Neuronal Representations of Multiple Concurrent Sound Sources

We are regularly exposed to several concurrent sounds, producing a mixture of binaural cues. The neuronal mechanisms underlying the localization of concurrent sounds are, however, not well understood. The major binaural cues for localizing low-frequency sounds in the horizontal plane are interaural time differences (ITDs). Auditory brainstem neurons encode ITDs by firing maximally in response to “favorable” ITDs and weakly or not at all in response to “unfavorable” ITDs. Our recent findings indicate that the spectral composition of a concurrent sound strongly influences the spatial processing of ITD-sensitive DNLL neurons. In this project we intend to work out a theory to explain how the ITD of a stimulus is neuronally represented such that this representation is invariant against its frequency composition and  the changes in induced by concurrent sound stimuli.