variavel0=RODRIGO AVELINO MESQUITA DOS SANTOS - rodrigo.avelino@bol.com.br UNB FRANCISCO RICARDO DA CUNHA - frcunha@unb.br UNB Aldo João Sousa - aldo@unb.br UNB Abstract. The aim of this work is to examine the dynamical response of a spherical oscillatory bubble immersed in a suspension composed of a viscous fluid and anisotropic particles. These particles can be long fibers or macromolecules of high molecular weight. The bubble is composed of an ideal gas and it is set into motion growing and contracting in an acoustic pressure field. The effect of the hydrodynamic interaction between pairs of these particles for semi-dilute regime is investigated. Local orientation of the fibers is quantified by means of a probability density function. For a suspension of neutrally buoyant particles free of inertia and Brownian motion the local fiber orientation follows a Fokker-Planck equation. Numerical results of the bubble response to an acoustic pressure field are obtained for both situations: particles aligned to radial motion and for an initially random orientation of particles that involves in time. It is predicted that the addition of a low concentration of additives in an viscous fluid undergoing an acoustic pressure field may change significantly the nonlinear motion of collapsing bubbles. Keywords. additive suspension, oscillatory bubble, nonlinear motion.