1. A speech recognition apparatus for receiving and recognizing a speech signal from a speaker comprising: an acoustic analysis means for analyzing a speech signal acoustically; a feature extraction means for extracting characteristic parameters from the speech signal based on a result of the analysis performed by the acoustic analysis means; and a pattern matching means for performing pattern matching between each of reference patterns in a vocabulary and the extracted characteristic parameters and selecting as candidate words at least one word corresponding to the reference pattern which has a high similarity with the characteristic parameters, the vocabulary being stored beforehand and including the reference patterns corresponding to words, wherein the pattern matching means outputs as a result of recognition at least one word other than a specific word if the candidate words include the specific word and a level of confidence that the speech signal actually represents the specific word is low, and wherein the pattern matching means is connected to an external device, and the external device receives and uses the result of recognition from the pattern matching means for controlling an operation of the external device.