A template-driven generation of prosodic information is proposed for Chinese text-to-speech conversion. A set of monosyllable-based synthesis units is selected from a large continuous speech database. The speech database is employed to establish a word-prosody-based template tree according to the linguistic features: tone combination, word length, part-of-speech (POS) of the word, and word position in a sentence. This template tree stores the prosodic features including pitch contour, average energy, and syllable duration of a word for possible combinations of linguistic features. Two modules for sentence intonation and template selection are proposed to generate the target prosodic templates. The experimental results for the TTS conversion system showed that synthesized prosodic features quite resembled their original counterparts for most syllables in the inside test. Evaluation by subjective experiments also confirmed the satisfactory performance of these approaches.

A novel two-level method is proposed for rapidly and accurately computing the line spectrum pair (LSP) frequencies. An efficient decimation-in-degree (DID) algorithm is also proposed in the first level, which can transform any symmetric or antisymmetric polynomial with real coefficients into the other polynomials with lower degrees and without any transcendental functions. The DID algorithm not only can avoid prior storage or large calculation of transcendental functions but can also be easily applied toward those fast root-finding methods. In the second level, if the transformed polynomial is of degree 4 or less, employing closed-form formulas is the fastest procedure of quite high accuracy. If it is of a higher degree, a modified Newton-Raphson method with cubic convergence is applied. Additionally, the process of the modified Newton-Raphson method can be accelerated by adopting a deflation scheme along with Descartes rule of signs and the interlacing property of LSP frequencies for selecting the better initial values. Besides this, Horner's method is extended to efficiently calculate the values of a polynomial and its first and second derivatives. A few conventional numerical methods are also implemented to make a comparison with the two-level method. Experimental results indicate that the two-level method is the fastest one. Furthermore, this method is more advantageous under the requirement of a high level of accuracy.