This book has its origins in the Multimedia Communications Research Center at Bell Laboratories. It will likely be the last thing coming from this Center, since it no longer exists. This book reflects our vision on next-generation multimedia communication systems, shared by many researchers who worked with us at a time in the last several years in the Bell Labs’ Acoustics and Speech Research Department. Before falling apart in the recent relentless telecommunication firestorm, this department had a legendary history of producing ground-breaking technological advances that have contributed greatly to the success of fundamental voice and advanced multimedia communications technologies. Its scientific discoveries and innovative inventions made a remarkable impact on the cultures within both the industrial and academic communities. But due to the declining financial support from its parent company, Lucent Technologies, Bell Labs decided to lower, if not completely stop, the effort on developing terminal technologies for multimedia communications. As a result, many budding and well established acoustics and speech scientists left Bell Labs but soon resumed their painstaking and rewarding research elsewhere. Their spirit for innovation and passion for what they believe did not disappear; quite to the contrary it will likely live on (this book is the best evidence). The “flame” of their curiosity and enthusiasm will keep burning and will be transmitted to the next generation without a doubt. The idea of editing such a book was triggered early in 2003 when we discussed how to continue our ongoing collaboration after we could no longer work together in the same place. By inviting our former colleagues and collaborators to share their thoughts and state-of-the-art research results, we hope to bring the readers to the very frontiers of audio signal processing for next-generation multimedia communication systems.