Decline of speech understanding and auditory thresholds in the elderly
… audiometric decline is dominated by the threshold increases at 4 kHz (7.67 dB, SD 9.23 dB, or 14.61 dB/decade) and 8 kHz (5.97 db, SD 9.09 dB, or 11.32 dB/decade)
Maybe the Audacity equalizer should come with preset curves for “Grey-haired” and “White-haired” individuals 
Context, e.g. “we’re going sailing on his yacht” makes sense, “we’re going failing on his yacht” doesn’t.