Development of an underwater binaural head model

Abstract

The human brain has difficulty localizing sound in aquatic environments, where the acoustical properties of water greatly impede the mechanisms by which the brain interprets binaural signals. In this experiment, a hollow steel sphere with antipodal hydrophones is exposed to noise bursts in an underwater environment. The sphere can be filled with various materials to alter the apparatus’ rigid qualities. Interaural time and level differences (ITDs and ILDs, respectively) are calculated from recordings of these noises and compared to a theoretical model for sound propagation around a non-rigid head in an effort to better characterize binaural hearing in underwater surroundings. While the theoretical behavior of sound diffracting around a rigid head has been well documented, the similar problem involving a flexible head has largely been left to experimental methods due to the computational complexity of the task. In the current study, a new computational model, capable of predicting ITDs and ILDs for sounds encountering a non-rigid sphere in diverse environments, is used. 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.