Vocal tract analog synthesizer with lumped losses
Bernard Guérin, D. Degryse, Bruno Lherm · The Journal of the Acoustical Society of America · 1983
The vocal tract analog synthesizer generally requires a lot of calculation when a real signal is to be obtained. Thus, when you want to undertake studies, a real time synthesizer is more convenient. One way to carry out sound wave propagation modeling in the vocal tract is to consider the Kelly-Lochbaum model. In this case, we have to introduce a damping coefficient at the junction of the two elementary tubes. In order to decrease the computation size, we propose to concentrate the losses at three places along the vocal tract. These places are chosen so that the end characteristics (glottis, radiation) will not be disturbed. If there are about 20 elementary cells, the losses are places between cells number 2 and 3, 10 and 11, 14 and 15 (number 1 is next to the glottis). The simulation of this model, including the wall vibration and lip radiation according to the principle proposed by D. Degryse (The 4th F.A.S.E. symposium, Venezia, 193–196 (1981)], gives formant characteristics close to those of the distributed model: the maximum error is less than 1% on the first three formant frequencies and 20% on the respective bandwith. Then, the synthesizer requires about 25% fewer computations than without the improvement.