A first sound is output by a first transducer in an earcup located at a pinna. Respective second sound based on the output of the first audio sound is detecting by each of one or more microphones in the earcup located at the pinna. Based on the respective detected second sound, a non-linear transfer function is determined which characterizes how sound is transformed via the pinna. A signal indicative of one or more audio cues for spatializing third sound is generated based on the determined non-linear transfer function.