The Full-band and Sub-band Systems, Adaptive Combination of Sub Band Adaptive Filters

1 Al-Falah School Of Engg. &Tech., Hayarana, India 2 Al-Falah School Of Engg. &Tech., Hayarana, India 3 ECE, SDEC, MTU,Noida,(India) Abstract: Communication technology has advanced to the point where teleconferences that use communication lines to connect remote conference rooms are taking place every day. The use of a centralized acoustic echo canceller in the mobile switching center of a GSM network allows the operator to enhance the audio quality before transmission to all subscribers. However, the main problem is the impact of the speech coder/decoder nonlinearities along the echo path. In this paper, we propose a combined acoustic echo canceller/post-filter based on perceptual properties to reduce the coding noise. Theoretical and experimental comparisons against classical solutions are given to evaluate the performance of the proposed approach in a centralized context of echo cancellation. Echo is the time delayed version of the original signal. Acoustic echo results from a feedback path set up between the speaker and the microphone in a mobile phone, hands-free phone .Echo can degrade the quality of service in telecommunication. Therefore echo cancellation is an important part of communication systems. A new approach based on the number of coefficients in an adaptive finite impulse response filter based acoustic echo cancellation setup is an important parameter, affecting the overall performance of the echo cancellation. Too few coefficients give under modeling and too many cause slow convergence and an additional echo due to the mismatch of the extra coefficients This paper focuses on the use of adaptive filtering techniques to cancel this unwanted echo thus increasing communication quality