Human listeners demonstrate remarkably robust speech perception despite being faced with a speech signal that is highly variable. In this talk, I will briefly consider the sources of variability that affect the speech signal and highlight the central issue for any account of speech perception. I will then provide an overview of the kind of questions we address in our lab by discussing past work in different domains of speech variability. Finally, I will report on a new paradigm that we are working on that takes seriously the collaborative nature of spoken language processes.