A Time-Scale Modification Algorithm Based on the Subband Time-Domain Technique for Broad-Band Signal Applications
Roland K. C. Tan, Amerson H. J. Lin · Journal of the Audio Engineering Society · 2000
Time-domain digital time-scale modification algorithms based on the overlap-and-add technique were developed mainly for speech signal applications and may not perform equally well for broad-band audio signals. Broad-band audio signals in general do not have a single pitch period or similar structure to take advantage of, as exists in single-talker speech. Due to the basic assumption of quasi-periodicity in such methods, this means that the best alignment point between two successive frames in the overlapping region may not always be ideal. It results in distortion in the form of repetitive waveforms, which produce echo and stuttering effects that are audible, especially after time-scale expansion. To overcome this problem, the broad-band signal is first divided into smaller subbands before the overlap-and-add technique is applied. The proposed subband analysis synchronous overlap-and-add (SASOLA) algorithm provides an alternative for time-scale modification of broad-band audio and speech signal applications without the various undesirable artifacts and high computational cost associated with the frequency-domain techniques.