A NUMERICAL-SIMULATION OF THE EFFECTS OF THE ACTUAL LIP GEOMETRY ON ACOUSTIC FIELDS BY A 3-DIMENSIONAL FEM

This paper describes an implementation of the finite element method to examine the effects of actual lip shape on the sound radiation. A thr ee-dimensional finite element approach by Galerkin method was used. Th e accuracy of the calculation of finite element method for the sound r adiation was tested by comparing it with the exact solutions for a cir cular piston radiator on an infinite baffle. Using a set of finite ele ment models of the vocal tract, we calculated the responses to a pure tone input and the sound fields over the frequency range of 100 Hz-7 k Hz. The transfer functions are examined in detail for vowels /a/ and / i/ when the shape of the actual lips is simplified as a plane-radiatio n surface. The effects of lip shape on the distribution of sound press ures are also shown in both the vocal tract and the surrounding space of the mouth opening.