Abstract: A computer implemented apparatus and method for modifying the playback rate of a previously stored audio or voice data file stored within a computer system without altering the pitch of the audio data file as originally stored. The present invention also maintains a high level of sound quality during playback. The present invention includes a double buffering system in order to perform all of the desired calculations in real time. A time stretching technique is employed upon the audio data file to decrease or increase playback rate which creates audio segments requiring joining processing. Junctions are smoothed by employing a cross-fade amplitude envelope filter and a compressor/limiter is used to maintain filter range. The system may operate on a desktop computer allowing for advantageous playback and audio data management options of stored voice and or sound data.