Acoustic Echo Cancellation Method And Realization Technology

In recent years, speech signal processing technology and communication technology are developing faster and faster. There is also a greater demand for a better communication quality with the improvement of living standards. Hands-free voice communication system has been popular, such as video and telephone conference, hands-free telephone etc. Acoustic echo is the primary factor which influences the communication quality of this kind of hands-free speech, so solving acoustic echo problem in the hands-free voice communication system is a hot issue in the research and attention. A large number of people have done a lot of research on adaptive filtering algorithm, simulated by MATLAB, several achievements made. However, simulation experiments cannot completely simulate the real communication environment due to the complexity of the actual communication environment. So there is a great difference between the simulation results and actual results.This paper devotes to construct a hardware platform of acoustic echo cancellation based on DSP, with the research of adaptive filter and its relevant algorithm. Echo cancellation processing is conducted with actual speech signal and real conversation environment, making a further attempt for hardware implementation and application of adaptive filtering technology. The methods of theoretical analysis, software simulation and hardware design are used. The influence of related parameters on the performance of the adaptive algorithm is verified by software simulation, based on the study of adaptive algorithm. The performance of adaptive algorithm is compared by the results of echo cancellation experiment. Finally, hardware realization is completed, based on acoustic echo cancellation platform constructed by DSP.First of all, this paper researched the basic principle of echo cancellation algorithm through an analysis on the causes of acoustic echo. The process of derivation and the basic principle of LMS algorithm are researched. And the factors which affect the performance of LMS algorithm are analyzed. Secondly, several variable step algorithms are research and they are compared with standard LMS algorithms. Thirdly, this paper conducts the simulation to the standard LMS algorithm and variable step LMS algorithm and the difference between them are compared. Finally, echo cancellation platform in actual communication environment is constructed, based on the DSP of TMS320F28335, which is produced by Texas Instruments. Then the test is conducted in actual voice and simulation result is compared with actual result. In the meanwhile, this paper studies double talk detection technology and realizes it, due to the existence of single talk and double talk in practical communication system. In addition, the echo cancellation in stereo environment is discussed in this paper. The research status and development tendency are also analyzed.