Noise source models for fricative consonants
Hybrid source models for fricative consonants are derived based on aeroacoustic principles of sound generation employing vocal tract area functions obtained from magnetic resonance imaging data of voiced and unvoiced English fricatives. Results based on data from a male and a female subject indicate that a linear source-filter model is fairly adequate for capturing essential spectral characteristics of sustained voiced and unvoiced strident fricatives below 10 kHz. The hybrid source models employ a combination of acoustic monopole and distributed dipole sources, and a voice source in the case of the voiced fricatives. The number of sources, source locations, and spectral characteristics and the relative source levels are chosen based on an analysis-by-synthesis approach and are motivated by aeroacoustic theory of speech production. The resulting model is computationally efficient and can be readily used for synthesis.