Decapitation and Recapitation, a Study of Voice Quality
Joan E. Miller · The Journal of the Acoustical Society of America · 1964
The familiar model of the speech spectrum as a product of the source spectrum times the vocal-tract transfer function suggests making an actual separation of the two for two different talkers followed by a recombining of the vocal tract of one talker with the source of the other. The calculations to effect such an interchange were made on a pitch-synchronous basis. Fourier coefficients were obtained for each period, the harmonic-amplitude spectrum was matched to obtain locations of the vocal tract poles, and these poles were divided from the spectrum. The pole data for an utterance by one talker could thus be recombined with the source spectral data for an utterance by another talker and the speech wave regenerated by Fourier synthesis. Source data for several talkers were tried, each with the same vocal tract and also a single source was applied to several “heads.” Listening tests were made of the resulting combinations in an attempt to determine the effect of glottal source versus vocal tract on speech quality and talker identification.