https://web.archive.org/web/20240731004804if_/https://www.tdx.cat/bitstream/handle/10803/7555/tjbs.pdf?sequence=1&isAllowed=y I've been working on reading through the paper "Voice Processing and Synthesis by Performance Sampling and Spectral Models" and have started to implement it. It seems as if most if not all of the relevant patents have expired. I will post any updates here.