18. The method of claim 13 , wherein the comparing the detected user's voice signal with voice signal patterns from at least one model comprises calculating a first probability that the user's voice matches the voice patterns in a first model, and calculating a second probability that the user's voice matches the voice patterns in a second model.
18. The method of claim 13 , wherein the comparing the detected user's voice signal with voice signal patterns from at least one model comprises calculating a first probability that the user's voice matches the voice patterns in a first model, and calculating a second probability that the user's voice matches the voice patterns in a second model. 22. The method of claim 18 , wherein the second model accumulates voice patterns which do not correspond to the predetermined words.