Improved vocal tract model for speech synthesis

Speech synthesis of nasal and non-nasal speech sounds are studied on the basis of an improved model where a nasal tract is included in the vocal tract. The transfer function of the model is analysed. Because of the closure of the oral tract, the three-port adaptor at the velum is reduced to a two-port adaptor, so that the model parameters can be estimated by inverse filtering from the speech signal. Moreover this method is applied to investigate nasalization of vowels.