Growing evidence shows that individual differences among listeners with normal hearing thresholds reflect underlying differences in how well the auditory system encodes temporal features of sound. In the laboratory, these differences manifest in a range of psychophysical tasks. In everyday life, however, the situations that reveal these differences are often social settings where listeners are trying to understand one talker in the presence of other competing sound sources (the “cocktail party” setting). Physiologically, the brainstem’s envelope-following response (a specific form of the frequency-following response) correlates with individual differences in behavior. Motivated by both animal and human studies, this chapter reviews the evidence that behavioral and physiological differences across individual listeners with normal hearing thresholds reflect differences in the number of auditory nerve fibers responding to sound despite normal cochlear mechanical function (cochlear neuropathy). The chapter also points out some of the measurement issues that need to be considered when designing experiments trying to probe these kinds of individual differences in coding of clearly audible, supra-threshold auditory information.