A method and apparatus for discriminating non-sounds and voiceless sounds of speech signals, recorded on a recording medium, from each other when playing back the speech signals at a varied play-back speed. The method includes the steps of setting, as a reference voltage level, an optional value between a voltage level corresponding to non-sounds and a voltage level corresponding to voiceless sounds, detecting a pitch component of each waveform of the speech signals, comparing the absolute value of a voltage level of the detected pitch component with the reference voltage level, and distinguishing and outputting a portion of the speech signal associated with the detected pitch component based on the result of the comparison. The apparatus includes a waveform splitter for splitting each waveform of the speech signals at a predetermined time interval, a level modulator for modulating the level of each split speech signal waveform to remove a DC component included in the speech signal waveform, a pitch detector for detecting the voltage level of a pitch component of each modulated speech signal waveform, a comparator for comparing the detected voltage level of the pitch component with a reference voltage level initially set, and a switch for selectively switching each split speech signal waveform on the basis of the result of the comparison.