These past four years have been a wonderful experience for me. I could not have completed this work successfully without the love and support from a lot of people around me. Firstly, I would like to express my sincere thanks to my supervisor Dr. Chng Eng Siong (Nanyang Technological University, NTU) and co-supervisor Dr. Lee Siu Wa (Institute for Infocomm Research, I 2 R) for their support and advice. Their suggestions and discussions helped me to overcome the difficulties in my research. I would also like to express my appreciation to Prof. Li Haizhou and Dr. Wu Zhizheng for all their guidance and collaboration. They were like co-supervisors to me, discussing research ideas and revising conference and journal papers, which are the important parts of my Ph.D research. Moreover, I also want to thank to my colleagues in Human Language Technology department of I 2 R for their generous help. Also, thanks to all my colleagues at speech team and NTU-UBC Research Center of Excellence in Active Living for the Elderly (LILY) in NTU. It is a great pleasure to meet all these friends and discuss different technical aspects of the project and research work.