12. A speech recognition system including at least one processing device, the system comprising: a change detector to detect, using the at least one processing device, energy changes between a plurality of frames distinguishing portions of a signal, each of the plurality of frames having lengths less than a whole time length of the signal; and a determiner to identify speech segments and/or non-speech segments from the plurality of frames based on the detected energy changes between the plurality of frames by assigning a predetermined weight to a segment in which an energy level of a respective frame is changed and when an energy difference exists between two neighboring frames.
17. The system of claim 12 , further comprising a combiner to combine the identified speech segment with other speech and/or non-speech segments of the signal.