Objectives: The effects of directing, switching, and misdirecting auditory spatial attention in a complex listening situation were investigated in 8 younger and 8 older listeners with normal-hearing sensitivity below 4 kHz.
Design: In two companion experiments, a target sentence was presented from one spatial location and two competing sentences were presented simultaneously, one from each of two different locations. Pretrial, listeners were informed of the call-sign cue that identified which of the three sentences was the target and of the probability of the target sentence being presented from each of the three possible locations. Four different probability conditions varied in the likelihood of the target being presented at the left, center, and right locations. In Experiment 1, four timing conditions were tested: the original (unedited) sentences (which contained about 300 msec of filler speech between the call-sign cue and the onset of the target words), or modified (edited) sentences with silent pauses of 0, 150, or 300 msec replacing the filler speech. In Experiment 2, when the cued sentence was presented from an unlikely (side) listening location, for half of the trials the listener’s task was to report target words from the cued sentence (cue condition); for the remaining trials, the listener’s task was to report target words from the sentence presented from the opposite, unlikely (side) listening location (anticue condition).
Results: In Experiment 1, for targets presented from the likely (center) location, word identification was better for the unedited than for modified sentences. For targets presented from unlikely (side) locations, word identification was better when there was more time between the call-sign cue and target words. All listeners benefited similarly from the availability of more compared with less time and the presentation of continuous compared with interrupted speech. In Experiment 2, the key finding was that age-related performance deficits were observed in conditions requiring anticue but not cue responses.
Conclusions: The findings from Experiment 1 suggest that for both age groups, stream continuity mediates the process of allocating and maintaining auditory spatial attention when the target originates at an expected location, but that time is needed for the reallocation of auditory spatial attention when the target originates at an unexpected location. The findings from Experiment 2 suggest that when attention is momentarily misdirected, difficulties disengaging attention may help explain why older adults with good hearing report difficulty communicating in multi-talker listening situations.
The effects of directing, switching, and misdirecting auditory spatial attention in a multi-talker listening situation were investigated in 8 younger and 8 older listeners with good hearing. In two experiments, a target sentence was presented from one location and two competing sentences were presented simultaneously, one from each of two different locations. In experiment 1, all listeners benefited similarly from having more compared with less time to switch attention one location to another. In experiment 2, age-related deficits were observed in conditions where rapid disengaging of attention was required, suggesting that older adults experience difficulty when attention is momentarily misdirected.
1Phonak Canada Ltd, Mississauga, Ontario, Canada; 2Department of Speech-Language Pathology, University of Toronto, Toronto, Ontario, Canada; 3Toronto Rehabilitation Institute, Toronto, Ontario, Canada; and 4Department of Psychology, University of Toronto Mississauga, Mississauga, Ontario, Canada.
ACKNOWLEDGMENTS: The authors thank Robert Quelch for his assistance with data collection, Huiwen Goy for her assistance in editing the stimuli, James Qi for programming and technical support, and the participants for their valuable contributions.
This research was made possible by support from the Canadian Institutes of Health Research (MOP-15359) and the Natural Sciences and Engineering Research Council of Canada (RGPIN 138472-05).
Portions of this article were presented at the annual meeting of the American Auditory Society in Scottsdale, Arizona, in May 2010, the Cognitive Aging Conference in Atlanta, Georgia in April, 2010, and at the 159th meeting of the Acoustical Society of America in Baltimore, Maryland, in April 2010.
The authors declare no conflict of interest.
Address for correspondence: Gurjit Singh, Department of Speech-Language Pathology, Rehabilitation Sciences Building, Faculty of Medicine, University of Toronto, 160-500 University Avenue, Toronto, Ontario, Canada, M5G 1V7. E-mail: firstname.lastname@example.org