This paper proposes a new phase vocoder based method for shape invariant real-time modification of speech signals. The performance of the method with respect voiced and unvoiced signal components as well as the control of the voiced/unvoiced balance of the transformed speech signals will be discussed. The algorithm has been compared in perceptual tests with implementations of PSOLA, and HNM algorithms demonstrating a very satisfying performance. Due to the fact that the quality of transformed signals is remaining acceptable over a wide range of transformation parameters the algorithm is especially suited for real-time gender and age transformations.
Bibliographic reference. Röbel, Axel (2010): "Shape-invariant speech transformation with the phase vocoder", In INTERSPEECH-2010, 2146-2149.