Research on auditory development intensified in the mid-1970s, expanding our understanding of auditory processes in infants and children. Recent comprehensive reviews of this literature include those by Aslin, Jusczyk, and Pisoni (1998), Werner and Marean (1996), and Werner and Rubel (1992). Two recurrent issues are whether the limitations of testing methods cause true abilities to be underestimated, and whether auditory development is substantially complete during infancy or continues into childhood.