Weakened Cochlear Nonlinearity During Human Aging and Perceptual Correlates.
Carolina Abdala, Amanda J Ortmann, Yeini C Guardia
PMID 33886169WHAT IT FOUND
Aging weakens cochlear compression even when hearing thresholds remain normal.
Older adults require louder sounds to trigger compression, resulting in steeper loudness growth and sounds being rated as loud at lower sensation levels. This suggests hidden cochlear changes drive loudness perception issues in aging.
Key findings
01Older adults show reduced distortion-product otoacoustic emission levels compared to young adults, particularly at high frequencies, even when hearing thresholds are matched.
02The compression knee of the cochlear response occurs at higher stimulus levels in older adults, indicating an expanded linear range and weakened nonlinearity.
03Older adults rate sounds as louder at lower sensation levels and show steeper loudness growth for soft tones, correlating with the elevated compression knee.
STILL TO COME
How it was doneWhat they foundWhat 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 is cross-sectional, so it cannot confirm that these changes occur within individuals over time. Ipsilateral suppression data had reduced observations in older adults because suppression was often not achieved, potentially biasing threshold estimates. The correlation between DPOAE metrics and loudness perception accounted for a modest amount of variance (one-third at best), indicating other factors also influence loudness judgment. Participants were selected for relatively good hearing, so findings may not generalize to those with significant hearing loss.
The easy way to misread this
Do not assume that normal hearing thresholds indicate normal cochlear function. Older adults can have significantly weakened cochlear nonlinearity and atypical loudness perception despite having audiograms within the normal range.