[Influences of acoustic coupling between source and vocal tract of the Fo of oral vowels. Consequence for the study of intrinsic characteristics].

With the aid of a two-mass model of the vocal source loaded by the input impedance of the vocal tract, we first study theoretically, then by simulation, the effects of source-vocal tract coupling on the intrinsic frequencies Fo of the French oral vowels. We explain the correlation which exists between Fo and the frequency of the first formant as well as the results from the experiment described by Ishizaka and Flanagan [1972]. In conclusion, we show that the acoustic coupling cannot explain the different values of Fo, intrinsic in the vowels, but on the contrary, a physiological coupling has to compensate for the effects of acoustic coupling to explain the characteristics revealed in natural speech.