HMM-based text to speech system with speaker interpolation

Hidden Markov Model (HMM) based text-to-speech (TTS) systems offer many advantages compared to the concatenative approach. One of those advantages is the ability to interpolate between different speakers to generate new voices. In this paper, speaker interpolation for HMM-based TTS (HTS) is described and listening test results for the interpolation of English and Turkish voices are presented. Similar to English, we obtained Turkish speech that strongly reflect the interpolation ratio in perceptual similarity. Some insight into the interpolation process is also provided by analysing the spectra of the reference and final voices.