Natural spontaneous speech is so ambiguous that a system for understanding it requires the cooperation of many knowledge sources. Thus, in order to integrate speech processing and language processing, it is necessary to provide a system with a mechanism for supporting such cooperation. We propose here a general framework for cooperative problemsolving, based on the blackboard model and a TMS (truth maintenance system), with an enhanced proving function. In this framework, a reasonably consistent interpretation is automatically kept on the blackboard, while each knowledge source performs its own inference and puts the results on the blackboard. Based on this framework, a model has been established for a system which can understand spontaneous speech through the cooperation of independent knowledge sources. Most notably, prosodic information is used as suprasegmental cues to infer the structure of spontaneous speech. This allows robust parsing of spoken sentences. The feasibility and validity of our basic framework have been confirmed by computer simulation experiments on spontaneous speech.