Basis Function Approaches for Two Dimensional Cochlear Models

The human cochlea possesses the amazing ability of analyzing audio signals. The structures and mechanisms behind its characteristic response to sound stimuli has been an active area of research for decades. It has been demonstrated that mathematical cochlear modeling poses a promising alternative to discover the elusive activities in an in vivo cochlea. However, despite the successful application of numerical methods such as the Wentzel-Kramers-Brillouin (WKB) method, finite difference method (FDM) and finite element method (FEM), the critical effects of the choice of basis functions have not been studied exclusively for the numerical solutions of cochlea models. This work presents the numerical solution procedures to two types of cochlear models using the basis function collocation approach. Accuracies and effectiveness of basis functions are evaluated by comparing simulation results with past experiment and physiological data. The time-domain solutions in response to various audio inputs are also shown. The cochlear model demonstrates sound processing abilities which are qualitatively comparable to physiological data. It is hoped that the results in this work would help in laying the foundation for future cochlear model solutions and cochlea-based audio signal processor

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

otorhinolaryngology; neurosciences; hearin

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

​The International Symposium on Hearing is a prestigious, triennial gathering where world-class scientists present and discuss the most recent advances in the field of human and animal hearing research. The 2015 edition will particularly focus on integrative approaches linking physiological, psychophysical and cognitive aspects of normal and impaired hearing. Like previous editions, the proceedings will contain about 50 chapters ranging from basic to applied research, and of interest to neuroscientists, psychologists, audiologists, engineers, otolaryngologists, and artificial intelligence researchers.

Neural Models of Subcortical Auditory Processing

An important feature of the auditory system is its ability to distinguish many simultaneous sound sources. The primary goal of this work was to understand how a robust, preattentive analysis of the auditory scene is accomplished by the subcortical auditory system. Reasonably accurate modelling of the morphology and organisation of the relevant auditory nuclei, was seen as being of great importance. The formulation of plausible models and their subsequent simulation was found to be invaluable in elucidating biological processes and in highlighting areas of uncertainty. In the thesis, a review of important aspects of mammalian auditory processing is presented and used as a basis for the subsequent modelling work. For each aspect of auditory processing modelled, psychophysical results are described and existing models reviewed, before the models used here are described and simulated. Auditory processes which are modelled include the peripheral system, and the production of tonotopic maps of the spectral content of complex acoustic stimuli, and of modulation frequency or periodicity. A model of the formation of sequential associations between successive sounds is described, and the model is shown to be capable of emulating a wide range of psychophysical behaviour. The grouping of related spectral components and the development of pitch perception is also investigated. Finally a critical assessment of the work and ideas for future developments are presented. The principal contributions of this work are the further development of a model for pitch perception and the development of a novel architecture for the sequential association of those groups. In the process of developing these ideas, further insights into subcortical auditory processing were gained, and explanations for a number of puzzling psychophysical characteristics suggested.Royal Naval Engineering College, Manadon, Plymout