DETERMINATION OF THE VOCAL TRACT SPECTRUM FROM THE ARTICULATORY MOVEMENTS BASED ON THE SEARCH OF AN ARTICULATORY-ACOUSTIC DATABASE

This paper presents a method for determining the vocal-tract spectrum from the positions of fixed points on the articulatory organs. The method is based on the search of a database comprised of pairs of articulatory and acoustic data representing the direct relationship between the articulator position and vocal-tract spectrum. To compile the database, the electro-magnetic articulograph (EMA) system is used to measure the movements of the jaw, lips, tongue, velum, and larynx simultaneously with speech waveforms. The spectrum estimation is accomplished by selecting database samples neighboring the input articulator position and interpolating the selected samples. In addition, phoneme categorization of the input position is performed to restrict the search area of the database to portions of the same phoneme category. Experiments show that the mean estimation error is 2.24 dB and the quality of speech synthesized from the estimated spectrum can be improved by using the phoneme categorization.