In language evolution research, the use of computational and experimental methods to investigate the emergence of structure in language is exploding. In this review, we look exclusively at work exploring the emergence of structure in speech, on both a categorical level, and a combinatorial level. We show that computational and experimental methods for investigating population-level processes can be effectively used to explore and measure the effects of learning, communication and transmission on the emergence of structure in speech. We also look (...) at work on child language acquisition as a tool for generating and validating hypotheses for the emergence of speech categories. Further, we review the effects of noise, iconicity and production effects. (shrink)