New optimal filtering approaches for hands-free telecommunication terminals

The use of Wiener filtering to simultaneously reduce all the perturbations at the sound pick-up of hands-free terminals is investigated in this paper. This analysis of perturbation reduction is a global approach as all types of perturbations to desired signal are reduced by a unique filter. Filters derived from this approach are applied in two different contexts: hands-free radiotelephony in cars, where two distinct perturbations have to be considered, noise and acoustic echo; and the teleconference context where the global approach was performed on residual echo remaining after a classical echo cancellation. The use of psychoacoustic properties is also considered in order to improve the quality of the transmitted speech signals. (C) 1998 Elsevier Science B.V. All rights reserved.