Aging and decision criteria for the detection of tones in noise.

The performance of young (18--22 years) and old adults (55--64 years) on an auditory task was compared using signal detection procedures. Subjects used a confidence rating scale to report the presence or absence of a 6000 Hz pure tone embedded in Gaussian noise. The tone was set at eigher 35, 50, or 65 dB SPL. Younger subjects showed perfect sensitivity at all dB levels, and the sensitivity of older subjects increased as a function of the dB level. Discrimination was then tested at 20 and 30 dB in another sample of younger subjects. We found that this group tended to respond much less conservatively than the older group, even though the task was of comparable difficulty.