Josefa Oberem

Intentional attention switching in dichotic listening: Exploring the efficiency of nonspatial and spatial selection

Using an auditory variant of task switching, we examined the ability to intentionally switch attention in a dichotic-listening task. In our study, participants responded selectively to one of two simultaneously presented auditory number words (spoken by a female and a male, one for each ear) by categorizing its numerical magnitude. The mapping of gender (female vs. male) and ear (left vs. right) was unpredictable. The to-be-attended feature for gender or ear, respectively, was indicated by a visual selection cue prior to auditory stimulus onset. In Experiment 1, explicitly cued switches of the relevant feature dimension (e.g., from gender to ear) and switches of the relevant feature within a dimension (e.g., from male to female) occurred in an unpredictable manner. We found large performance costs when the relevant feature switched, but switches of the relevant feature dimension incurred only small additional costs. The feature-switch costs were larger in ear-relevant than in gender-relevant trials. In Experiment 2, we replicated these findings using a simplified design (i.e., only within-dimension switches with blocked dimensions). In Experiment 3, we examined preparation effects by manipulating the cueing interval and found a preparation benefit only when ear was cued. Together, our data suggest that the large part of attentional switch costs arises from reconfiguration at the level of relevant auditory features (e.g., left vs. right) rather than feature dimensions (ear vs. gender). Additionally, our findings suggest that ear-based target selection benefits more from preparation time (i.e., time to direct attention to one ear) than gender-based target selection.

Intentional switching in auditory selective attention: Exploring age-related effects in a spatial setup requiring speech perception

Using a binaural-listening paradigm, age-related differences in the ability to intentionally switch auditory selective attention between two speakers, defined by their spatial location, were examined. Therefore 40 normal-hearing participants (20 young, Ø 24.8years; 20 older Ø 67.8years) were tested. The spatial reproduction of stimuli was provided by headphones using head-related-transfer-functions of an artificial head. Spoken number words of two speakers were presented simultaneously to participants from two out of eight locations on the horizontal plane. Guided by a visual cue indicating the spatial location of the target speaker, the participants were asked to categorize the targets number word into smaller vs. greater than five while ignoring the distractors speech. Results showed significantly higher reaction times and error rates for older participants. The relative influence of the spatial switch of the target-speaker (switch or repetition of speakers direction in space) was identical across age groups. Congruency effects (stimuli spoken by target and distractor may evoke the same answer or different answers) were increased for older participants and depend on the targets position. Results suggest that the ability to intentionally switch auditory attention to a new cued location was unimpaired whereas it was generally harder for older participants to suppress processing the distractors speech.

Intentional Preparation of Auditory Attention-Switches: Explicit Cueing and Sequential Switch-Predictability

In an auditory attention-switching paradigm, participants heard two simultaneously spoken number-words, each presented to one ear, and decided whether the target number was smaller or larger than 5 by pressing a left or right key. An instructional cue in each trial indicated which feature had to be used to identify the target number (e.g., female voice). Auditory attention-switch costs were found when this feature changed compared to when it repeated in two consecutive trials. Earlier studies employing this paradigm showed mixed results when they examined whether such cued auditory attention-switches can be prepared actively during the cue–stimulus interval. This study systematically assessed which preconditions are necessary for the advance preparation of auditory attention-switches. Three experiments were conducted that controlled for cue-repetition benefits, modality switches between cue and stimuli, as well as for predictability of the switch-sequence. Only in the third experiment, in which predictability for an attention-switch was maximal due to a pre-instructed switch-sequence and predictable stimulus onsets, active switch-specific preparation was found. These results suggest that the cognitive system can prepare auditory attention-switches, and this preparation seems to be triggered primarily by the memorised switching-sequence and valid expectations about the time of target onset.

Examining auditory selective attention in realistic, natural environments with an optimized paradigm

The topic of the collaborative project is the exploration of cognitive control mechanisms underlying auditory selective attention. The aim is to examine the influence of variables that increase the complexity of the auditory scene with respect to technical aspects (dynamic binaural hearing with consideration of room acoustics and head movements) and that influence the efficiency of cognitive processing. Using a binaural-listening paradigm, the ability to intentionally shift auditory attention in various anechoic setups was tested. An anechoic reproduction fails to represent realistic listening experiences. The original paradigm is extended to use longer stimuli to offer more opportunities. Spoken phrases by two speakers were presented simultaneously to subjects from two of eight positions. The stimuli were phrases that consisted of a single number word followed by either the German direction “UP” or “DOWN”. Guided by a visual cue prior to auditory stimulus onset, subjects were asked to identify whether th...

Experiments on authenticity and naturalness of binaural reproduction via headphones

Binaural stimuli presented via headphones need to be plausible in localization and sound coloration for a successful reproduction of an acoustic scene, especially for experiments on auditory selective attention. The goal is to provide artificially generated acoustic scenes in a way that the difference between a real situation and an artificially generated situation has no influence in psychoacoustic experiments. The quality and reliability of binaural reproduction via headphones comparing two different microphone setups (miniature microphone in open dome and ear plug) used for individualized Head-Related Transfer Functions and headphone transfer function measurements is analyzed. Listening tests are carried out focusing on authenticity, naturalness and distinguishability in a direct comparison of real sources and binaural reproduction via headphones. Results for three different stimuli (speech, music, pink noise) are discussed.

Performance of binaural technology for auditory selective attention

A room-acoustic situation with many sources is one of the best examples for auditory selective attention – relevant information should be selectively observed and irrelevant information should be ignored. In a joint research project between Acoustics and Psychology at RWTH Aachen University the intentional switching of auditory selective attention is examined using dichotic and binaural presentation of the stimuli. The goal is to provide artificially generated acoustic scenes (e.g. typical classroom situation, open plan offices etc.), as in psychoacoustic experiments on auditory selective attention no differences between a real situation and an artificially generated situation occur. Therefore at first we investigate various binaural reproduction and equalization methods using experiments in auditory selective attention. Headphones must always be adequately equalized if they are to deliver high perceptual plausibility. However, the transfer function between headphones and ear drums varies between differen...

Examining auditory selective attention in reverberant environments

Using a well-established binaural-listening paradigm, the ability to intentionally switch auditory selective attention was examined under anechoic, low reverberation (0.8 s) and high reverberation (1.75 s) conditions. Twenty-four young, normal-hearing subjects were tested in a within-subject design to analyze influences of the reverberation times. Spoken word pairs by two speakers were presented simultaneously to subjects from two of eight azimuth positions. The stimuli were word pairs that consisted of a single number word (i.e., 1 to 9) followed by either the German direction “UP” or “DOWN.” Guided by a visual cue prior to auditory stimulus onset indicating the position of the target speaker, subjects were asked to identify whether the target number was numerically smaller or greater than five and to categorize the direction of the second word. Switch costs (i.e., reaction time differences between a position switch of the target relative to a position repetition) were larger for the high reverberation c...

Intentional switching in auditory selective attention: Exploring attention shifts with different reverberation times

ABSTRACT Using a well‐established binaural‐listening paradigm the ability to intentionally switch auditory selective attention was examined under anechoic, low reverberation (0.8 s) and high reverberation (1.75 s) conditions. Twenty‐three young, normal‐hearing subjects were tested in a within‐subject design to analyze influences of the reverberation times. Spoken word pairs by two speakers were presented simultaneously to subjects from two of eight azimuth positions. The stimuli consisted of a single number word, (i.e., 1 to 9), followed by either the direction “UP” or “DOWN” in German. Guided by a visual cue prior to auditory stimulus onset indicating the position of the target speaker, subjects were asked to identify whether the target number was numerically smaller or greater than five and to categorize the direction of the second word. Switch costs, (i.e. reaction time differences between a position switch of the target relative to a position repetition), were larger under the high reverberation condition. Furthermore, the error rates were highly dependent on reverberant energy and reverberation interacted with the congruence effect, (i.e. stimuli spoken by target and distractor may evoke the same answer (congruent) or different answers (incongruent)), indicating larger congruence effects under higher reverberation times. HighlightsReverberation has a great effect on reaction times when maintaining attention to one direction.Additional reverberant energy has no impact on intentional switching attention to other speakers.The ability to ignore a distracting source is significantly influenced by reverberation.Localization cues have a relevant effect on performance in tasks of auditory selective attention.