1. A computer implemented method for indexing and retrieving documents stored in a database, comprising the steps of: extracting a document feature vector from each of a plurality of documents; indexing each of the plurality of documents according the associated document feature vector; converting a spoken query to an intermediate representation representing possible sequential combinations of terms in the spoken query; generating a query certainty vector from the intermediate representation; acquiring other information; combining the other information with the query certainty vector; and comparing the query vector and the other information to each of the document feature vectors to retrieve a ranked result set of documents.