Using voice conversion as a paradigm for analyzing breathy singing voices

It is generally thought that breathiness can be added to voices by modifying the glottal source within a source-filter model. However, this does not work well when the original voice is very different from the desired breathy voice. In this experiment, a voice conversion algorithm is used to investigate the relationship between the glottal source and the vocal tract filter. The LPC residual from one voice is fed into the LPC filter of another voice. According to a source-filter theory of the voice, the synthesized voice should take on the glottal quality of the LPC source. This hypothesis is evaluated through a perceptual test with a linguistics expert. The results suggest that the vocal tract does have an influence on the perception of breathy voices. Given the narrow nature of this experiment, further testing is recommended to verify these results.