Like all living systems, auditory system function is constantly changing in response to internal and external forces—genetic, disease, and experience. It has long been recognized, for example, that the fundamental measure of hearing, the pure-tone audiogram, is susceptible to both developmental and learning influences. And the deterioration of hearing sensitivity in later life is thought to be influenced by inheritance, acting synergistically with environmental (noise, toxins) and biological (ageing) processes. Research into the long-term dynamics of hearing is, despite much increased effort and under- standing over recent years, still in its infancy. The organization of this chapter mimics the history of research in the field. While we provide an overview of the most significant, older findings, the primary focus of our presentation is on the recent and, we think, exciting findings of the last decade. The bias of our work reflects our backgrounds, in experimental psychology and neuroscience. Those seeking alternative perspectives are directed to appropriate reviews in the overview that follows.