Elimination of echoes from voice communication

From the subscribes perspective, echo is arguably the worst type of impairment that can be encountered during a telephone conversation. The echo canceller´s goal is to detect and remove echo as quickly and effectively, thereby minimizing any loss in voice quality. The echo canceller must perform this function under all conditions including double-talk (when both parties are speaking at the same time) and in the presence of background noise. Furthermore, the echo canceller must not cause detriment to signalling tones or fax and modem transmissions. In order to combat the echo phenomenon, an echo canceller is employed. Today´s echo cancellers use sophisticated algorithms running on high speed Digital Signal Processors (DSPs) to combat the echo. The focus of this study is to develop an echo canceller by using Least Mean Square (LMS) adaptive filter. Simulink is used as the simulation tools, where the echo canceller can create a model of the echo path by sampling the voice signal that can estimates the echoes. This estimation subtracted from the incoming voice signal allowing normal speech to pass through. This is a very simplistic view, as echo cancellers need to have the capability to sample multiple echoes occurring at different times and at different levels.