8. The method of applying a multi-state barge-in acoustic model in a spoken dialog system, the method comprising: presenting a prompt to a user from the spoken dialog system; receiving an audio speech input from the user during the presentation of the prompt; accumulating the audio speech input from the user; applying a non-speech component having at least two one-state Hidden Markov Models (HMMs) to the audio speech input from the user; applying a speech component having at least five three-state HMMs to the audio speech input from the user, wherein each of the five three-state HMMs represents a different phonetic category; determining whether the audio speech input is a barge-in-speech input from the user; and if the audio speech input is determined to be the barge-in-speech input from the user, terminating the presentation of the prompt.
9. The method of claim 8 , wherein each of the phonetic categories comprises vowels and glides, unvoiced fricatives, voiced fricatives, other consonants and nasals.