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Processing of harmonic stimuli in auditory scene analysis - studies in model systems

Georg M. Klump, Naoya Itatani, and Astrid Klinge

Animal Physiology and Behaviour Group, Institute for Biology and Environmental Sciences, Carl-von-Ossietzky University Oldenburg, Germany


Many natural signals are composed of multiple harmonic frequency components. The auditory system integrates the components of such signals into perceptual objects that are processed in auditory scene analysis separate from other sounds. If a frequency component deviates from the harmonic frequency representative for the complex, this mistuning can be detected and being sufficiently large the mistuning leads to the perceptual segregation of the mistuned tone from the harmonic complex into two auditory objects in the scene. Human and animal psychophysical studies that are summarized in the workshop presentation have explored the cues involved in the perceptual grouping of frequency components in complex tones. Besides the mistuning of partials, other cues that have been identified to affect the integration of components into the harmonic complex are common onset and spatial location cues. The physiological mechanisms underlying the integration of frequency components in the representation of complex tones a less well studied than the psychophysics. The presentation will summarize results from studies in animal models that indicate a strong role of temporal processing in the representation of complex tones and mistuning perception. The role of different cues in determining the neuronal response patterns evoked by complex tones with and without mistuned components can be predicted by modeling the representation of such sounds in the auditory periphery and predicting the evoked auditory-nerve response patterns on which the central auditory system must rely in the analysis.