An auditory localization model based onhigh frequency spectral

We present in this paper a connectionist model that extracts interaural intensity di erences (IID) from head related transfer functions (HRTF) in the form of spectral cues to localize broadband high frequency auditory stimuli, both in azimuth and elevation. A novel discriminative matching measure (DMM) is de ned and optimized to characterize matching this IID spectrum. The optimal DMM approach as well as a novel back-propagation based fuzzy model of localization are shown to be capable of localizing sources in azimuth, using only spectral IID cues. The fuzzy neural network model is extended to include localization in elevation. The use of training data with additive noise provides robustness to input errors. Outputs are modeled as two dimensional Gaussians which act as membership functions for the fuzzy sets of sound locations. Error back-propagation is used to train the network to correlate input patterns and the desired output patterns. The fuzzy outputs are used to estimate the location of the source by detecting Gaussians using the max-energy paradigm. The proposed model shows that HRTF based spectral IID patterns can provide su cient information for extracting localization cues using a connectionist paradigm. Successful recognition in the presence of additive noise in the inputs indicate that the computational framework of this model is robust to errors made in estimating the IID patterns. The localization errors for such noisy patterns at various elevations and azimuths are compared and found to be within limits of localization blurs observed in humans. INDEXTERMS: auditory localization, pattern recognition, discriminativematchingmeasure (DMM), fuzzy neural networks, back-propagation MS: 94031 Revision: 3 1