A closer look at the representation of interaural differences in a binaural model

In this contribution, we investigate the internal representations given by the binaural model proposed by Breebaart et al. [1]. We focus on the cues used by an arti??cial observer when determining just noticeable differences in interaural time differences (ITDs) or interaural level differences (ILDs). The binaural processor consists of an array of excitation-inhibition (EI) cells, each characterized by its internal interaural delay and internal interaural attenuation. This model is conceptually similar to a cross-correlation model and the relevant properties for ITD and ILD discrimination tasks are changes in the binaural pattern along the internal delay and the internal attenuation axis. For ITD discrimination of two coherent signals, the traditional approaches consist of searching for a displacement of the peak of the normalized cross-correlation function or measuring the difference in the cross-correlation function at lag zero. These approaches will be compared to our strategy which maximizes the differences between the two normalized cross-correlation functions. Threshold predictions depend on which position along the internal delay line is analyzed. The characteristics of the binaural pattern with regard to ILD discrimination tasks will also be investigated and compared to those that are relevant for ITD discrimination.