Combining Speech User Interfaces of Different Applications Dissertation An der Fakultät für Mathematik, Informatik und Statistik der Ludwig-Maximilians-Universität München von Dongyi Song Tag der Einreichung: 16.11.2006 Erster Berichterstatter: Prof. Dr. Heinrich Hußmann (Ludwig-Maximilians-Universität München) Zweiter Berichterstatter: Prof. Dr. Dietrich Klakow (Universität des Saarlandes) Tag des Rigorosums: 13.12.2006 Acknowledgements This doctoral thesis would not have been able to reach this final stage in less than three years without the continuous support I have had from many people. I would like to express my profound gratitude to all of them. Especially, I would like to express my deepest gratitude to Prof. Dr. Heinrich Hußmann, who is not only the supervisor and first referee of my thesis but also a good advisor in many aspects of my life. Without his belief in my skills and his numerous ideas this work would not have been realized. He gave me a great deal of invaluable advice leading me to the right way in times of doubt. This work could not have been carried out without the wholehearted cooperation of Siemens AG.