A Shape-invariant Phase Vocoder for Speech Transformation

This paper proposes a new method for shape invariant realtime modification of speech signals. The method can be understood as a frequency domain SOLA algorithm that is using the phase vocoder algorithm for phase synchronization. Compared to time domain SOLA the new implementation provides improved time synchronization during overlap add and improved quality of the noise components of the transformed speech signals. The algorithm has been compared in two perceptual tests with recent implementations of PSOLA and HNM algorithms demonstrating a very satisfying performance. Due to the fact that the quality of transformed signals stays constant over a wide range of transformation parameters the algorithm is well suited for real-time gender and age transformations.