In this work we propose a framework for speech understanding in Natural Language DB accessing based on the cooperative behaviour of the system which identifies its goals with user's goals and executes its own plans for satisfying these goals. The purpose of this work is to verify that in this particular human-machine interaction, by starting from some few recognized keywords, it is possible to reconstruct the user's goal and then to satisfy it The process of user's goal recognition is realized by a chart-based mechanism for plan recognition. This approach allows us to use the same formalism to represent both the low level (i.e. the syntactical analysis) and the high level (i.e. plan recognition) analyses.