A SYSTEM FOR SPEECH ENHANCEMENT IN THE CONTEXT OF HANDS-FREE RADIOTELEPHONY WITH COMBINED NOISE-REDUCTION AND ACOUSTIC ECHO CANCELLATION

This paper addresses typical problems encountered with hands-free equi pment in the context of GSM radiotelephony. We first summarise some im portant characteristics of the noise field in moving vehicles, and we also describe the acoustical echo phenomenon. We show that, in order t o provide sufficiently high speech quality, these hands-free equipment s should include noise reduction (NR) and acoustic echo control (AEC) devices. We then describe two possible structures combining noise redu ction and acoustic echo control. As a conclusion, we raise the fact th at the choice of a particular structure, among those proposed, is cond itioned by the performance of the adaptation algorithm of the AEC solu tion.