NEW OPTIMAL FILTERING APPROACHES FOR HANDS-FREE TELECOMMUNICATION TERMINALS

The use of Wiener filtering to simultaneously reduce all the perturbat ions at the sound pick-up of hands-free terminals is investigated in t his paper. This analysis of perturbation reduction is a global approac h as all types of perturbations to desired signal are reduced by a uni que filter. Filters derived from this approach are applied in two diff erent 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 resi dual echo remaining after a classical echo cancellation. The use of ps ychoacoustic properties is also considered in order to improve the qua lity of the transmitted speech signals. (C) 1998 Elsevier Science B.V. All rights reserved.