This book constitutes the refereed proceedings of the 4th IEEE Tutorial and Research Workshop on Perception and Interactive Technologies for Speech-Based Systems, PIT 2008, held in Kloster Irsee, Germany, in June 2008. The 37 revised full papers presented together with 1 invited keynote lecture were carefully selected from numerous submissions for inclusion in the book. The papers are organized in topical sections on multimodal and spoken dialogue...