Time-Scale Modification Using Fuzzy Epoch-Synchronous Overlap-Add (FESOLA)

A modification to the Epoch-Synchronous Overlap-Add (ESOLA) Time-Scale Modification (TSM) algorithm is proposed in this paper. The proposed method, Fuzzy Epoch-Synchronous Overlap-Add, improves on the previous ESOLA method through the use of cross-correlation to align time-smeared epochs before overlap-adding. This reduces distortion and artefacts while the speaker's fundamental frequency is stable, as well as reducing artefacts during pitch modulation. The proposed method is tested against well known TSM algorithms. It is preferred over ESOLA, and gives similar performance to other TSM algorithms for voice signals. It is also shown that this algorithm can work effectively with solo instrument signals containing strong fundamental frequencies. Full implementation of the proposed method and zero frequency resonator can be found at github.com/zygurt/TSM.