The goal of this project is to utilize the results of conversational discourse analysis (e.g., prosody) to model pronunciation variations, and, more specifically, to investigate the use of a hidden speaking mode to represent systematic variations that are correlated with the word sequence (predictable from syntactic structure and thus includable into the language model). Possible systematic factors affecting pronunciation differences are local factors, such as coarticulation effects across word boundaries, linguistic factors, such as phrasing and focus (which are cued by prosodic markers that affect the acoustic realization of a word), speaking rate (which may be associated with discourse structure), and global factors, such as dialect.