The materials here are from the sociophonetics course run by Erik R. Thomas at North Carolina State University in Fall 2011. All users are free to download and copy these files, in part or in whole, for educational purposes.
Textbook: Sociophonetics: An Introduction | supporting website
Course Syllabus: PDF | Word Doc
Lecture Powerpoint Slides (available in PPTX format, for download):
Answers to Vowel Plots (Word Doc)