Michigan Corpus of Academic Spoken English

The Michigan Corpus of Academic Spoken English (MICASE) is a collection of nearly 1.8 million words of transcribed speech (almost 200 hours of recordings) from the University of Michigan (U-M) in Ann Arbor, created by researchers and students at the U-M English Language Institute (ELI). MICASE contains data from a wide range of speech events (including lectures, classroom discussions, lab sections, seminars, and advising sessions) and locations across the university.
http://quod.lib.umich.edu/m/micase/