1. A speech analysis apparatus comprising: a first parameter processor configured to extract a pitch value from speech information; a second parameter processor configured to extract spectrum information from the speech information; a third parameter processor configured to extract a maximum voiced frequency and allowing boundary information for respectively filtering a harmonic component and a non-harmonic component to be obtained; a synthesizing processor configured to pseudo-synthesize speech by using the pitch value, the spectrum information, and the maximum voiced frequency which are extracted by the first parameter processor, the second parameter processor, and the third parameter processor, respectively; and a fourth parameter processor configured to extract a gain value by comparing energies of a harmonic component and a non-harmonic component synthesized by the synthesizing processor.