High quality time-scale modification of speech using a peak alignment overlap-add algorithm (PAOLA)

The duration of a speech passage can be altered using audio time-scale modification techniques. Time-scale modification can be achieved in the time domain by segmenting the input signal into overlapping frames and recombining the frames with an overlap differing from the analysis overlap. We present a time-scale modification algorithm that uses a simple peak alignment technique to synchronize overlapping synthesis frames. The peak alignment overlap-add (PAOLA) algorithm also takes advantage of waveform properties to ensure a high quality output for the minimum number of iterations. The new algorithm produces a time-scaled output of approximately equal quality to that of an adaptive implementation of the commercially popular synchronised overlap-add (SOLA) algorithm, but offers a computational saving ranging from a factor of 15 (for a time-scale factor of 0.5) to 170 (for a time-scale factor of 1.1).