Static and dynamic cocktail party listening in younger and older adults

Verbal communication often takes place in situations with several simultaneous speakers ("cocktail party listening"). These situations can be static (only one listening target) or dynamic (with alternating targets). In particular, dynamic cocktail party listening is believed to generate extra cognitive load and appears to be particularly demanding for older listeners. Two groups of younger and older listeners with good hearing and normal cognition participated in the present study. Three different, spatially separated talker voices uttering matrix sentences were presented to each listener with varying types and probabilities of target switches. Moreover, several neuropsychological tests were conducted to investigate general cognitive characteristics that may be important for speech understanding in these situations. In a static condition with a priori knowledge of the target talker, both age groups revealed very high speech recognition performance. In comparison, dynamic conditions caused extra costs associated with the need to monitor different potential sound sources and to refocus attention when the target changed. The amount of costs depended on the probability and type of target talker alterations. Again, no significant age-group differences were found. No significant associations of cognitive characteristics and costs could be shown. However, a more fine-grained analysis based on the calculation of general and specific switch costs showed different mechanisms in older and younger listeners. This study confirms that dynamic cocktail party listening is associated with costs that depend on the type and probability of target switches. It extends previous research by showing that the effects of switching type and probability are similar for younger and older listeners with good hearing and good cognitive abilities. It further shows that, despite comparable costs of dynamic listening, mechanisms are different for the two age groups, as switching auditory attention may be preserved with aging, but monitoring different sound sources appears to be more difficult for older adults.