Modeling normal and hearing-impaired monaural and binaural signal detection in the presence of noise

Abstract

Psychoacoustical investigations have demonstrated that monaural and binaural signal detection is affected by existence of distracting noise. The most prominent phenomena are co-modulation masking release (CMR) in monotic listening, and binaural masking level difference (BMLD) in diotic listening. Both CMR and BMLD are significantly deteriorates in hearing-impaired listeners. Both CMR and BMLD phenomena are tested by a complete model of the auditory system for normal and hearing-impaired systems. Prediction of the amplitude discrimination results are obtained by deriving the Cramer Rao lower bound (CRLB) of the neural activity. The auditory system model includes a complete cochlear model with integrated outer hair cells and tectorial membrane; an inner hair cell-synapse model that transduce the cilia motion to auditory nerve instantaneous rate; Inferior Colliculus that receives inputs from both ears and process them by excitatory-inhibitory (EI) cells. The AN activity is considered as a non-homogeneous Poisson process (NHHP). We have recently showed that EI cells are NHHP as well, if their inputs behave as NHHP. Therefore, CRLB can be derived analytically from both AN and IC outputs. We have successfully predicted major CMR and BMLD properties as a function of frequency and noise properties for normal and impaired auditory system.