Use of parallel recognizers for robust in-car speech interaction

This paper refers to an activity under way at the speech recognition technology level for the development of a hands-free dialogue interaction system in the car environment. The use of a set of HMM recognizers, running in parallel, is being investigated in order to ensure low complexity, modularity, fast response, and to allow a real-time reconfiguration of the language models and grammars according to the policy indicated by natural language understanding and dialogue manager modules. A corpus of spontaneous speech interactions was collected using the Wizard-of-Oz method in a real driving situation with a microphone placed far from the driver. The use of parallel recognition units, each specialized on a given geographical domain, was explored using the resulting real corpus. Experiments show the advantage of selecting the recognized sentence according to the maximum likelihood among the active units when compared to the use of a single language model based on a very large vocabulary.