Index of content:
Volume 128, Issue 6, December 2010
- ADVANCED-DEGREE DISSERTATION ABSTRACTS
128(2010); http://dx.doi.org/10.1121/1.3506767View Description Hide Description
The processing of the auditory system allows the separation of complex acoustical scenes into so-called auditory objects. The goal of this thesis was to shed some light on the ability of the auditory system to use combined across-frequency and binaural cues for the analysis of complex auditory environments. The first and second part of the thesis addresses the investigation of the processing of combined across-frequency and binaural signal properties in normally hearing listeners using psychoacoustical techniques and signal processing strategies. The third part concentrates on the influence of cochlear processing on psychoacoustic effects using a physical nonlinear and active model of the cochlea. The results of this thesis point out that the auditory system is able to process comodulation across frequency and interaural phase differences independently and over a broad frequency range. Hence, improvements of masked thresholds can be used in an optimal manner. The ability of the developed cochlea model to account for psychoacoustical data provides the basis to separate peripheral contributions to psychoacoustical effects from neural contributions. Contact: Bastian.Epp@uni-oldenburg.de.
128(2010); http://dx.doi.org/10.1121/1.3544557View Description Hide Description
Advances in oceanmodeling have improved such that high-resolution ocean forecasts are becoming available. This facilitates predicted time series of acoustic propagation conditions in the ocean which can greatly improve the planning of acoustic experiments. Modeling of acoustic transmission loss provides variation of acoustic performance with time. It is, however, very time consuming to compute acoustic propagation for many potential source/receiver combinations on an area-wide grid for multiple analysis/forecast times and scenarios of interest. Estimating area performance with a uniform grid can neglect important environmental acoustic features or can over-compute in areas of environmental acoustic isotropy. Two methods are developed to pre-examine an area and time frame to assess environmental acoustic similarities for performance estimation with fewer acoustic model predictions and thus less computation time. The first method is based on critical factors in the environment that typically indicate acoustic response, and the second method is based on a more robust full waveguide mode-based description of the environment. Results are shown for the critical factors method and prove this to be a viable solution for most cases studied. The mode-based method is developed for range independent environments and shows significant promise for future development.