Using auditory models to study masking due to anthropogenic sound.

Abstract

The mammalian auditory system is a highly evolved acoustic signal processing system that performs well even in highly reverberant and cluttered acoustic environments. In cetaceans, the auditory system is even more highly evolved than vision and is extremely important for navigation, foraging, and social communication. As humans inject more and more acoustic energies into the marine environment, these important acoustic functions may become compromised. Unfortunately little is known about the impact of anthropogenic sounds that could mask biologically significant signals. In this study a desktop simulation environment was used to study masking effects in a variety of conditions. The acoustic scenarios were created by mixing cetacean vocalizations recorded under relatively quiet conditions with scaled recordings of shipping noise. Biophysical computer models (http://earlab.bu.edu) based on physiological and behavioral experiments performed on humans were extrapolated to represent several different cetacean species. Model parameters for species of interest were estimated from behavioral audiograms and from other available data. These models were then used to predict how different types of biologically significant sounds are represented in neural firing patterns and how the neural representation degrades in the presence of anthropogenic noise.