We will present work on a systems identification approach to understanding binaural circuits for sound localization in the horizontal plane.

"Cochlear disparities and the internal-delay puzzle." (Mark Sayles, Bertrand Fontaine, Philip H. Smith, Philip X. Joris) 

The classic ("Jeffress") model for inter-aural time sensitivity posits a set of opposing neural delay lines in the auditory brainstem to account for the presence of an internal time delay in the circuit processing binaural cues. There is very little anatomical evidence to support this view. Our recent data suggests a more elegant solution: the time delays arise due to systematic differences in cochlear tuning between the two ears' inputs to binaural neurons. This provides the precise set of time and phase delays required to account for major phenomena in binaural hearing.