1. A speech recognition system, comprising: a microphone receiving a noise signal of a moving object; a speed level classifier for measuring a moving speed of the moving object by using the noise signal at an initial time of speech recognition to determine a speed level of the moving object; a first speech enhancement unit for enhancing sound quality of an input speech signal of the speech recognition by using a Wiener filter, if the speed level of the moving object is equal to or lower than a specific level; and a second speech enhancement unit enhancing the sound quality of the input speech signal of the speech recognition by using a Gaussian mixture model, if the speed level of the moving object is higher than the specific level.
1. A speech recognition system, comprising: a microphone receiving a noise signal of a moving object; a speed level classifier for measuring a moving speed of the moving object by using the noise signal at an initial time of speech recognition to determine a speed level of the moving object; a first speech enhancement unit for enhancing sound quality of an input speech signal of the speech recognition by using a Wiener filter, if the speed level of the moving object is equal to or lower than a specific level; and a second speech enhancement unit enhancing the sound quality of the input speech signal of the speech recognition by using a Gaussian mixture model, if the speed level of the moving object is higher than the specific level. 2. The speech recognition system of claim 1 , wherein the speed level classifier includes: a feature extraction unit for calculating a mean log-scale energy value of a specific number of frames, excluding frames having maximum and minimum log-scale energy values, at the initial time of the speech recognition; and a level classification unit for classifying the speed level of the moving object based on the mean log-scale energy value by using maximum and minimum thresholds.