Age Effects on Cochlear Reflectance in Adults.
Sara E Fultz, Kenneth I Vaden, Daniel M Rasetshwane and 3 others
PMID 31369471WHAT IT FOUND
Cochlear reflectance changed with age mainly as hearing thresholds changed.
After accounting for thresholds, age effects were not seen except one frequency and level for magnitude.
Key findings
01Age effects adjusted for sex were significant at several frequencies, but after controlling for pure-tone threshold only cochlear reflectance magnitude at 5.7 kHz and 30 dB SPL remained significant.
02After adjusting for age effects, pure-tone threshold effects remained significant for cochlear reflectance magnitude at 1.4 and 2.0 kHz at all three stimulus levels and at 1.0 kHz at the highest stimulus level.
03After adjusting for age effects, pure-tone threshold effects remained significant for cochlear reflectance signal-to-noise ratio at 2.0 kHz for all stimulus levels, and at 1.4 and 8.0 kHz at the highest stimulus level.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study compared 60 adults in different age decade groups at one visit, not the same people followed over time. Age and pure-tone thresholds were correlated, so the analysis tried to separate their effects, but the design cannot prove which factor caused any change. High-frequency thresholds were not measurable in some participants because of equipment limitations, and missing thresholds were coded as 120 dB SPL. The test ear was biased toward the better hearing ear, and ear effects were not tested. The sample had normal middle ear status and ages 23 to 79 years, so it does not address children or people with middle ear disease. Many tests were performed within each frequency band and stimulus level, with corrections for multiple tests. The paper notes that low signal-to-noise ratio data from older adults contributed to significant results and that signal-to-noise ratio criteria can lower statistical sensitivity and distort effects. The supplied text does not report blinding, random allocation, or a pre-registered primary outcome.
The easy way to misread this
Do not conclude that cochlear reflectance declines independently with age. After adjusting for pure-tone thresholds, age effects were not significant except for cochlear reflectance magnitude at 5.7 kHz and 30 dB SPL.