Fri, 04/12/2013 - 1:15pm - 2:30pm
Seminar Room, The Knoll
Behavioral and Electrophysiological Evidence for Impaired Central Auditory Space Processing in Older Adults
University of Leipzig
Aging is associated with a decline in hearing sensitivity as well as substantial changes in the perception of auditory objects – though both phenomena must not occur jointly. Most prominently, older adults show difficulties in understanding speech in challenging acoustic environments. As a part of speech perception, location of sound sources have to be processed in order to assign auditory objects (i.e. speakers) to distinct spatial positions and also to differentiate multiple sound sources (for instance, multiple speakers and transient background sounds). There is evidence that localization performance is impaired in older adults. However, there is need to comparatively analyze localization accuracy and acuity in older adults to understand the relation of encoding isolated sound sources compared to the situation where neighboring sound sources have to be differentiated. To date, we lack knowledge about what specific processing mechanism is responsible for the decline in localization performance in older adults.
Behavioral data on localization accuracy and acuity (measured as Minimum Audible Angle [MAA]) measured in the acoustic free-field will be presented and discussed in terms of impaired processing of binaural cues and a modified representation of sound sources at the auditory cortex as a consequence of impaired temporal processing. Further, this hypothesis will be strengthened by relating behavioral data to electrophysiological recordings of the pre-attentive change detection component - Mismatch Negativity. It will be emphasized that the central auditory processing of space is declined in older adults. However, there is a trade-off between behavioral and electrophysiological measures, which highlights the importance of an efficiently working attention system that can compensate for the impairment at the central auditory processing levels by top-down control. It will be concluded that age-related decline in central auditory space processing in part contributes to the speech comprehension problems in challenging acoustic environments.