Prosody is critical in conveying topic coherence and the salience of information in speech. In this study we propose that the overall coherence is brought about through pitch level structuring of phrases at both the local level of hierarchical phrase unit positioning and the global level of pitch baseline rise and fall as climax and resolution. Our results show that prosody has critical importance in the understanding and generation of natural conversation, and is crucial to enhance performance in topic segmentation, topic tracking, and advanced conversational synthesis and recognition.