4. The voice recognition apparatus according to claim 2 , wherein the vocabulary dictionary managing unit selectively performs one of operations (1) and (2) below according to the extraction criterion information stored in the extraction criterion information storing unit: (1) the vocabulary dictionary managing unit extracts the recognition target words based on the scale information, (2) the vocabulary dictionary managing unit extracts all the words stored in the vocabulary dictionary storing unit as the recognition target words regardless of the scale information.
2. The voice recognition apparatus according to claim 1 , wherein the monitor control unit monitors at least one monitor target from a processing state of an operation accepted from a user, a processing state of the voice accepted from the user and a predetermined time passed from a measurement unit for measuring a time, the vocabulary dictionary managing unit increases or decreases the number of the recognition target words to be extracted from the plurality of words stored in the vocabulary dictionary storing unit according to the changed extraction criterion information, and the matching unit calculates the degree of matching with the recognition target words increased or decreased in number using the feature value converted by the voice analyzing unit.