Hearing declines from 40–69 years of age.

<p>(A) UK Biobank: Mean DTT speech reception threshold (SRT; better ear) data, corrected for differences in socio-economic between samples. Exponential functions with an additive constant are fitted to the data. (B) National Study of Hearing (UK <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107720#pone.0107720-Davis1" target="_blank">[14]</a>): Mean pure tone average (PTA) thresholds (0.5, 1, 2, 4 kHz; better ear). (C) National Health and Nutrition Examination Survey (NHANES, US <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107720#pone.0107720-Hoffman1" target="_blank">[16]</a>): Mean PTA thresholds (0.5–4 kHz). Other data points from NIH Toolbox (US, 2011 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107720#pone.0107720-Gershon1" target="_blank">[18]</a>), Beaver Dam Epidemiology of Hearing Loss Study (US, 1993 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107720#pone.0107720-Cruickshanks1" target="_blank">[15]</a>), Blue Mountains Hearing Study (Australia, 1997–2000 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107720#pone.0107720-Chia1" target="_blank">[17]</a>).