Adaptive Filtering Algorithm for Acoustic Echo Cancellation in Hands Free Communication System

Abstract: Acoustic Echo Cancellation (AEC) is a common occurrence in today’s telecommunication systems. It occurs when an audio source and sink operate in full duplex mode. In this situation the received signal is output through the telephone loudspeaker (audio source), this audio signal then gets echoed through the physical environment and picked up by the systems microphone (audio sink). The effect is the return to the distant user of time delayed and attenuated images of their original speech signal. The signal interference caused by acoustic echo is distracting to both users and causes a reduction in the quality of the communication. Here the focus is on the use of echo cancellation algorithm by making use of adaptive filtering techniques to reduce this unwanted echo, thus increasing communication quality. Adaptive Filters are a class of filters that iteratively alter their parameters in order to minimize a function of the difference between a desired target output and their output. In the case of acoustic echo in telecommunications, the optimal output is an echoed signal that accurately emulates the unwanted echo signal. This is then used to negate the echo in the return signal. The better the adaptive filter emulates this echo, the more successful the cancellation will be. Performance parameter of pro-posed algorithm will be analyzed using Echo Return Loss Enhancement (ERLE), Mean square Error (MSE), and Convergence Time.

Keywords: Acoustic echo cancellation (AEC), Echo Return Loss Enhancement (ERLE), Mean square Error (MSE), Convergence Time.