Fricative production modelling: aerodynamic and acoustic data

The aerodynamic and acoustic phenomena involved in the production of fricative consonants are far from being completely understood. The overall Ievel and spectral characteristics of the radiated sound pressure are known to primarily depend on the aerodynamic state of the vocal tract, i.e. the pseudo-static pressure drop across the main oral constriction and the cross-sectional area of the constriction. The first part of this paper describes an attempt to establish some quantitative relationships, based upon experimental measurements carried out on a human subject, both for sustained and dynamic voiceless fricatives. The second part of the paper focuses on the acoustic modeHing of the vocal tract in the frequency domain ; it describes our attempts to match some measured spectra with transfer functions computed from simplified area functions, and the influence of different parameters on these spectra. We show, among other things, that the obstacle effect can be explained in terms offilter characteristics.