J. K. (Jack) Chambers is Professor of Linguistics at the University of Toronto. He is the author of Sociolinguistic Theory: Linguistic Variation and Its Social Significance (third edition, 2009), co-editor with Natalie Schilling of The Handbook of Language Variation and Change (second edition, 2013) and co-author, with Peter Trudgill, of Dialectology (second edition, 1998), as well as other books and scores of articles. He works extensively as a forensic consultant and maintains a parallel vocation in jazz criticism, including the prize-winning biography Milestones: The Music and Times of Miles Davis (1998), Bouncin' With Bartok: The Incomplete Works of Richard Twardzik (2008), and Tan Fantasies and Indigo Moods: Duke Ellington's Music in Fourteen Themes.