Concept Extraction from Conversational Speech using Segment Graphs

In this paper, a concept extraction method, an important element in spoken dialog systems when the nature of users´ spoken queries are unstructured, is proposed and tested in a Thai automated international telephone call inquiry service. The method unifies concept constraints with other constraints, ranging from acoustic to language constraints, in a single segment-based probabilistic framework. With concept knowledge available, un-recalled keywords are reduced by 37%. Regarding concept extraction and goal identification, the proposed method is shown to be superior to the baseline system. Concepts are extracted at more than 80% of both recall and precision rates.