PROGRAMM - DAGA 2012

Programm DAGA 2012 103Sitzung „Psychoakustik 1“Di. 14:00 aurum 2.07 Psychoakustik 1A computational model of auditory stream segregation based on atemporal coherence analysisT. Dau, S. Christiansen und M. JepsenTechnical University of DenmarkThe ability to perceptually separate acoustic sources and to focus one’sattention on a single source at a time is essential for our communication.In this study, a physiologically inspired model of human auditory processing(Jepsen et al., 2008) was used as a front end of a model for auditorystream segregation. A temporal coherence analysis (Elhilali et al., 2009)was applied at the output of the preprocessing, using the coherenceacross tonotopic channels to group activity across frequency. Using thisapproach, the described model is able to quantitatively account for classicalstreaming phenomena relying on frequency separation and tonepresentation rate, such as the temporal coherence boundary and thefission boundary (van Noorden, 1975). The same model also accountsfor the perceptual grouping of distant spectral components in the case ofsynchronous presentation. The most essential components of the frontendand back-end processing in the framework of the presented modelare analyzed and future perspectives discussed.Di. 14:25 aurum 2.07 Psychoakustik 1Differential contribution of interaural time and level differences tothe precedence effect at high frequenciesB.U. SeeberMRC Institute of Hearing Research (UK)The precedence effect (PE) allows us to locate sound sources correctlyin rooms despite the presence of interfering reflections. It was shown tofunction at high frequencies with highly modulated stimuli. These studieswere done in the free-field where interaural time (ITDs) and level(ILDs) differences are in their natural combination. The present studyinvestigated the relative contribution of ILDs and ITDs to the PE withhigh-frequency zero-phase harmonic complex tones. A localization dominancetask was used where participants indicated the location of thelead-lag stimuli and rated if sounds were perceived as fused. Preliminaryresults showed that the PE exists with either ITDs or ILDs applied tolead and lag while the other binaural cue was held at zero. Patterns forlocalization dominance and fusion were nearly identical for ITD and ILDconditions. Fusion of lead and lag extended to longer delays with smallercue magnitudes, i.e. the more binaural cues differed between leadand lag the stronger was the tendency for their segregation. The resultssupport the idea that the PE shares the same mechanism for ITDs andILDs.