Better acoustic model of the vocal tract
Shinji Maeda · The Journal of the Acoustical Society of America · 1981
Speech signals were synthesized by assuming plane wave propagations and nonrigid vocal-tract walls. The tract is excited by specifying the time function of the glottal area. A constant air pressure source is assumed. The quality of 11 different French vowels synthesized was excellent in terms of naturalness as well as of intelligibility. It seems that this high quality is primarily due to a better realization of the source-tract interaction, especially the time-varying characteristics of the clottat impedance within each fundamental period. Interestingly the quality of nasal vowels or nasals was not satisfactory. We suspect that a simple acoustic tube is a rather poor representation of the nasal tract. Our theoretical analygig and also experiments by Lindqvist-Gauffin and Sundberg [“Acoustic Properties of the Nasal Tract,” Phonetica 33, 161–168 (1976)], suggests that the sinus shunt cavities within the nasal tract may play an important role in shaping appropriate nasal spectra. Results of simulation experiments will be demonstrated.