The Medial Olivocochlear Reflex Is Unlikely to Play a Role in Listening Difficulties in Children.
Sriram Boothalingam, Chris Allan, Prudence Allen and 1 others
PMID 31558110WHAT IT FOUND
Children referred for listening difficulties had similar strength of a brainstem ear reflex to typical peers on several ear-canal sound tests.
This does not support that reflex as a common explanation for their speech-in-noise complaints.
Key findings
01The reflex measured from the same ear, the opposite ear, and both ears did not differ between children with listening difficulties and typical children.
02Reflex strength measured with click-evoked, stimulus-frequency, and distortion-product emissions did not differ between groups.
03Children with listening difficulties who did and did not meet auditory processing disorder criteria showed no difference in reflex inhibition.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Final analysed numbers varied by emission test after exclusions, so the groups were not identical across all measures. 17 children from the listening-difficulty group and 3 typical children were rejected in Study 2, mainly because of noise or inability to sit quietly. Only one ear was tested per child, so the study cannot address left-right asymmetry findings reported in some earlier work. Typical children did not receive the auditory processing disorder battery, so it is possible some had undetected test failures. The listening-difficulty group was heterogeneous: some met auditory processing disorder criteria and some did not, and they failed different tests. The reflex methods have known variability and imperfect reliability, and middle-ear-reflex control cannot be considered perfect.
Declared interests
Funded by Western Graduate Research Scholarship, Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, and Ontario Research Fund. No author conflicts are reported.
The easy way to misread this
Do not conclude that children's listening difficulties are not real or have no auditory basis. The study only failed to find a group difference in a brainstem ear reflex, and the authors note that other auditory or non-auditory factors may explain the complaints.