Jane F. MacNeil
Dept. of Psychol., Univ. of Calgary, 2500 University Dr., N. W., Calgary, AB T2N 1N4, Canada
This study investigated the perceptual abilities of young (18--28 years) and elderly (65--75 years) adults to discriminate suprathreshold short duration dynamic frequency transitions. Influences of frequency region (1 to 3 kHz), transition direction (upward or downward gliding), offset frequencies (converging or diverging), and background condition (quiet or noise) were examined. Signals were 60-ms transitions classified according to whether or not: they diverged to differing offset frequencies, converged on a common terminal frequency; and had an upward or downward trajectory. Young adults displayed smaller just-noticeable differences (jnds) relative to the elderly, and the elderly showed greater effects for frequency region, noise, and transition direction. Signals centered at 3 kHz were considerably more difficult for the elderly to distinguish even though hearing sensitivity levels were comparable across both groups at this region. However, among both age groups diverging signals produced smaller jnds than did converging signals. The results of the study showed that elderly subjects with comparable audiological profiles to young adults, or a mild sensorineural hearing loss, have greater difficulty distinguishing dynamic sounds, especially in background noise.