15. A speech recognition method comprising: detecting a speech segment having a start point and an end point by analyzing a speech signal within the speech segment; determining whether the speech signal corresponds to a monosyllabic form or a polysyllabic form; extracting a feature vector by analyzing the speech signal; calculating initial confidence scores of respective monosyllabic commands included in a monosyllabic command context and initial confidence scores of respective polysyllabic commands included in a polysyllabic command context based on the extracted feature vector; setting a first weight value which is to be applied to the initial confidence scores of the respective monosyllabic commands and a second weight value which is to be applied to the initial confidence scores of the respective polysyllabic commands according to the determination of whether the speech signal corresponds to the monosyllabic form or the polysyllabic form; and calculating final confidence scores of the respective monosyllabic commands by applying the first weight value to the initial confidence scores of the respective monosyllabic commands and final confidence scores of the respective polysyllabic commands by applying the second weight value to the initial confidence scores of the respective polysyllabic commands.
15. A speech recognition method comprising: detecting a speech segment having a start point and an end point by analyzing a speech signal within the speech segment; determining whether the speech signal corresponds to a monosyllabic form or a polysyllabic form; extracting a feature vector by analyzing the speech signal; calculating initial confidence scores of respective monosyllabic commands included in a monosyllabic command context and initial confidence scores of respective polysyllabic commands included in a polysyllabic command context based on the extracted feature vector; setting a first weight value which is to be applied to the initial confidence scores of the respective monosyllabic commands and a second weight value which is to be applied to the initial confidence scores of the respective polysyllabic commands according to the determination of whether the speech signal corresponds to the monosyllabic form or the polysyllabic form; and calculating final confidence scores of the respective monosyllabic commands by applying the first weight value to the initial confidence scores of the respective monosyllabic commands and final confidence scores of the respective polysyllabic commands by applying the second weight value to the initial confidence scores of the respective polysyllabic commands. 16. The speech recognition method of claim 15 , wherein the determining of whether the speech signal corresponds to the monosyllabic form or the polysyllabic form comprises: detecting a vowel and a consonant from the speech signal; calculating a number of combinations of the vowel and the consonant; and comparing the number of combinations to a predetermined number.