On improving the intelligibility of synchronized over-lap-and-add (SOLA) at low TSM factor

We propose an algorithm to modify the synchronized overlap-and-add (SOLA) technique. SOLA is a popular technique for time scale modification of speech and audio signal. It changes the time scale of the signal while maintaining the pitch information. However, when the time scale of the signal is compressed more, the synthesized speech of SOLA has high articulations rate that it becomes almost impossible for the human ear to comprehend. The proposed algorithm can enhance the quality if the time scaled signal by using a time varying time scale factor which is locally adapted to the input signal. It is found that the intelligibility of the synthesized signal using the proposed algorithm is considerably better than the one synthesized from simple SOLA.