Synthesis of unseen context and spectral and pitch contour smoothing in concatenated text to speech synthesis

The availability and perceptual clarity of speech units, and how these units are put together during synthesis have always been the cornerstones of any high quality concatenative text-to-speech synthesis (TTS) system. The speech units are usually obtained from different sentences and contexts in a speaker-dependent speech database. One of the problems with speech units obtained this way is the occurrence of unseen contexts. Here, unseen contexts denote phonological sequences that are not acoustically represented in the selection pool during synthesis. Unseen units are expected in any concatenative TTS system because it is difficult to obtain an: acoustic representation of all possible existing contexts that could occur in speech. This paper proposes a pitch synchronous, overlap and merge method to synthesise the acoustic representation of unseen contexts from existing similar units found in the inventory. It also gives a brief description of spectral and pitch contour smoothing across concatenated units.