Age-related differences in discrimination of temporal intervals in accented tone sequences

Abstract

The study measured listener sensitivity to increments of a target inter-onset interval (IOI) embedded within isochronous tone sequences that featured a single accented tonal component. The sequences consisted of six 1000-Hz tone bursts separated by silent intervals to establish equal tonal IOIs of 200 ms within the sequence. Tone burst durations within the sequences were 50 ms, except one tone had a longer duration of 100 ms to produce a perception of accent. Duration DLs in ms for increments of a single sequence IOI were measured adaptively by adjusting the duration of the silent interval between two tones. Sequence position of the target IOI differed across conditions. Listeners included young normal-hearing adults and older adults with and without hearing loss. Discrimination performance of the two older listener groups was equivalent and significantly poorer than that of the younger listeners in each discrimination condition. The age-related discrimination deficits were independent of sequence locations of both the target interval and the accented tonal component. Comparative DLs collected for target intervals in unaccented tone sequences with equal tone durations revealed that the detrimental effects of accent on temporal discrimination were primarily restricted to the older listeners.

Copyright 2009 Elsevier B.V. All rights reserved.

Figures

Fig. 1

Schematic diagram of stimulus conditions. Panel a shows unaccented (top row) and single accented tones in different sequence locations (rows 2 through 4); Panel b shows an accented sequence with the three possible target IOI positions.

Fig. 2

Mean relative IOI DLs in percent as a function of target interval position for each listener group, shown separately in each panel for each sequence accent condition. Error bars represent one standard error of the mean.

Fig. 3

Mean relative IOI DLs of the three listener groups in each sequence accent condition (collapsed across target interval position). Error bars represent one standard errors of the mean.

Fig. 4

Mean relative IOI DLs in percent in the three target interval positions shown for each accent condition (data collapsed across listener group). Error bars represent one standard error of the mean.

Fig. 5

Mean relative IOI DLs in percent as a function of target interval position of the younger and older listeners (normal and hearing-impaired groups combined) in the unaccented and accented sequence conditions (collapsed across accent conditions). Error bars represent one standard error of the mean.