Synthesizing expressive speech from amateur audiobook recordings

Freely available audiobooks are a rich resource of expressive speech recordings that can be used for the purposes of speech synthesis. Natural sounding, expressive synthetic voices have previously been built from audiobooks that contained large amounts of highly expressive speech recorded from a profes- sionally trained speaker. The majority of freely available au- diobooks, however, are read by amateur speakers, are shorter and contain less expressive (less emphatic, less emotional, etc.) speech both in terms of quality and quantity. Synthesiz- ing expressive speech from a typical online audiobook there- fore poses many challenges. In this work we address these challenges by applying a method consisting of minimally su- pervised techniques to align the text with the recorded speech, select groups of expressive speech segments and build expres- sive voices for hidden Markov-model based synthesis using speaker adaptation. Subjective listening tests have shown that the expressive synthetic speech generated with this method is often able to produce utterances suited to an emotional mes- sage. We used a restricted amount of speech data in our exper- iment, in order to show that the method is generally applicable to most typical audiobooks widely available online. QC 20160422