1. A speech recognition system comprises; a sound signal processor configured to acquire a sound signal from an object, and to calculate a sound signal parameter based on the acquired sound signal; an electromyographic signal processor configured to acquire potential changes on a surface of the object as an electromyographic signal, and to calculate an electromyographic signal parameter based on the acquired electromyographic signal; an image information processor configured to acquire image information by taking an image of the object, and to calculate an image information parameter based on the acquired image information; a speech recognizer configured to recognize a speech signal vocalized by the object, based on the sound signal parameter, the electromyographic signal parameter and the image information parameter; and a recognition result provider configured to provide a result recognized by the speech recognizer.