Introduction

This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part deals with compensation for or simulation of reduced dynamic range. It reviews early work of J. Fletcher and his colleagues on loudness and loudness recruitment, and updates this work by incorporating modern-day physiological information. The part explores the use of the inverse of compression—expansion—as a means of simulating sensorineural hearing loss of cochlear origin. It focuses on the simulation of speech-identification errors for two listeners with cochlear impairment using spectrally shaped masking noise as the means of hearing-loss simulation. The part describes a real-time implementation of a multichannel expander and present hypothetical results on a variety of psychoacoustic tasks expected for normal listeners when using this simulator.