1. A speech recognition system comprising: a context storage medium storing a monosyllabic command context including a plurality of monosyllabic commands and storing a polysyllabic command context including a plurality of polysyllabic commands; a speech segment detector detecting a speech segment having a start point and an end point by analyzing a speech signal within the speech segment; a syllable determiner configured determining whether the speech signal corresponds to a monosyllabic form or a polysyllabic form; a feature vector extractor extracting a feature vector by analyzing the speech signal; and a speech recognizer selecting one of the monosyllabic command context and the polysyllabic command context according to the determination of whether the speech signal corresponds to the monosyllabic form or the polysyllabic form and recognizing at least one command in the selected one of the monosyllabic command context and the polysyllabic command context based on the extracted feature vector.