Assessing the contribution of binaural cues for apparent source width perception via a functional model

In echoic conditions, sound sources are not perceived as point sources but appear to be expanded. The expansion in the horizontal dimension is referred to as apparent source width (ASW). To elicit this perception, the auditory system has access to fluctuations of binaural cues, the interaural time differences (ITDs), interaural level differences (ILDs) and the interaural coherence (IC).

To quantify their contribution to ASW, a functional model of ASW perception was exploited using the TWO!EARS auditory-front-end (AFE) toolbox. The model determines the leftand right-most boundary of a sound source using a statistical representation of ITDs and ILDs based on percentiles integrated over time and frequency.

The model’s performance was evaluated against psychoacoustic data obtained with noise, speech and music signals in loudspeakerbased experiments. A robust model prediction of ASW was achieved using a cross-correlation based estimation with either IC or ITDs, in contrast to a combination of ITDs and ILDs where the performance slightly decreased.