Age effects on duration discrimination with simple and complex stimuli.

This study examined age-related changes in temporal processing by measuring DLs for signal duration using simple and complex stimuli. Previous research has shown that elderly listeners exhibit difficulty discriminating duration changes in simple sounds, suggesting the possibility of age-related changes in central timing mechanisms. The present experiments examined the interactive effects of aging, hearing loss, and stimulus complexity on duration discrimination. Four groups participated: young and elderly listeners with normal hearing, and young and elderly listeners with hearing loss. Duration DLs were measured for 250-ms tone bursts and for silent gaps between tone bursts that were presented either in isolation or embedded as target stimuli within tonal sequences. The tone sequences were composed of five sequential 250-ms components. Stimulus complexity was varied by changing the sequential order of tone frequencies and the location of an embedded target component across listening conditions. Analyses of results revealed the following: Elderly listeners performed more poorly than younger listeners in nearly all stimulus conditions, the effects of stimulus complexity on discrimination were greatest among elderly listeners, and hearing loss had no systematic effect on discrimination performance.