Development of an underwater binaural head model

Abstract

The human auditory system has difficulty localizing sound in aquatic environments, where the acoustical properties of water greatly impede normal methods of binaural localization. Apparent interaural time differences are smaller in water than in air for sound sources at a given azimuth. In water, the head is no longer approximately rigid. In the current study, a new computational model, capable of predicting interaural time and level differences (ITDs and ILDs, respectively) for sounds encountering a non-rigid sphere in diverse environments, is used. For experimental validation, a hollow steel sphere with antipodal hydrophones for ears is exposed to noise bursts in an underwater environment. The sphere can be filled with various materials to alter the apparatus' rigid qualities. ITDs and ILDs will be calculated from recordings of these noises and compared to a theoretical model for sound propagation around rigid and non-rigid heads in an effort to better characterize binaural hearing in underwater surroundings. Both the model and the experiment will be introduced in this presentation. The findings have significant implications for the future development of reliable methods for improving sound localization in underwater environments, for instance for recreational divers.