Biomedical subjects

Stephan Getzmann

Publications and source records attributed to Stephan Getzmann.

10 recordsLinked to original sources

PubMed2006

Saltation in pitch perception.

Sensory saltation is a spatiotemporal illusion in which the location of a brief stimulus is displaced towards a subsequent one following closely in time and space. This study investigated in three experiments whether or not saltation is present in spectral pitch, a non-spatial dimension. Employing the "symmetrical-rabbit" paradigm, listeners judged the continuity of sequences of six short tones, differing in pitch (Exp. 1). Furthermore, the "reduced-rabbit" paradigm consisting of only three short tones was used in combination with an objective two-alternative forced-choice task (Exp. 2) and a subjective judgment task (Exp. 3). All findings indicated displacements in pitch towards subsequent tones when the interstimulus interval between the tones was short, and the frequency separation was small. This suggests a saltation-like illusion for non-spatial stimulus parameters. Possible explanations are discussed in view of the supramodal characteristic of the phenomenon.

Acoustic Stimulation↗

PubMed2006

Horizontal and vertical effects of eye-position on sound localization.

The effect of gaze direction on the localization of sound sources was investigated in the azimuthal and elevational dimension using a pointing task. In both dimensions, eccentric eye-position induced a significant shift in sound localization that was opposite to the direction of eccentricity. This finding is in accordance with the view that the azimuthal and elevational components of the auditory spatial information are processed in common neural substrates.

Acoustic Stimulation↗

PubMed2005

Shifting the onset of a moving sound source: a Fröhlich effect in spatial hearing.

When observers are presented with a visual target in motion, they typically remember its onset position to be displaced in the direction of motion. The present study investigated a similar effect in the auditory modality. In a dark anechoic environment, an auditory target (short noise pulses) appeared randomly at a peripheral or a central azimuthal position and moved from left to right or from right to left along the frontal horizontal plane. Relative judgments were made to determine the onset position of motion: Employing a two-alternative forced-choice task, listeners compared the onset position of the target to a 2-s visual reference stimulus presented at the left or right of the auditory onset position. In comparison with stationary targets, the onset positions of moving targets were localized as displaced in the direction of motion. The most prominent displacement occurred when the visual reference stimulus was presented after the auditory motion. With the reference stimulus presented before the auditory motion, the displacement was significantly reduced. Moreover, the displacement was stronger with peripheral than with central onset positions. These findings suggest the existence of a potential analogue of the Fröhlich effect in the auditory modality. An auditory spatial attention mechanism is proposed that may have given rise to the observed pattern of results.

Acoustic Stimulation↗

PubMed2005

Representational momentum in spatial hearing does not depend on eye movements.

The perceived final position of a moving object usually seems to be displaced in the direction of motion. This displacement effect, termed representational momentum, has been reported for both visual and acoustic targets. This study investigated whether representational momentum in the auditory modality depends on oculomotor behavior during target presentation. In a dark anechoic environment, subjects localized the final position of a horizontally moving acoustic target (continuous noise) by using a hand pointer. Subjects were instructed to pursue the acoustic target with their eyes, to maintain central gaze direction, or to fixate a central visual fixation point. Forward displacements of the perceived final target position occurred irrespective of the eye-movement condition. This result is not consistent with previous findings in the visual modality indicating a reduction of forward displacement for continuously moving targets with fixation. It is suggested that factors other than oculomotor behavior are the source of representational momentum in spatial hearing.

Acoustic Stimulation↗

PubMed2004

Spatial discrimination of sound sources in the horizontal plane following an adapter sound.

The effect of a preceding (adapter) sound on the spatial discrimination of two subsequent, successively presented (target) sounds was tested in the horizontal plane. The adapter and the first target were located in front of the subject or 30 degrees to the right of the midline; both sounds were presented either at the same location or at different locations. The second target was located to the right or the left of the first. Sound spectra of the 3-s adapter and the 100-ms targets were either high (4.5-18 kHz) or low (1-4 kHz) in frequency. Fifteen subjects judged the position of the second target relative to the first in a two-alternative forced-choice paradigm. In comparison with a no-adapter control condition, in which no sound preceded, discrimination performance was increased when adapter and first target were presented at the same location and when both sounds consisted of the same frequency spectrum. No improvement occurred when adapter and targets differed in location or frequency. The results are consistent with previous results on post-adaptation discrimination of interaural time differences. Possibly, spatial adaptation of the underlying mechanisms of auditory localization may explain the discrimination aftereffect.

Acoustic Stimulation↗

PubMed2004

Fast reducers, slow augmenters: a psychophysiological analysis of temperament-related differences in reaction time.

Augmenting-reducing theory describes temperament-related differences in the modulation of stimulation. Reducers are supposed to need more stimulation than augmenters because of a cortical attenuation of incoming stimuli. The study investigated differences between augmenters and reducers (classified by questionnaire) in performance and information processing strategies in a simple reaction time task. Fifty-two subjects (27 augmenters, 25 reducers) took part in a visual reaction time task with go- and catch-trials (30%). Reaction times, commission errors, and psychophysiological indicators of information processing (N1, P300, EMG) were recorded. Reducers were faster and exhibited more commission errors than augmenters. Moreover, reducers exhibited higher N1-amplitudes, faster EMG-onsets and higher EMG-amplitudes than augmenters. An additional pain tolerance test revealed that male reducers were more pain tolerant than the other participants. These results are consistent with the proposition that reducers have a higher need for stimulation than augmenters. Probably, they utilize locomotor activity in order to compensate for their attenuated arousal.

Adult↗

PubMed2004

Representational momentum in spatial hearing.

The final position of a moving visual object usually appears to be displaced in the direction of motion. We investigated this phenomenon, termed representational momentum, in the auditory modality. In a dark anechoic environment, an acoustic target (continuous noise or noise pulses) moved from left to right or from right to left along the frontal horizontal plane. Listeners judged the final position of the target using a hand pointer. Target velocity was 8 degrees s(-1) or 16 degrees s(-1). Generally, the final target positions were localised as displaced in the direction of motion. With presentation of continuous noise, target velocity had a strong influence on mean displacement: displacements were stronger with lower velocity. No influence of sound velocity on displacement was found with motion of pulsed noise. Although these findings suggest that the underlying mechanisms may be different in the auditory and visual modality, the occurrence of displacements indicates that representational-momentum-like effects are not restricted to the visual modality, but may reflect a general phenomenon with judgments of dynamic events.

Acoustic Stimulation↗

PubMed2003

A comparison of the contrast effects in sound localization in the horizontal and vertical planes.

The effect of a background sound on the auditory localization of a single sound source was examined. Nine loudspeakers were arranged crosswise in the horizontal and the median vertical plane. They ranged from -20 degrees to +20 degrees, with the center loudspeaker at 0 degree azimuth and elevation. Using vertical and horizontal centimeter scales, listeners verbally estimated the position of a 500-ms broadband noise stimulus being presented at the same time as a 2 s background sound, emitted by one of the four outer loudspeakers. When the background sound consisted of continuous broadband noise, listeners consistently shifted the apparent target positions away from the background sound locations. This auditory contrast effect, which is consistent with earlier findings, equally occurred in both planes. But when the background sound was changed to a pulse train of noise bursts, the contrast effect decreased in the horizontal plane and increased in the vertical plane. This discrepancy might be due to general differences in the processing of interaural and spectral localization information.

Adult↗

PubMed2003

The influence of the acoustic context on vertical sound localization in the median plane.

The influence of background sounds (frames) on vertical localization of single sound sources (targets) was examined in four experiments. Loudspeakers (five targets and four frames) were positioned in the median plane, ranging from +30 degrees to -30 degrees above and below the subject's ear level. The subjects determined the vertical position of the targets by either verbal judgments or manual pointing. Frame and target sounds were presented concurrently or successively with a 1-sec interval; both consisted of (1) 300-Hz square waves, (2) noise, or (3) targets of noise and frames of 300-Hz square waves. Particularly in the second condition, the subjects consistently shifted the apparent target positions away from the frame locations. This contrast effect persisted even 1 sec after the offset of the frames. No effect was found with different waveforms for the frame and the target. Results are related to recent findings indicating a similar effect in the azimuthal dimension. Possibly the effect is based on a mechanism in which the auditory system adapts to recently heard sound source positions.

Acoustic Stimulation↗

PubMed2002

The effect of eye position and background noise on vertical sound localization.

The influence of the eye position in combination with a simultaneously presented background (frame) sound on the auditory localization of a single (target) sound source was investigated in the median vertical plane (MVP). Five loudspeakers ranged from -20 degrees to +20 degrees with the center speaker at 0 degrees elevation. Listeners verbally estimated the position of a 500-ms noise stimulus, which was presented while they were fixating visual targets in various elevations. The perceived sound elevation appeared to be shifted 8.6 degrees on average towards the direction of eccentric gaze. When the target was temporarily embedded in a 2-s frame sound (emitted by one of the two outer loudspeakers) and the gaze was fixated at a straight-ahead position, the listeners consistently shifted the apparent target positions about 4 degrees away from the frame locations. This auditory contrast effect, which is consistent with earlier findings, remained even if the gaze direction deviated from straight ahead. It is concluded that the auditory contrast effect exists independently from the eye position effect and that the two effects act separately on auditory sound localization.

Acoustic Stimulation↗