My program of research uses a systems neuroscience approach to study the computations, maturational constraints, and plasticity underlying speech perception. Speech signals are multidimensional, acoustically variable, and temporally ephemeral. A significant computational challenge in speech perception (and more broadly, audition) is categorization, that is, mapping continuous, multidimensional, and variable acoustic signals into discrete, behavioral equivalence classes. Despite the enormity of this computational challenge, native speech perception is rapid and automatic. In contrast, learning novel speech categories is effortful, and is considered a challenging computational task for the mature brain. In this talk, I elucidate mechanisms underlying how novel speech categories are acquired and represented in the mature brain.