33. A system adjusting a voice prompt based upon a state of a user of the system, the system comprising: a signal processing module for obtaining utterance parameters from utterance received from the user, the utterance parameters indicating the state of the user; an utterance parameter vector generation module for generating an utterance parameter vector based upon the obtained utterance parameters; a user state determination module for converting the utterance parameter vector to an indication representing the state of the user and determining the state of the user based upon the indication; and a speech synthesizer module for generating an audio waveform of the voice prompt based upon the determined state of the user, wherein the signal processing module obtains the utterance parameters by: partitioning the utterance into segments; and assigning one of a plurality of classifications to each segment, each classification corresponding to at least one of a plurality of states of the user, wherein the utterance parameter vector generation module generates the utterance parameter vector by: determining the number of segments for each classification; and dividing the number of segments for each classification by a total number of segments in the utterance.
39. The system of claim 33 , wherein the speech synthesizer module generates the audio waveform of the voice prompt having prosody that is consistent with the determined state of the user.