Examining auditory selective attention. From dichotic towards realistic environments

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Abstract

The aim of the present thesis is to examine the cognitive control mechanisms underlying auditory selective attention by considering the inĆuence of variables that increase the complexity of an auditory scene.Therefore, technical aspects such as dynamic binaural hearing, room acoustics and head movements as well as those that inĆuence the efficiency of cognitive processing are taken into account. Step-by-step the well-established dichotic-listening paradigm is extended into a ŞrealisticŤ spatial listening paradigm.Conducted empirical surveys are based on a paradigm examining the intentional switching of auditory selective attention.Spoken phrases are simultaneously presented by two speakers to participants from two of eight azimuthal positions.The stimuli are phrases that consist of a single digit (1 to 9, excluding 5), in some experiments followed by either the German direction ŞUPŤ or ŞDOWNŤ.A visual cue indicates the targetŠs spatial position, prior to auditory stimulus onset.Afterwards, participants are asked to identify whether the target number is arithmetically smaller or greater than Ąve and to categorize the direction.Human performance measure differences in reaction times and error rates between the repetition of the targetŠs spatial position and the related switch (i.e.switch costs) describe the loss of efficiency associated with redirecting attention from one targetŠs location to another.To examine whether the irrelevant auditory information is decoded, interference in the processing of task-relevant and taskirrelevant information is created in the paradigm.Using the binaural-listening paradigm, the ability to intentionally switch auditory selective attention is tested when applying different methods of spatial reproduction.Essential differences between real sources, an individual and a nonindividual binaural synthesis reproduced with headphones as well as a binaural synthesis based on Cross-Talk Cancellation are found.This indicates how the loss of individual information reduces the ability to inhibit irrelevant information.As a step towards multi-talker scenarios in realistic environments participants are tested in differently reverberating environments.Switch costs are highly affected by reverberation and the inhibition is also impaired by to be unattended information.Age-related effects are also found when applying the binaural-listening paradigm, indicating difficulties for elderly to suppress processing the distractorŠs speech.

Authors 1

1. Josefa Oberem corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   aus Bonn , Deutschland

   Fakultät für Elektrotechnik und Informationstechnik der

   Rheinischen-Westfälischen Technischen Hochschule Aachen

   Univ

   aus Bonn, Deutschland

   zur Erlangung des akademischen Grades einer