A system for speech enhancement in the context of hands-free radiotelephony with combined noise reduction and acoustic echo cancellation

Abstract

This paper addresses typical problems encountered with hands-free equipment in the context of GSM radiotelephony. We first summarise some important characteristics of the noise field in moving vehicles, and we also describe the acoustical echo phenomenon. We show that, in order to provide sufficiently high speech quality, these hands-free equipments should include noise reduction (NR) and acoustic echo control (AEC) devices. We then describe two possible structures combining noise reduction and acoustic echo control. As a conclusion, we raise the fact that the choice of a particular structure, among those proposed, is conditioned by the performance of the adaptation algorithm of the AEC solution.