A TD-PSOLA based method for speech synthesis and compression

Mobility and cost restrictions of current text-to-speech systems stop them from being used by people with speech impairments all over the world. Therefore new ways to improve mobility and lower cost have to be developed. This can be done by decreasing the computational resources used by speech synthesis systems. Non-parametric concatenative synthesis techniques provide the easiest way to generate artificial speech with high quality. Although, they can be, in general, computationally efficient (e.g., TD-PSOLA) they are not always suited for implementation on embedded devices because they require rather large recorded speech data-bases. A big part of the recorded speech data is represented by the samples of the vowels. Therefore, compression ratios of at least 25% can be achieved for Romanian, by removing all these samples but one overlap-add (OLA) frame. At synthesis, the remaining vowel is used to generate the original sound. The paper presents a new method for the generation and the compression of vowels, starting from only one OLA frame and using TD-PSOLA in new way. Experiments show that by appropriately choosing pitch and amplitude jitter models, high quality synthetic speech can be achieved.