Adaptive Echo Cancelation for Voice Signals

Abstract

This chapter deals with modern methods of dealing with echoes that may arise during a telephone conversation. Echoes may be generated due to impedance mismatch at various points in a telephone connection, or they may be generated acoustically due to coupling between microphones and loudspeakers placed in the same room or enclosure. If unchecked, such echoes can seriously disrupt a conversation. The device most successful in dealing with such echoes is the adaptive echo canceler. Several million such devices are deployed in the telephone networks around the world. This chapter discusses the principles on which echo cancelers are based, and describes their applications to network telephony and to single- and multichannel teleconferencing.