Hani Yehia Fumitada Itakura Determination of human vocal-tract dynamic geometry from formant trajectories using spatial and temporal Fourier analysis. 477-480 1994 ICASSP (1) https://doi.org/10.1109/ICASSP.1994.389252 https://doi.ieeecomputersociety.org/10.1109/ICASSP.1994.389252 conf/icassp/1994 db/conf/icassp/icassp1994.html#YehiaI94