Singing voice synthesis in Spanish by concatenation of syllables based on the TD-PSOLA algorithm

摘要

The present work shows the development of a Spanish singing voice synthesizer where a TD-PSOLA algorithm is applied. The main goal of the development was to test the hypothesis that while diphones are linguistically the units with the best intelligibility-flexibility compromise for the purposes of spoken voice synthesis, it is the syllables the best suited units for concatenation singing voice synthesis. Such hypothesis is particularly strong for Spanish, since its rules for syllable construction are comprehensive, relatively simple, and only a handful. To test the hypothesis a relatively small amount of vocals and syllables in Spanish were recorded by a soprano singer at both F4 and C5 tones, with duration of 1 second each (±0.2sec.). The modification of the syllables was carried only in regards to tone and duration. Matlab was used as the programming platform mainly because of the author's relative expertise on it. To evaluate the performance of the system several melodic tasks were asked of it including the singing of a popular Mexican song (Las Mananitas). Results show that a highly intelligible synthesized Spanish singing voice based on syllable concatenation can be achieved with minimum control mechanisms. While the time duration variation introduces very few noticeable digital errors, a transposition of up to a just fourth was possible without generating very obvious digital errors. A variation of 5% (0.05) in the frequency scale corresponds to a semitone variation in the equally tempered modern scale.