men from a Veterans Affairs clinic, and many had mild high-frequency hearing loss, so it may not apply to younger or more severely impaired patients. The speech tasks were laboratory tests in fixed negative signal-to-noise ratios, not everyday listening. The study measured an association, not a cause, and contralateral suppression was measured through one pathway while speech was tested through the ipsilateral pathway. The analyses controlled for age and high-frequency thresholds, but the relationship may still differ in other hearing profiles.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that stronger efferent activity causes better speech recognition in noise at a fixed noise level. The correlations at each tested signal-to-noise ratio were not significant, and the study was correlational, so it cannot show causation or support a clinical treatment decision.