Acoustic reflexes are common but not pervasive: evidence using a diagnostic middle ear analyser.
Kara D McGregor, Gregory A Flamme, Stephen M Tasko and 4 others
PMID 29256642WHAT IT FOUND
Acoustic reflexes are common but not pervasive in young adults with excellent hearing.
No subgroup reached the threshold for 95% prevalence, even when using a stable friction-fit probe. Damage-risk criteria should not assume everyone will exhibit this reflex.
Key findings
01No participant group met the statistical criterion for acoustic reflex pervasiveness (lower bound of 90% confidence interval exceeding 0.95).
02Even in the most favorable subgroup (ages 18–30 with excellent hearing), acoustic reflex prevalence did not reach the pervasiveness threshold.
03Acoustic reflex prevalence was consistently lower for contralateral stimulation than for ipsilateral stimulation across all frequencies.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat 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 population was heavily skewed toward young adults (median age 21) and females (70%), which likely overestimates the prevalence of acoustic reflexes compared to the general population. The study used long-duration tonal elicitors, which do not mimic the short-duration impulsive sounds (like gunshots or explosions) relevant to damage-risk criteria. Broadband noise elicitors were not tested, which might have yielded different prevalence rates. The definition of 'pervasive' (95% prevalence) is a strict statistical threshold; the reflex is common (>90%) but fails this specific criterion.
Declared interests
The authors have no conflicts to declare. The study was supported by U.S. Government research funding.
The easy way to misread this
Do not interpret the high prevalence rates (over 90%) as evidence that acoustic reflexes are pervasive. The study explicitly defines 'pervasive' as having a lower confidence bound above 95%, and no group met this criterion. Additionally, do not assume these results apply to impulsive noise; the study used long-duration tones, and the authors state that reflexes to tones do not guarantee reflexes to impulses.